♠️ M77
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Mini update, so I’ve now got it a lot better than it was, she now starts every time and everything, its just that sometimes it will pick the revs up for no reason and I don’t really know how to describe it, its just as if it has a mind of its own and its really weird, open to any suggestions if ya’ll have any
Air leak? (entire intake system right down to the o-rings)
Cloggy Pilot Jets? (hunting for fuel)
Depends what revs and how far low it dips or climbs to?[moved to technical]
Hey,
M815 GT250 | M815 GT125 | M795 GT125 are fine to use. The 125cc engine doesn’t care which one is used as they do the same job.
If you take out the spark plug and place it on the frame or engine bolt, and no spark is visible, then attack the following:
- SideStand Switch (Cut & bin it) – Then bypass it (wires joined) & tape it hard from water invasion.
- Clutch Switch (at the hand lever) – I wouldn’t bypass it, but it can cut sparks even while its running. A multi meter will say 0 ohms if its dead (whenever you press it or let go)
- Neutral Switch is lit up on dash ? – The plug is above the sprocket cover near the shock.
- Go to your Magneto/Stator => Find its blue/green plug => probe the pins with the multi meter => it should say around 80-100 ohms healthy. Bike won’t start without this thing.
Second stage, involves your ignition coils (common failing units as they are cheap built)
- Unscrew anti clockwise the “BLACK PLUG CAP” away from the HT LEAD
Put a meter inside both ends, tell us how many ohms it says under 20,000
(20,000 or 20K on your meter display)
Do this for front and rear. - Since the “COIL” on the frame now has an exposed “HT WIRE” … => Put one wire of meter there (red) and also (black wire of meter) on the FRAME (unPainted surface or bolt)
It must be under 6,000 ohms healthy (or 6K on your meter)
Last thing, it’s still the coils… We are checking the “terminal pin” next.
- Switch the meter to under 200 ohms (the lowest figure on meter)
-> Red meter on the “TERMINAL PIN” of coil
-> Black meter probe on the “frame” (ground)
==> Let us know what it says ?
Let’s do these before we dive deeper in to the bike, hopefully not though! – You can copy this reply and re-write it with your answers in numbers , so its easier to see each device i mentioned is in spec according to the books.
Good luck
Hey,
Welcome, check out the links below (1 for fuel) and 1 for air set up.
https://hyoriders.club/forums/topic/fuel-lines-hyosung-gt125r-gt250r-carb-hose-diagram/
Hope that helps! 👍
I’ve looked at the GA parts book, it just says ” 31800-35C00” – Starter Relay (Various Hyosung bikes)
Are you able to attach a picture to point to which fuse you came across? Hit “Add media” to upload a quick one.
Some folk use wemoto, i can’t comment on their quality , could be taiwanese as they seem to do a lot of china stuff (cheap pattern-copy parts)
I buy many jets in the trade while i fix customer bikes or they go with the K&N filters that are stocked now. The jets can be sold on their own, you can message me next week as i am due to list them on the site as standalone units starting with Pilots first. They will be EBC ones (UK) or Keystars (Jap) , I wouldn’t use unknown jets , incase they are fake brass or their ofrices/holes are not drilled accurately (90 isn’t really a 90 etc…)
Check my ebay over the weekend, I have stripped a couple of 250 & 125 carbs , so will put their jets up as 2nd hand listings. Most are still the original mikuni ones.
If you had a hyo jet and it didn’t fit, consider the jet-holder tube may have damaged threads, possibly also.
If we search deep enough on the web, there is anough complaints even on facebook, where everyone hates the hyosung stators that seems to fry things sometimes.
So i wouldn’t personally put hot grips, they won’t be that hot to be fair as the GTR has a solid bars (it has to heat that solid metal element too) & contend with the wind chills. Some grips draw too much current (*amps/watts*) and is noticable when bike wanes a bit in terms of overall electrical supply to other parts of the bike including keeping your battery charged up.
Go checkout KIES HEATED Apparel, you can wear thin layer gloves that are heated by a small power bank they sell. or Heated bike glovses that can be hooked to a portable power source.
That leaves the question of stators producing power for the bike only, dropping stators from Kawasaki is common, if it isnt from Electrosport. Pays dividents for some 👍
Rear axle wheel I usually tighten around 80-100 ft lbs, it should be in one of the 650 service manuals on the last pages where it gets technical about what torques wheels and ancillaries get tightened at.
That thing is called the fake emissions. You can bypass this by BLOCKING pipes that FEED it.
1 goes to airbox unit
1 goes to engine cylinder
1 slim pipe from the intake manifold
^ those 3 above = stick a metal bung or bolt and clamp it hard. EGR bypassed. The engine won’t even miss it.Now we have less chaotic pipeline to work with 😉
The 2 gold bolts come out, lift the fuel tank , and stick a prop or stick that holds the tank temporarily! (use caution as its weighty)
Now you can just about see the pipes going to the “frame mounted” ON/OFF tap.
Put the tap to OFF. And disconnect the TANK (& block the tank with a temporary bung/bolt.
Put the tank aside elsewhere.Now you should have a clearer vision of the AIRBOX. Don’t rush to attempt to dissamble it, even myself still have to fight with GV125s , if i don’t drop the engines to the floor. Other lads also mention being slow and sideways in to the way you do things. Check this post out below, there was a discussion about a while back.
https://www.facebook.com/groups/hyosungowners/permalink/2536632946556232/I’ve heard in the past the owners left the box connected and just undid the carb bowls while sat on engine , even diaphragm covers on the other side, while trying to swap jets and using small compressed air to blow the carb through, never tried it myself personally.
I just know the manual says to take the carbs off completely off bike and then use air blast or other carb cleaners. I know the intake manifolds will be very soft , so probably another reason i rarely mention to do things while carb is still attached to engine and airbox with only its undersides exposed lol.
Once we get past the tank and airbox coming out 1st, then you can follow the tutorials i made (here) and (here) , that show fuel line routing and air pipe routing. You have a manual tap, so you will be skipping some parts that don’t apply to you & 1 less pipe to worry about as GT bikes have more anyway , dare i say.
I’m about to head off to bed, but i have an EFI version here and rode the carby 125 before , believe me…..I understand you clearly lol.
Click “Add media” in the reply box, to attach some photos so we see where you got stuck at ?
If the bike was in Korea for whatever reason or warranty work etc, the engineers would have to drop the engine to the ground, so that the airbox can be removed.
125s tend to have certain “security” torx bolts on some things like box, exhaust pipe etc, to stop owners modding & keeping the warranty i guess. They are the MOST ANNNNNNOYING bolts to undo sometimes, i pray you don’t have any seized torx bolts as 2016 is young.
In terms of airbox removal, I can understand your mechanic , we don’t want to add any more stress to the intake manifolds as they are very very hard to order new nowdays.
Based on what you tell me with photos and I wake up tomorrow , i will check this post out when i get the chance to .
The gist of what i’m saying here is
// Factory = expects to drop the engine down the chassis to access box n carb due to frame-bar in middle.
Owners = bit of a gentle , i mean gentle but lots of swearing , its a tight packed & strange design that area .While you have 5 mins to spare, check out the forum a little more i did various tutorials on carb modding and line setups , though they were done on some client GT bikes but principle is the same for GV as they use identical engines.
Moved to “Technical”.
If you also go for a fast sprint, then all of a sudden the bike comes to a halt. Attack these below:
– Fuel Pump (open it, check for dirt)
– Clogged Carbs (plugs will look glazed white if its too lean to run top gear all the time)
– Because of leaning running (i hope not), the plugs will go as hot as they can then they slow the bike down by force.
– Check that floats are 7mm tall , crucial for everything. (Carb will be upside down on table & measure float height)
– Check vacuum system is tight and good (Intake O Rings, Intake Pipes, Vacuum Lines)
(makes it very hard to start 125cc Hyosungs with air leaks)
– If you filter is old, consider changing it, it may reduce fuel flow if its bad.Let’s try these , before attacking anything else on the bike. Good luck and let us know.
Hey Steve, I should have copied the event details on to this site, but we appear to have some numbers in
So i will announce it forum wide shortly.
https://www.facebook.com/events/614745452676467/The event is a Meet & Ride that’s happening at Rochdale Lake (Wine Press Inn) for a rideout to the holmfirth valleys.
I wouldn’t know a specific far-north-east rides now (ie. Durham) per se, but a lass drummed up the same question on FB, seems like when the weather is warmer i may go up there , for an impromptu mini ride lol. Though im in Yorkshire already anyway
What do you think of the event i mentioned ? That’s the official one , if everyone makes it, the better 😉
I have ordered a regulator from Electrosport, and retested the stator and It does say 55v across all 3 pins…
I’m slightly worried though…
Would you say the regulator from Electrosport and the stator I currently have, which “looks” taiwanese be compatible?.. the last thing I want to do is put a the new regulator on and the stator burns it out for example…
I replied to your email, and yes I would say the stator may either take the reg with it (as it’s not able to regulate what your stator is doing so to speak) or a fishy regs takes out a healthy stator vise versa , so the 2 are kinda like a married pair for the charging system . Stator is also part of ignition system anyway also so it’s “blue and green” plug flywheel trigger sensor will be around 100-110 ohms healthy for factory ones i believe, when bike is turned off.
If you struggle on amazon or something I can always send one just email me and will supply correct ones.
The ideal regs as before
– shingden for hyo , involves splicing , popular in US.
– another brand to check out is Electrosport n i own one on bike #2 for years. I do them sometimes for EFI machines as i have a GV250 Efi as test bed. 250 and 650 need same readings anyway and tend to share regs.The service manual prefers the bike does least 70v at 5k revs. Optimal is 85-99v.
Reg will report 14-15v optimal with a healthu battery.
Consider your stator is not saying 55v across all 3 pins? Thats asking for a change by sounds of it.
Pops on exhaust can be a sign of something going on with the injection system if it sounds like misfire.
The true way of checking is by a mech usually get readings on meters on certain devices as how the service manuals instruct them based on what issues the bike makes.
I would consider again your exhaust system. At least go back to the stock filter and exhaust temporarily as it will be easiet to diagnose the bike without mods just yet.
You can message me in 48hrs as i will be listing one on ebay as i am due to strip an efi bike soon.
Genuine ones last better than china copies but they want to be covered from water end to end and the spring tip has a bit of grease inside it.
You are correct, the efi bikes all have the intake sensors to know air system has changed from the ecu’s settings, the ecu isn’t going to “upjet” the fuel so to speak.
i believe the stock filter is a lot of air already since it shares the same filter with certain GV650s. Some have huge holes compared to the carby era.
the exhaust lambda sensor is on the pipe , i would advise the exhaust system has a baffe hole about 5cm , huge holes won’t work or its too free flowing , you want to be as close to the stock one as possible and you won’t be triggering the ECU , you may miss the noise but thats the life with an EFI bike.
Hyosung didn’t sell any mapping kits for the general public, i don’t think its something they would do , although it may make life easier for us experienced mechanics when it comes to fuel mapping etc.
Try the stock filter and consider the exhaust set up 👍
I’ll be honest to say the pics look like you may have taiwanese copies of these things which are just as lethal, so may not be a true mosfet type reg or genuine hyosung stator (though they are woeful too)
Shingden is the common reg upgrade which involves wire splicing etc, so it wont be too cheap either but its better than the basic shunt types Hyosung uses & some ebay copies. The 2nd also (which one of my bike uses) is the Electrosport brand from US, good regs and stators they make.
You can always message me to get the ones listed on this page which then includes the mini conversion harness, so you pretty much fit and fire away. I’ve done this for EFI bikes since their regs have different outlets even their stators vary!
Test your stator and hope it is producing, as this will be a longer road to replace you the correct one , as it depends on: Year of bike, what the flywheel LOOKS LIKE inside, and which stator in the database i can look up to match it , though i’ve been doing aftermarket stators for the smaller bikes , the 650 folk usually upgrade to a kawasaki stator if its a carby bike as its easier to put simply , though maths & research work is involved going this route , it seems to have paid dividents for a few i know.
Cheers Marcel Helpful guide for a beginner mechanic like me, any chance you could post more servicing tutorials like these?
I did a few including pipes, fueling, carb jetting, side mod , clutch, and im welcome to ideas ofcourse ,i got other drafts, i just make sure i do them in plain english for all to follow 😉 ,
We don’t know what brand or part numbers the stator n reg came with as the 650 uses various with the GV sometimes or wrong one was fitted causing it not to recieve magentism from the flywheel to charge up the coils , we don’t know till they confirm specifics . I would still test it and your mind will have the answer right there if its producing or not.
Thanks for all the suggestions Marcel, no idea when I’ll get another chance to take a look given work and family stuff going on but either way I’ll let you know how it all goes. Tbh both the coils look quite corroded but they still sent quite a healthy looking spark to the plugs but I’ll go through and check it all out like you said plus all the vacuum pipes and valves ect. Hope to be back on the road soon and get you some lovely pictures of my girl all clean and shiny
You ain’t too far from me , i may be in Lincs when its warmer, so we may go for a sprint if she is ready or meet us in rochdale for march meet 😉 , event details on facebook or ill post info soon on this website over weekend im sure.
As long you take your time to address each part , we should expect progress , good luck
Hey,
Strip the carbs again, remember the brass tube with the tiniest hole, yeah thats the starting ports used for starting the bike, even compressed air helps blow the holes clean through trust, its very very very small lol. A single strand of a headphone wire should be able to go in and out.
Do this with pilot jets, take them out and make sure light shines through the holes.
Put the carb upside down on table (floats facing the ceiling) get a ruler and make sure each float is 7mm tall from the edge of the carb bodies or adjust , these control fuel flow so its very crucial or you have too little fuel to begin with (floats closed early)
Fuel pump at rear = open its cover, you will see the insides are okay and close it back after clean , it rarely , rarely fails but a bad filter can let particles go to your carb n pump making 2 issues than 1.
Check that vacumm pipes are sealed good, also the intake system , it will take few annoying cranks to start it if there is even a slightest air leak. Since you had the carbs off, check that your manifold O rings are okay (go to /shop at top menu to see what i mean) , then we can rule out a leaking intake system causing start related issues and does affect idle big time.
Clean the spark plugs, but if they are old or show signs that they are fouling easy , maybe consider new plugs and try again , your ignition HT cap will say 7k ohms on your meter with the other meter wire on frame as ground, suggestive that your coils are okay
or coil terminal pin (spade shape behind coil) and frame on your meter will say about 0.6 ohms strong. (less than 1) , coils are assumed to be okay and should spark just fine , weak coils affect starting and idling too.
Hope this info , and welcome . i probably also covered some things in more depth in other forum topics too.
