No spark gt125r 06
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Bike Model = : Gt125r 06 carb
No spark 2006 gt125r carby (bought the bike as a non runner cranks but no Spark, all electrics work)
Hi so before posting I’ve tested the battery, HT leads (coils), replaced the spark plugs and tested the cdi unit (resistance)I got a reading for the pickup coil and it is:
105.1ohms
And the reading for the stator is: 07.8ohms
I’m not sure if these are good readings or bad.I then decided to test the blue wire that goes from the pickup coil to the cdi unit end of the wire and got no continuity? (No beep or reading).
And with the green wire i got 117 on continuity mode.So I’m unsure if the wire is the fault or if the pickup coil or magneto is faulty
Bike been in shed for 3 months i need help plz 😭
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Sounds like a faulty stator unit, because if the CDI can’t sense it, it won’t send any sparks to the coils itself.
Did you also measure primary & secondary resistance of the ignition coils fella ?
Also if you can, remove the “HT CAP” thats on the coil itself. Then put your meter to 20,000 ohms.
Measure the HT cap on its own, tell us the resistance. The black caps are common to fail the sparks due to heat damage after a long while in the bike, since down the plug hole gets very hot. Though I would normally suggest to just upgrade to the heat resistant rubber NGK caps (NOT PLASTIC ones , they will crack!) , but if the black caps are OK , then go on amazon and look for “MAGNECOR HT WIRE” , these HT wires are great for maintain a consistant connection between the CAP and the Ignition Coil itself.
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I must stress, before fitting a new stator , get a BEEFY regulator. Like the one you see on the store above ^
NO aliexpress , No Korea OEM regulators = these things are usually so bad its the #2 cause of all electric problems on the bike and plus some of them allow the battery to charge to 16v and fry the loom. Not worth the risk.
Just a shout!
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Hi, i did check both primary and secondary resistance of the coils.
The cap readings are (multimeter set to 20k)
Coil 1: 8.73ohm
Coil 2: 10.40ohmRegarding that blue wire that goes from cdi unit to pickup coil. I’m not sure if it is faulty as i was not getting continuity when i hooked the multimeter to the pickup coil end of wire and to the cdi end of wire.
Oh and will purchase that regulator once I order the other parts, so do i go ahead and order the stator and pickup or should I do more testing?.
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Stator + Regulator together = on your basket , definitely will NOT trust using any old regulator on a new part as these 2 parts are married like chain & sprockets.
Caps = They seem OK? If they don’t spark, get NGK ones but if budget is a concern, then we have these ones that work.
We have 2 of them left:
https://www.ebay.co.uk/itm/256805062129Make sure you have dust caps!!!!
https://www.ebay.co.uk/itm/254136676637Spark Plugs = Go to halfords and get “Yellow CR8E” only , do not touch the “IX Blue Iridiums, they are “!#@” is all we can say.
When she runs , upgrade to the “LASER” ones you see on this bike forum.CDI unit = It should be OK, but it’s the last thing we need to replace right now. Just make sure the main bike harness has every connector / plug cleaned up with shiny pins. Use contact cleaner and dry over night. Then ONLY use “ACF50” (spray a tear drop / rain drop of that in every single plug on the bike) .
Good job on checking the actual ignition coils. What are their readings without the HT cap attached to them?
Regards
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Hello again
Soo Ive got some NGK CR8E sparks i bought from Halfords earlierThe readings for the coils without the caps are:
Coil 1: 5.70ohm
Coil 2: 5.72ohmGonna order stator unit and regulator now, stator unit should take about 15 days or more to arrive, are there any more tests i should conduct whilst i wait for the parts?
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1 more test , “Coil TERMINAL pin + Coil Bolt Hole” ==> What is the resistance (less than 5 (five) ohms please) Then i will tell you if the coil is good.
If you order the stators from us, it may come sooner than 15 days but possibly! – I usually try to be as rapid as I can.
In that time, strip her and clean up the harness and get “harness tape” , wrap it twice to insulate it more , but i hope this keeps as much water and mud away from rotting the wires.
Believe me , I washed my bike yesterday and I was stupid to allow water inside the seat , the fuse box got a little wet, i dried it off and i lost 1 volt! = 1 volt!!!
So instead of 12v, i was at 11v, the starter motor would not crank. So i replaced the fuse again and re-cleaned the terminals , it started up good! – It is amazing that water or bad contacts can cause an easy voltage drop (higher resistance , so heat risk there too!) Any harness made after 2012 is SENSETIVE!
I had an 2008 GT carby for a while, it’s harness was 2x thick and said “GT250R” as the factory harness used on both carby 125 & 250 until 2008
If your 125R is 2016 , you would be extra careful with the harness as they are much thinner.
Since you have a 2006 bike, i hope your harness says “GT250R” in a white sticker near the battery area and you have a thicker one (i’d be jealous as they are very hard to get now and last for ages!) All 650GT after 2008 are EFi now, so oh well , fuel injection it is and extra zillion sensors to pay attention to!
Stay carby!
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Im back
Soo about the ignition coil test, do you want me to test primary coil (power pin and bolt hole)? If so the reading is 0.2ish, the termials do need a clean tho as they are a bit rusty.As for the harness it does not exist 😭
The bikes wires are all taped up by previous owner, not sure if thats a good thing or a bad thing as they are taped up good so i doubt water will get in em. I believe the bike was left outside for some time in winter by previous owner and there are signs of rust in some places and some connectors are a bit rusty, the fuel tank sensor has rusted out completely no reading from it (bike shows full fuel on gauge). This bike is a 06 with high mileage, i dont know the exact mileage as it has been tampered with in the past, at one point it had 30k then straight to 0 then to 20k now at 23k on the odo, so it has been used alot and by age probably falling apart but should be fine, hopefully.There was a video uploaded to YouTube, someone selling my exact bike 13 years ago, which i found interesting as apparently it used to have a alarm system installed.
Still has the fuel tank dent
And fairings are in ruff shape without paint.
Still waiting for the stator unit should arrive by the end of the month. -
Im back again, so I’ve installed the stator unit hooked up the wires yet still no spark.
But as I was moving stuff around a wire from cdi unit just flicked out as if it was in there but not connected, I believe it leads to killswitch but not sure, it one of the wires of the dual connector on the cdi unit I’ll upload a pic here
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This topic should help verify the CDI has the correct wires going in to it.
Needing a little help with my current project (+GT125 CDI PIN OUT)
Regards
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Hi so I had a look and yes the wire does go in the place I presumed it would, but I’m not sure what it’s for, on wiring diagram it goes to “Engine Stop” and to a photo I seen on the forum apparently “12v ignition” it’s the orange and black wire that goes into the 2 wire connector in the middle of cdi, the wire next to it is black and yellow wire, I was wondering what this wire does and how can I test it before I put it back together as it looks abit burned. Thx
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Oh I see, so this could be the issue, I tried pushing it back in the connector while cranking yet nothing. Any way to test it before i fix it up?, as I have a feeling it may be damaged.
Follow the orange way all the way to the front of the harness and test with a meter for a breaks , as a possible short somewhere that’s stopping the electric flow reaching the CDI
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So ive followed the orange and black wire that was broken and it connects to right handle switches. I tested the wire to the nearest connector and got a reading/continuity. I then repaired it (new 2.8m spade connector). Now after installing cable, still no spark. All the switches on the rh seems to work, killswitch stops the starter, starter button cranks the engine, and headlights work. Im not sure on what to do now?. Do the switches need further testing?.
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So ive followed the orange and black wire that was broken and it connects to right handle switches. I tested the wire to the nearest connector and got a reading/continuity. I then repaired it (new 2.8m spade connector). Now after installing cable, still no spark. All the switches on the rh seems to work, killswitch stops the starter, starter button cranks the engine, and headlights work. Im not sure on what to do now?. Do the switches need further testing?.
Coils (are they new?) ==> Check the Plug cap wire is not broken (stops the signals going to the plug)
Stator Unit (wrong one ordered?) (yes it does happen!)
Side Stand Switch = If bypassed, check again. Trust me, even crud under the tape will turn the CDI off from sparking the coils.
Clutch Switch = would NOT recommend bypassing it as “fake neutrals” can happen and bike falls down as soon as you press start , ask how i know!
If the switch is gone, its a quick cheap replacement.Now right there above ^ are what would stop your sparks.
Get a friend to push you down the street ==> Drop to 1st gear , if the bike won’t start from a push & bump, then its defo the above ^
Harness = I will assume you’re going over it like a fine tooth comb where no single wire going to CDI has a breakage. Even the wires for the coils (see link i gave above for CDI layout)
Worst enemy is CDI replacement.
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IT FINALLY SPARKS!!
I decided to have a look at the black and white wire connecting to cdi labelled ground and it was pretty rusty and bad connection when hooked with multimeter to fuel gauge, after cutting and replacing the connector, THE BIKE NOW SPARKS, thank you for helping me fix this issue with my hyo (might not be the only issue as i bought this bike as no spark, so havent tested beyond that)
Regarding the uprated regulator i bought of hyoriders shop, i cant get it to fit even when moving the wiring out of the way, prob just gonna use the old one as the new is massive.
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Make sure the plugs face the back tyre.
So that rain from above ^ or rain water from front tyre < ==> isnt trying to rust up your plugs.
The shop did say the regs will be a monstrosity and said “get creative” fitting.
Go back to the shop and look at the customer galleries for correct fitment , grounding to frame isn’t needed , don’t cut anything! – super strong zip ties help too.
Hyosung in 2020 onwards put their update regs UNDER REAR TYRE! (good for cooling but man , they get wet fast!)
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If the bike kills a massive reg within the 1st ride, we have a problem! = Check all electrics and test your stator (can’t stress it) , if the stator is wanning, your massive reg will pop.
The “teeny” grey one was discontinued & re-called by hyosung as it was causing fires.
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Hi a update on the 06 gt125r
After getting spark i gave her some fuel and cranked, only ran when full choke and full throttle and like 10s of cranking, once idle for a bit then would rev up perfectly but would cut out after some revs when trying to idle again. Decided to clean up carb, once carb was clean reinstalled and tried cranking wouldnt start up… the fuel mixture screw was tampered with before so i decided to give it 2.5 out and cranked it, the bike started first try without use of throttle and was idle good, but when id try give it revs it wouldnt budge unless i held the throttle open for about 5s then it would rev up and rev up perfectly and then idle, but after 2m it would cut out and not start again it would try but wouldnt be able to, i checked the battery and charged, now after multiple attempts apparently this bike will only start at 13.2v and it always cuts out at 13.07v like always at that number, at first i was thinking it may be the carb but after searching online apparently the battery could also cause issues like bike not reving up (mine does rev up but needs throttle on for a couple secs). As the bike only starts at 13.2v and not at 13.07v guessing the battery is at fault and needs replacing?, will buy YUASA YTX 14BS battery as a replacement.
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Keep us posted.
Your old battery may not be holding its juice very well (weak cells inside despite whatever voltage it says) , a fresh YUASA is advised yes (make sure it’s a genuine one from Halfords or TanyaBattery on ebay , other sellers selll either fakes or very old stock!) Time stood is the battery’s enemy, so the fresher the better.
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Just had the new battery installed, and now she can crank for longer before battery dying, but… now she wont start up first time, i got her started by spraying some ez start in intake. She ran and kept running but anything under 3k revs she dies, does rev up good, responsive revs, after running for a while i turn the engine off and after that engine wont start, i tried spraying more ez start but that wouldnt work, after waiting for like 10-15m i then spray some ez start again and try and she starts and same thing under 3k she dies, i tried cranking with throttle quarter open half and full yet nothing choke down nothing, engine does sound like it wants to start but cant catch on fully, last time the engine was able to idle and after holding throttle for 5s delay it would rev then die when trying to go back to idle, but when originally cranked would idle at 2k, now the thing thats linked to idle would be pilot jet and if blocked it would die at idle right?, but bike should still start if i opened throttle? And the fact that the bike will only start with ez start after leaving it for a while. (Btw did clean carb Before).
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Not just the pilot jets clogged, but remember the “Permanent Jet” that is next to it? That is for starting and nursing her to idle back to Pilots. Those 2 cannot be blocked and including the passages inside the carb itself.
If the Pilots are clear, but also use Compressed Air with a straw, spray every little hole you see inside the carb until you can hear swooshing inside (pathway now clear)
Remove the intake manifolds -> Replace the o-rings (These little bastards) make the bikes hard to idle if they even so much as let some vacuum escape under there
If the o-rings are new -> Try to fully clean the surface where they sit so it’s 100% smoothed out. use a PLASTIC toothbrush and scrub hard (no wire brush!)
Then use a little bit of Engine Oil to dress up the o rings wet and install them back.
When it runs , spray carb cleaner around that area to see if revs rise again, then you may have some kind of crack on the intake pipe itself.
AirBox = Front Carb on front Cylinder ==> Check the airbox has fully consumed the front carb, if you see silver lip (carb top rim?) sticking out, there is your future idle problem there.
Final checks, make sure when its hot, do a compression test. I believe it really needs compression checking now.
Let her warm up 10 mins.
Both Spark Plugs out
Full Throttle
Crank It for 5 seconds
Get readings for each cylinder and let us know.I went all over the place in my reply but i hope i made sense.
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Sprayed carb cleaner on intake pipes and had a look around and nothing, vacuum seems fine over there, Opened the carb up, sprayed air into every hole, removed jets sprayed air in there, everything seems clear, closed carb up and tried starting her, wouldnt start sprayed ez start in intake and she started and kept running, randomly started reving up high to about 7k then to 9k then back down and then again, i let the bike do its thing for a bit as long as it leeps goong back down and not hanging at a high rpm eventually it started going back to 2k but then would rev back up to 3-4k by itself, after waiting for a bit it shut off, wouldnt start unless i used ez start and after getting the engine running again it would only idle at 3k rpm and would die at any under just like before, still waiting on the compression tester to arrive. As the bike was randomly reving up it drank decent amount of fuel the fuel filter usually full of fuel as i look at it, now only quarter full even when bike running.
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Im back with some mixed info on the bike
Soo compression tester arrived today soo got the bike started with ez start but died within 2m i checked the fuel filter and all fuel was drained from it. So at this point it looks like a fuel issue cuz no matter how much i crank fuel filter is same, so i decided to take of the suction pipe on put my finger on it, it was sucking air or something, a bit on the low side but i wouldnt know how strong the suction is suppose to be, i then took off the tank, and hardly any fuel was dripping from it. I then blowed into filter and could hear clear passageway as in i could hear air go around past filter, i then sprayed ez start in intake again and now starts up like everytime without tank with ez start, now gonna get new fuel lines (seen some on hyoridershop), already have a spare fuel filter. Now how do i go with cleaning the tank properly and clear any blockage?. Also one of my spark plugs the rear one center of it is white, front is tiny bit white. Now the other part, i wasnt able to keep engine running for 10m but ran for about 2 or less at 3k rpm engine was warm but not hot, i then removed both spark plugs, tank is off aswell and cranked on rear i got 75psi and front 65psi throttle on full, now the tester i got is a cheap one from ebay and the thread isnt long as in the thread length is only a quarter long so sits higher then a spark plug. So i don’t know if the reading is correct and the last thing i want is less compression, as the cost would be a lot and i dont think it would be worth it as i bought this bike with my fist paycheck at this job i got around the time so i could use it as a fun commuter bike, it has 23kmiles which is not that bad but it is what it is, is there any other way of testing this? Or confirming, as remember the bike did run at idle and would start up first time not long ago and would rev up nicely if i held the throttle for a couple of secs, and even now with ez start it starts up fine. Compression issue is what i feared after buying this bike really hoping it aint.. -
Did you test the compression again one more time please and use the “METAL Pole” like this:
Use the Straight one with the curvy rubber tip, and press down hard on the spark plug hole.
Tell us the compression (even cold, although “hot” would be prefered as per OEM ) with full throttle and both plugs out.
Do this with a fully charged battery
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I think its time to rebuild the front cylinder
At minimum, you want around 125 PSI
Hyosung says the limit is 110 psi hot and healthy range is 140 – 175 psi
Here is a cheap front barrel and piston, it should be OK
https://www.ebay.co.uk/itm/256864818680And here is a spare one
https://www.ebay.co.uk/itm/255751060887I have confidence that either of the above will finally get the bike running.
Ofcourse make sure to get new gaskets you see on this shop
Rear is already at the limit of 110 psi but… If you have to do the rear, then check these out
https://www.ebay.co.uk/itm/256513929819Hyosung Korea isn’t making new pistons for carb 125cc or rings.
I am slowly researching and soon will test custom piston rings off another bike that may fit our bikes. If you just want piston rings, then i think you should email me , but stock is rare now.
This is why you can’t idle, the compression is too low.
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Hmm interesting, the engine was cold when these test were conducted as fuel tank is blocked, is there a way of finding what the exact issue is? And could it be something as simple as valve clearances?, now for this bike i did buy it knowing the risks as it is high mileage and still want to get it running. Now regarding piston rings, couldn’t find any specific for my hyo and would probably be expensive, how would I go around my engine diagnosing this compression issue?, 1 way is to strip it completely, but would take some time.
On the side I will also have to clean the tank ask it did have rust before, not really sure what to use to clean it?
New hoses, already new filter but might aswell switch it out. -
There is a few youtube videos on guys with very old suzukis as they still had metal tanks, some use vinegar, some use white spirit combinations and there was a product used to clean car tanks (metal tanks of old 20th century cars) but keep forgetting the name of it, some also use metal marbles and shaking the tank all day , then using magnet sticks to scoop out floating rust after the fluids have drained out. There is many ways to do it , just make sure the tank is fully dried out but if liquids touch the paint, be ready to cry and likely go to the bodyshop to get it resprayed properly.
Compression Loss as per manual, so i will quote it from the horse’s mouth:
Low compression pressure can indicate any of the fol
lowing conditions :
●Excessively worn cylinder wall
●Worn-down piston or piston rings
●Piston rings stuck in grooves
●Poor seating of valves
●Ruptured or otherwise defective cylinder head gasket -
Got new fuel lines and fuel filter, and cleaned tank using vinegar,installed everything, and tried cranking the bike, it cranked but no fuel in fuel filter even after cranking for a while,
Would low compression of, 110 and 90 cause fuel to not flow, or is it something else? Starts on ez start, then dies and still no fuel in fuel filter -
Got new fuel lines and fuel filter, and cleaned tank using vinegar,installed everything, and tried cranking the bike, it cranked but no fuel in fuel filter even after cranking for a while, Would low compression of, 110 and 90 cause fuel to not flow, or is it something else? Starts on ez start, then dies and still no fuel in fuel filter
Sounds stupid, but please excercise caution! –> Grab 2 vacuum hoses going to the tap and pump, get someone else to press start & hold clutch in for 3 seconds.
You should feel the pipes trying to such your cheeks , then vacuum is there but if its weak or non-existent, you have a leak around the carb or intake pipes.
Also, keep in mind it is possible the pump or tap my be clogged with debris preventing the fuel coming out ? And make sure the “WHITE PART” of the fuel filter is facing the pump (If the filter was in reverse, it would cause problems), the filter has a direction arrow that shows the fuel flow direction. Your fuel pump will have arrows too on the gold ports for fuel flow.
Silver port on the fuel pump is vacuum from the intake manifolds.
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Soo took the vacuum pipe off, felt both holes on each intake pipe and feels like they are sucking the same, 1 of them (front cyl) was really dirty but still had suction, reconnected pipes securely and it has suction when feeling it, but not sure how strong the vaccum pipe is supposed be, now the pipe going to tap had suction but really low suction, could hardly feel, was able to get bike started with full choke, only dribbles of fuel in fuel filter. Somehow was able to idle, when given revs it died and fuel filter was fully drained, started it again and was able to give revs after a bit of trying but once again only dribbles of fuel in fuel filter. Now the tap i pulled out the day before and gave it a clean and when removing tank today it did drip a couple drops, the suction part on pump could be blocked, but the fuel line part on pump i used compressed air on before and it passed air through.
Fuel filter is on right way, and pump pipes are on correctly, the large pipes wouldnt really effect the suction right?. Originally the bike didnt have this problem, the bike started fine at one point and would rev if throttle was held open for a while, then after leaving the bike for almost a week waiting for new battery then this issue started to happen 🤔. Bike had no more fuel in filter, so i replaced pipes and filter yet nada. So as im aware there are 2 suction pipes, 1 that connects to tank (i belive helps fuel flow through tap) and the other one that should pretty much power the pump sucking the fuel directly in through the fuel pipe?.
(Also other suction pipe sucks air 👍.)
Rn have about 2l of petrol in tank which i think is fine right?. -
larger pipes are only an extra 2-3mm in diameter, it doesn’t bother it, its thicker as double braided inside, Hyosung says discard all its grey stock lines after 4yrs new , so we might aswell beef them up with pipes that are good for 10yrs and handle heat better, so less chance of your fuel misting towards the carb. Helps a tad.
Large filters are intentional and the size is like your 1-2 mile emergency reserve to quickly find a petrol station but if the tank starts flashing, the bike warns you anyway that you’re low.2L of fuel should be OK in side the tank (i expect that to be 2-3 bars in the dash)
If the bike runs on choke, what happens when you rev very slowly ? and what sounds does it make ? this could be key.
I am suspecting (again) clogged pilot jets and the permanent “jet” that is next to it which controls starting up & “idle switch to pilots”
This video is 100% accurate to our carbs (except we are down-draft upside down type) but the animation is the same (for the most part)
So you can see which areas of the carb affect different throttle positions and idling and starting (with or without choke)
(It wont play on here lol, but click the link inside the youtube box below to view it in an App)
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Starts on full choke about 2k rpm then goes up to 4k, once at 4 k if given revs it will splutter then sometimes rare occasions catch back on (most of the times it dies when try to rev) and continue to rev, it does not die on full choke but when choke is removed it dies but if I let it go to 2k I will then have to use full throttle or choke to keep the bike alive until it revs back up
Won’t start without full choke
Sound it makes is hmrhmrmhm drdrdr (sputter death sound) even if small touch on throttle.Fuel sensor is broken but not worried about that right now
Still hardly any fuel in filter
Soo the jets I’ve cleaned them 2 times previously with carb cleaner and compressed air, air passes through all of them fine, what’s the next step if it the jets? Replacing them? Or could it be the passage way in carb that I also tried to clean.
Thanks for the video was very informative
And i see now why it may be the jets, as choke has a different way of sending fuel into the engine
, but still not sure 😕 -
At this point , I would try to get jets (pilots and mains) and make sure both carbs use SIZE 15 mains.
Then Rear 92.5 and front 90 for the mains
Mixture screws, start at a 3 full turns out each and leave it there as that’s close enough to OEM settings
If it runs worse, then do 2,5 full turns out each max.
Air blast the carbs again for one last time.I would also be suspicious of the intake pipes for their o-rings or even the airbox being missing? or intake rubbers cracking?
If the air is good. Look at the filter again, when it runs on check, the tap should let out a small steady stream of fuel ?
Normally after idling around 2k for a few minutes hot, the filter should be half full. General riding will be “50% to 80% full, as it is a big filter enough to fill both carb bowls if it has to)
If not, did we replace the “Tap” and “pump” ? if you suspect it being starved of fuel to idle properly
Twisting a throttle up, should squirt more fuel through the mains as the slides lift (like you saw in the video)
Keep that video in mind when doing rev/throttle tests on the carb.
Choke is more like a “by-pass” thing to quickly wake up the bike before letting it idle on its own pilot jets.
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Ok so the mixture screw is already set at 3 turns out as when the bike ran before this issue it was perfect mixture, ill pull the carb out and the intake pipes and give em a clean again and send pics, airbox is intact, when the bike runs the tap does release fuel in a small stream, but when tank is disconnected it drips. (when full choke it streams fuel). Now thinking about it if air is restricted (as in not enough air in engine) it would cut out similar to how it did, would the bike run without the air box?, bike is in shed rn, but i heard that dosnt really effect the bike running, the carb slides could effect air intake, its either got less air or less fuel, one of the 2, my rear spark plug the center is white and this was the time when the engine starved fuel.. ill check the front one to see is thats changed.
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Having the airbox fitted makes it easier to run in fairness, hence these carbs never ran right when people started putting pod filters on them.
If the bike is air staved, the plugs would be very sooty or wet-like texture to it but it can also mean weaker ignition parts (weak sparking system) in tandem
Shed/Garage doesn’t affect anything unless its really windy outside you gotta work inside! but keep the doors open though, as you don’t want to be choking on that gas out of the exhaust.
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Soo removed carb and used compressed air in every hole of carb and in jets, when carb was removed it was dripping fuel but not from the hose part ill send a pic and circle it, now the intake pipes while taking one of then off unfortunately i was unlucky and a bolt snapped was able to remove the intake pipes both of them and will send a picture of their condition, now regarding that bolt that snapped the head snapped and luckily there is a good chunk of the bolt still sticking out, soo i tried to remove with vice grips but too tight, any suggestions before i use mr dremel and put a line in center of bolt so i can remove with flat head?, cuz really mr dremel is always my last resort, back to the carb everything seemed clear the thread of the jets did have some white powdery stuff on it (wasnt on there last time) air passes through jets perfectly, could get some air in the main jet hole (the actual carb hole on carb not individual jet)but obv it has holes in it soo cant get that much air pass. Also checked front spark plug and it was basically same as i left it.
Should be 8 images below
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Was the “Add Media” button not working on the forum ?
Also, in regards to the bolt stuck there…
- Hairdryer ==> blow the intake hole on cold setting or compressed air. Even a small rock dust will grind your piston rings = compression loss or burning oil later.
- Then plug that hole before doing repairs
I suspect a dremel should do it or weld a nut on to it?
If not, drill through it , and use Heli-coil kit to rethread it.
Carb unit =
- That hole in yellow circle means you need a hose attached there and also in the MIDDLE of the carb —> join up with a T-piece —> 1 long hose to the road, this is overflow/breather pipe. If the bike fell on the side where the coils are and fuel will come out of there 100% , if the hose is missing and coils get faulty (arc-ing / sparks escape, its an instant fire!!!)
Glad you noticed that!
- Cylinder Heads = Find a way to remove as much crud as possible until its very smooth (even attach a polish ball to a drill to smooth out the surface) then get new o-rings , you can’t trust those ones anymore.
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Oh was just that I added 8 images to 1 post and wouldnt post cuz of that.
Ok so gonna clean all that crud away, got some o rings in basket
Also sorry forgot to ask, I couldn’t find and replacement bolts for the intake pipe for some reason, got any links for me? Would help alot
Also regarding the carb, do I need replacement jets?, the air flys throught them perfectly, might be the passageway of carb could hear air go through them but not sure tbh, and could my issue be related to the floats or anything else in carb?
As I plan on ordering everything, then on a day I’m off work getting started
Hope I get this bike running and insured before summer ends.
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Hope I get this bike running and insured before summer ends.
That’s the plan!
Jets = Hold them in the air , look towards the sky and see if the holes look clear to you then the jets are OK. Probably meant the carb needed extra air inside its passages.
Check float height while at it and make adjustments as this topic below has an image of it
Actually also, order new floats (saves you messing around) and get a new gasket kit (which has new float seats) , essentially the bottom end of the carb is now all new and you don’t have to go there again.
Just make sure no white stuff goes to the carb again , it should always be clear unless you can see bits of crud in the filter (then the filter is doing its job trapping the dirt) , since you have bigger pipes => by that logic , if the pump & tap are good, then fuel should be gushing down hard towards the carb quickly (but will take a few cranks with throttle shut to fill up that filter.
If the filter is full or 50% full, then assume the carb bowls are fully and floats have switched off the seats , the bike can get started.
Get a can of yellow Easy start (2 cans even)
Intake Bolts = Ill send you free. Just send an email or put it in the order notes “Include manifold bolts” , and i may even send a couple extra bolts for the carb if it needs it etc.. No charge.
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Soo removed carb and used compressed air in every hole of carb and in jets, when carb was removed it was dripping fuel but not from the hose part ill send a pic and circle it, now the intake pipes while taking one of then off unfortunately i was unlucky and a bolt snapped was able to remove the intake pipes both of them and will send a picture of their condition, now regarding that bolt that snapped the head snapped and luckily there is a good chunk of the bolt still sticking out, soo i tried to remove with vice grips but too tight, any suggestions before i use mr dremel and put a line in center of bolt so i can remove with flat head?, cuz really mr dremel is always my last resort, back to the carb everything seemed clear the thread of the jets did have some white powdery stuff on it (wasnt on there last time) air passes through jets perfectly, could get some air in the main jet hole (the actual carb hole on carb not individual jet)but obv it has holes in it soo cant get that much air pass. Also checked front spark plug and it was basically same as i left it.
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I cant seem to upload my images
But basically its over for me, the bolt hole broke as in the hole is no longer a hole it snapped, i drilled out the old bolt, but the old heli insert wouldnt budge even with drill, soo i hit it with a screwdriver and yeah…
Not fixable is it…
Ill try send the pics, but yeah bad luck i guess. -
Oh no, 😭
I could supply a spare motor? But have to email me directly as its not on ebay yet.And do you get any errors please uploading images? Anything?
I want to try fix any bugs today
Use imgur website temporarily and copy BB Codes next to each picture
The forum will translate BB codes to pictures here quick
Wish i could see the damage on yours. It has to be possible to save it.
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Was thinking of a new motor, seen some on FB marketplace for around £150 which i think is pretty good price, but not sure about compression on them or wear and tear 😭, so too risky, i could get a replacement cylinder head but depends on the price. If its worth it, as the only damage is on the bolt hole on the intake pipe section of cylinder head,
Could get a professional weld on the bolt hole but not sure if it would hold or if its even worth it, will have to get a quote first
Oh and with the website, so basically the images show up when I paste them into this text box, but when I click submit the page goes back to the top and when I scroll down nothing is below. Then if I try again, it says something along the lines of “duplicate text detected” even tho there’s nothing here. Other time similar thing happened when I uploaded too many images.
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Was thinking of a new motor, seen some on FB marketplace for around £150 which i think is pretty good price, but not sure about compression on them or wear and tear 😭, so too risky, i could get a replacement cylinder head but depends on the price. If its worth it, as the only damage is on the bolt hole on the intake pipe section of cylinder head,
Could get a professional weld on the bolt hole but not sure if it would hold or if its even worth it, will have to get a quote first
Oh and with the website, so basically the images show up when I paste them into this text box, but when I click submit the page goes back to the top and when I scroll down nothing is below. Then if I try again, it says something along the lines of “duplicate text detected” even tho there’s nothing here. Other time similar thing happened when I uploaded too many images.
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Sorry , had to approve them manual. I will fix the uploader soon so it doesn’t always need to flag my attention due to too many images (which is a good thing, we love pictures!)
Get a threaded stud welded in there or try “JB WELD METAL” if you want to try yourself , it is possible to rescue it that way too. Now that side of the inlet just needs a nut!
If not ask mobile welder to have a look , and it should still be cheaper than a full engine , i hope!
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Everything put back together i give crank, no start i then double check mixture screws then idle screw, fuel filter only 15% full when crank. I sprayed easy start yet almost turned on but then didn’t and drank the 15% from fuel filter, got it started only once, only way to keep bike alive was full throttle, and was at about 2k rpm, after like 10s she revved up and I could rev until i let it drop and it died (same issue i had before). (Also when running i had a look at filter and fuel drizzle in to it like small stream at bottom of filter) Even after new jets full carb clean new Everything on carb, new o rings yet still same problem after that start couldnt get it started, not even with choke or ez start, with ez start it sounds like it will start but doesn’t. What do i do now?, nothing seems to work… I still remember that time couple months ago I got it started and it started first time then a week later it just does what it does now… might give up on this bike
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have you had any chance at all to do a compression test once you finally get the engine revved up to 2k once hot
2k idle is not ideal but if it can stay at 1800 rpm hot all day, it has a fighting chance.
Go on amazon and get AUXILARY tank , fill fuel in that little cup ==?> connect it straight to the carb , this can help determine if the pump and tap were also being too slow to keep up ?
Do the compression test first but make sure to use the “metal rod” , not the flexi-hose as it can give false readings.
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oh , make sure both plugs are out of the engine and do it full throttle for a few seconds fully charged, then you get some compression readings.
Also throw a little bit (tiny bit) of oil in the cylinders , and do a 2nd compression test again. Does it go up when the oil is added? (piston rings vs scored cylinders)
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Ok so the bike starts with easy start (pretty constant sprays) and idled for a couple seconds at 2k ish. Then does what is always did tried to die, was able to keeps the bike running after a couple more tries and had it running around 3k-4k for under 30s with some revs (revs were responsive after 3k-4k mark). The rear cylinder was hot, not the hottest, but hot and front was warm not hot, I kept trying wasnt able to get it started on easy start after that would try but then fail to run off tank.
Battery was charged before but may have lost some charge trying to get the bike hot, so not at 100% these are 1st try tests
Compression readings
Front: 95
Rear: 115
With oil in cylinder
Front: 145
Rear: 175
Tried testing with oil in cylinder again
2nd try but battery was dying then
So not sure if oil in cylinder test was low battery. (Did give good cranks tho when testing)
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Compression test above
Ok soo hooked the auxiliary tank directly to carb. This time bike would always start with ez start (wouldnt start on own) but at least it would start with ez, bike sounded alot louder, and would rev, i was able to hold throttle at certain position (I haven’t been able to set idle yet but was trying) and by holding the throttle there bike stayed at 2k for like 2m and then started to rev higher by itself and then die. Obv required a couple start ups to get to that point. When feeling the suction pipe that connects to tank it had good suction. The fuel pipes ones from carb to pump and pump to tank had suction but wasn’t as strong as that (pretty big difference). I guess for now and further testing ill stick with the auxiliary tank as it did help get the engine started alot easier.
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Shit! , okay i hate to be the guy to tell you that you will definitely need to get some spare pistons on ebay and CYLINDERS (both piston jugs and valves head)
Take the 2 heads off , replace them , also use new gaskets! – Your compression is too low hence it just struggles to maintain idle. It should be 125 psi “minimum” to get going but not ideal , and around 140+ , you have a ride-able bike. If its 175 psi that’s like a new bike.
Damn, now we can see why its been fighting and coughing a lot. The front barely got warm , and it is the one with the weakest compression.
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From the horse’s mouth , it says 250 but same thing.
https://www.manualslib.com/manual/865104/Hyosung-Aquila-250.html?page=36#manual
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Mmh right okay, so ill have to replace cylinder head and the cylinder barrel, how about piston rings?, and i could do this all without removing the engine right?
Also what would be an estimated cost
if its even worth the time and money spent.
A quick look at prices
Cylinder barrel £30 ish each £60
Cylinder head £100 each £200
And these are some of the cheapest I could find and condition apparently ok, not sure if its algorithm giving me these price but if I could get an estimate or some links. That would help out alot
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If you’re looking at the parts on ebay , i would just get spare pistons too. Least you can use the piston (incase yours is damaged) or take its rings to see if improves your older one. Cylinder Jugs = Justincase yours may be scored up inside causing compression loss
Cylinder Heads (valve heads) is just incase you want use newer / less mileage heads.Or possibly look in to replacing the whole engine if the labour is too much from your garages or if you don’t feel like doing it yourself. Garages have their own rates so i can’t estimate labour rates , you have to shop around.
It would be wise to remove the engine off the frame to do it all properly as its very awkward to do it while its inside the frame but you can, just very awkward, so it might test your patience or higher chance of making mistakes (ie. screw fell inside the engine!)
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Ok, ill take the head off and have a look to see whats damaged, cylinder jugs Id most likely replace same with piston rings, if piston is damaged I will replace that.
I still couldn’t find replacement piston rings
The garages would charge a lot, id rather do this myself as its would be alot cheaper and insurance on this bike is kinda high so will need some money for insurance.
So for now only parts im looking to order beforehand are, piston rings
And if you have any links for good cylinder jugs
Replacing both heads, jugs and pistons due to cost of parts a replacement engine or even a different bike might be a better option unfortunately…
Will get this engine open tho and will have a look
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Piston rings = Working on it as i myself want to stock them , hyosung is not making anymore pistons for carby bikes, as they moved on to the GV125-S EFi now (totally different engine)
Cylinders = check ebay , if you don’t see damage on yours , then ignore that but usually ask the sellers on ebay if the jugs are OK , personally i stripped some jugs off several bikes on ebay and most are untested as the engines had other bottom end issues (bad crank bearings etc) but i could not see anything on the jugs that would cause issues later so i listed them as spares / repairs , you could buy the cheapest jugs , send them to a garage to get them re-honed , buffed up or do it yourself so its super smooth.
Pistons = Best bet is to get the used ones , they will have rings you can take from. or use the pistons.
Valve Heads = Get ones that are said to be OK on ebay, saves you having to replace bent valves on yours if its causing compression issues.
Tear down first and see what’s going on with yours , if you ever put it back together , new-gaskets are a must!
Replacement engine is a last resort , don’t give up on her, you just found out the true reason why it struggled to start , the ex-keepers need a slap for abusing it.
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Ok so a problem, 3 bolts are stuck they are the main frame engine bolts that holt the engine into the chassis, I got everything else out only those bolts wont budge, left wd40 on them overnight yet nothing not even with my impact driver (170nm) am I supposed to slightly jack up the engine then take them out (maybe engine sagging?) Or have they just been torqued up crazy, I dont have a jack at the moment. So I dont know why they wont come out, almost snapped my ratchet.
Also yeah previous owner needs a couple slaps, he prob knew it was low comp but sold as no spark, my past self mightve needed one for not checking compression (unless he had oil in cylinder before to trick me)
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Try to tap in a socket in to the bolt and nut on both sides , get the impact socket, and use a breaker bar instead ?
Those frame bolts will turn to cheese , so be ready to replace them, it sounds like it was rusted in ? (owner not expecting to remove the engine but rode through mud & salt so much that anything not stainless gets seized in terms of bolts. Copper grease advised when refitting critical stuff!
Attack them tactfully as they round off easily but i took out the worst ones with breaker bar + a black impact socket
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Was able to take out those bolts (kept going at it with a breaker bar then followed with impact) engines out. Now I took the cams, loosened the tensioner (ziptie on chain so it dont fall) removed every bolt i can see on the front cylinder, even the main 4 cylinder head bolts (long ones), and there were 2 hidden nuts near bottom on the outside, I removed them aswell yet head wont come out, the one side without those 2 nuts is coming put but the side with the nuts I removed. That side is stuck on, tried a bit of hammering and prying still no luck, even tried lightly hammering the exposed screw bit that had nut on yet nothing, how to I get it off?
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K here are the pictures
Also took pictures of the other side of head and the screws and the top
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Hmmm, if the bottom 2 nuts are removed at the side of the fins , then carefully pull the whole thing upwards , otherwise i can only assume a piston is somewhat jammed there.
Get a butter knife , and carefully bit by bit => lift the sides of the cylinder gasket incase you’re fighting a gasket that’s really sticking the cylinder down.
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Used a wrench slowly to try lift it up once again the left side would lift but the right side i was able to make it wobble a bit (tiny bit) the gasket seems to wobble when I give it a little pry with flat head, but I can’t seem to get the right side off (the side that had the 2 nuts) could the 2 long screws be culprit the ones i took the nuts off? They are very rusty, did spray wd40 on it a day ago. I tried a bit of hammering, some soft prying with wrench, was even able to lift the engine up by just holding the head, thats how strong its on there. Yet that side wont come loose. No idea what to do gasket seems free and am able to move piston (obv after I push the head back in place as slightly lifted from left). Rn its at the top
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Remove the 4x long bolts if not done already , you can’t get any rust in there UNLESS engine was consuming water somehow ? or recovered the bike from a flood damage or something , if it was really badly rust, the 4x long bolts would have snapped trying to undo them inside the engine.
So try a strong piece of a flat head, and pry it upward.
We could possibly have 2 Collar Spacers under the cylinder heads being stuck to the barrel and the crank casing , they look like this:
(Example image from a similar vtwin bike)
They go through the long bolts actually.
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My bad, wasn’t talking about the 4x bolts, they did have a decent amount of corrosion on them, but was able to remove them, im talking about the 2 screw like bolts that hold cylinder head down on the outside (the ones I removed those small 10mm nuts from)
The screw goes from head to cylinder on the outside of engine, as thats the side that is stuck yet even hammering wont get it out, I tried a bit of prying again but that seem to damage the block it kinda just crumbles…
At the Worst timing my friend is tryna sell his yzf 125 to me for 1.4k which is not bad.. and it only has 3k miles.
If that ends up happening and i can’t get the hyo back running, then either parts or scrap which I never wanted to happen.
As even if i get the hyosung running with how old the bike is, i reckon more issues would show up
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Those would be just regular threaded little studs that go in to the cylinder heads (at the sides) , then 2/3 nuts just secures then down . You could slice (dremel+cutting disc) them off but be ready to buy new short threaded m6 studs , they are same as the oil filter cover if you get what i mean.
Either way , slide around the cylinders where gaskets are and pry upwards bit by bit , i am assuming the front tyre really chucked a lot of mud & salt at it, and you have a classic case “weather seizure” followed by heat of the engine , causing them to warp and get stuck in there. Go easy though as the studs are steel but cylinders are aluminium-cast metal mix !
Don’t give up yet if you got this far , if it runs in the end you will have more of a sentimental feeling over her than the new bike (possibly!)
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Was able to get the head off, there was a hidden nut, (had to remove the 2 hex bolts on the side cover) and a 10mm nuts was there, some hammering and the heads off,
I got some pictures could you let me know if there’s anything visually wrong with the top of piston and valves pls? Gasket I think deffo needs replacing. (Just click the arrows to go to the next photo, should be 5)
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1 brown valve in he picture looks like it has been through some hell judging by the edges of it.
A valve head change or valves alone + seals could be a safe call to change up. The valves are very hard to press down with your fingers , so amazon a cheap tool that allows you to compress or extract valves so you can see the full state of them and the seals (compression loss? or tiny bit of oil burning possible)
Pistons & The Cylinders, you would end up needing to remove the pistons and the cylinder walls now to judge their condition with your eyes
, if they all look good, grab a spare piston and use its rings to see if compression improves.
Remove the piston slowly! = So you can see which position each ring was, they have a notch on them and mark them. So next time you fit a piston, you can remember how they were.
Like this one:
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Removed the barrel, barrel seems good just some normal wear and tear, piston is good. piston ring end gap is 0.40ish (id say more around 0.45ish) but feeler gauge doesn’t have 0.45. Still can’t seem to find spare pistons or rings unless I spend a crazy amount on piston and barrel. I’ve only tested the top ring that should be fine right?
And when piston in barrel it doesn’t wobble or anything, just the normal up and down movement.
Now thinking about it, ik I found the issue and the bike may give sentimental value, but im not sure its worth it, the bike is pretty worn out and if i do get it fixed, im not sure about the reliability down the line, I think it may be time, to part the bike. Sell the parts and helpin other riders keep their GT125Rs running especially since parts for these bikes can be hard to find. Previous owners, had a decent amount of them didn’t looks after this bike, i believe at one point it had a crash, as fairings aren’t painted and clocks been switched. Also not original ignition barrel…
Might be the best option for this bike.
Very high mileage i predict 40-50k rn at 23k but mileage been tampered with or something like that.
Kinda lost the confidence in this bike.
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take some time to think about it , hunt down a spare engine for a quicker swap ? , you will still get more and quicker for a complete running bike. Plus you gt to learn a lot, so it’s not all waste as your next bike will be an easier fix as you learned what to do and what to look so next seller doesn’t try to sell you a lemon again.
Keep it as a slow rebuild , by Spring time , you will have a totally mint bike that can fetch £1.5+ K sold, running, fresh MOT. Parts will go but you will have half a bike that’s sitting there as your hardest things to shift are wheels, frame, forks etc, as they are common to find them now
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