♠️ M77
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Hey Wellsie,
Only the 250cc , it uses a chain that is off a suzuki , it shouldn’t need replacing unless the bike has had a hard life or its around 50k old ish…
However , the “tensioner” on the bike is automatic, that deals with the tension /& chain stretch as motor spins, the tensioner is usually the “first item” to replace as they do wear out more than a cam chain does.
One way of checking the chain is to listen to it as it spins on the motor.
another way is to remove the top valve cover- inspect cam sprockets for wear (the teeth eventually wear down)
- touch the chain, if it feels saggy , it could be sign the tensioner is worn or the chain may need replacing
the service manual only has this information about timing chains.
if the image doesn’t go full screen when you click on it. Save the image to your PC or Press & Hold on your Phone to download it.
Hope this info helps!
what can I use to clean my exhaust I got black grit dots stuck on it
Some wire brushes, very very fine sand paper, then sponge etc = Use AutoSol paste on the parts that are rusty 👍
Spray ACF50 on the pipes , a little = leaves a nice dry layer when exhaust warms up , should help it stock more salt attacks on it.
Im going to try either tomorrow or sat when its dry is try force to turn it from where it connects to carb with pliers which im hoping this does work as I be out of options
Remove the adjuster off the carb.
Get some wd40 to soak for a bit , then get mole grips
Bit it hard , then turn left to force it to undo itself.
The road salt / muck near the front is what causes them to seize. Not always easy to get on their own.
Also, get some ACF50 or grease –> spray in to it , so that it will keep the area lubricated.
Hey,
I received your email regarding this exact topic – So I’ve replied back to you.
Hope this helps.
Hey!
You may have hit the nail on this one , as indeed *C* without digits doesnt seem to indicate any actual fault.
You may ride as usual but just keep a good eye on all parts to ensure nothing rattled loose under braking?
Dare I say though, what if you checked your brake switches arent loose or attacked by weather?(rusty contacts). Hopefully thats not whats causing them to act funny under a full brake (where bike even shifts its weight to brake force)
If this was a different brand, i would have guessed it was something to do with an ABS system and ECU talking to each other (something’s a bit off but not to panic yet?)
As for Hyosung usually the ECU will tell the exact code (eg. D45) if some device is failing or acting intermittent.
But i hope this bit of reply helps & hopefully its just nothing really👍
But update us if something changes or If i missed something.
You may also disconnect battery for few hours or overnight max. It may or may not force the ECU to reset the C code. (There isnt a lot of research data ive collected yet on GV650 EFi/Ei’s to see how effective this is. So you may try)
Do I start chucking money at it!?
Probably,
The bike still isn’t happy = Look at your own spark plugs , will tell you exactly if its electrical / fueling / or poor air system. (Rich vs Lean vs Poor Electric Sparking)
Bike will not ride perfect unless all 3 work in tandem (air / fuel / sparking electrics)
I would read my replies above ^ on this topic = write down as a list. tick off every single checkpoint.
Fueling Parts & Carb OK & checked over? = then we are done with the carbs.
Then the electrics or plugs would be your enemy , I would go here below …
(GV125/Gt125 = same engine, same carb, same coils = same behavior)
(Follow my replies in those threads, as i go quite deep on electric dramas & HOW to test them yourself)1. https://hyoriders.club/forums/topic/gt125r-no-power-between-4k-8k-revs/
Yes,
Faulty Coils & Regulators happen to all hyosungs. They are just a cheaply made parts that die out eventually. The japanese win when it comes to electrics.
— > Could also explain your plugs not doing their job or otherwise fouled/annoyedRemember this always:
High revs / RPM needle stuck high / very slow to drop revs down = Air Leaks (anything air flows thru) or CV sliders stuck or choke is not off (still on choke)Boggy / Jumpy Revs / Laggy = Electrics (inspect all including plugs , can’t stress spark plugs enough) or Fueling Drama (anything that petrol flows through)
So had another quick look at the bike, I took the air filter off so I could access the carb. I thought I would start it up just to see what it was like and in my opinion it ran better!? I also noticed some black bungs at the bottom of the carb, so removed them to reveal screw heads. What are these for? Also choke is working better with air filter removed. Do I have a mixture problem here? Any help would be appreciated
Shane
Bungs hiding gold screws = Air / Fuel Mixture = Only the factory tunes that. Dealers are told not to touch it whatsoever , otherwise re-tuning is a serious abyss here. I agree with the koreans.
If it runs better without a filter = Investigate air filter (clogged?) or spark plugs (glaze brown means they are healthy)
Glaze brown plugs also mean = carb / filter / electrics are doing well.
To increase mixture = Either add 1 step up from a factory main jet (90/92.5)
Pilots remain size 15 each but must be clean = smooth rolling idle is dependent on pilot jets
Again, investigate your black CV sliders on the carb
Idle and revving up to 7k rpm etc = they slide up
Dropping revs to idle = they slide downParticles on the slider will grind against the carb walls = certain rpms will be bouncy, certain rpms will be jerky –> carb sliders may be hanging
Cleaning them fixes this.
If the sliders are “retracting” fast & (as quick as your throttle moves) – they should be working on
This clip will hint , why its critical the sliders work nicely … (idle , through gears , warming up)
The real key to a free flowing bike is to attack these at once:
Coils , Spark Plugs , Clogged Jets , slow retracting black tube sliders, good fuel pump working , air filter is new (PAPER FILTERS LAST 2-3K before they start to give you less air for carbs)
5k would be pushing it.If its a fabric / cotton gauze filter – it generally is okay until approx 7-10k , the filter will hint how dirty it is.
———————
“UNLESS” – Someone in the past ever messed up the mixture screws (which were hidden behind black bungs) , then it can explain cause not mixing air intake & petrol properly inside. Like i said, it would be an abyss to retune it back as Koreans never revealed the adjust settings, they do that before shipping the bike away. Depends on country & market its going to.
So the home owner, may go through few spark plugs until its right (plug chopping business)
But honestly, the spark plug colors will tell you how rich or lean the bike is.
Took the bike for a test ride but it feels like it’s not fueling correctly. As it splutters them revs back up as it should. I had to replace the fuel line as original lines where perishing, but the fuel line is a little to sma I think. Any ideas to what’s wrong. Everything was free and moving as it should on the carb before putting back on to the bike.
Cheers shane– Pilots = affect idle and slow moving , so pilot jets should be clean
– Spark Plug – Clean it , with that carb cleaner – it should spark better, if not IX or Lasers will wake it up better (& bog less under some load) – Stock plugs are just that woeful.
– Fuel lines – Ofcourse, adding thicker high temp lines only add to “more fuel in the pipes = bigger hole” & “fuel is colder = less misting on hot temps, comes to carb as liquid than a misty hot gas)
– Main Jets hopefully should be cleaned up too.
– The “BLACK CV SLIDERS” are critical , they are the mother of the carbs , so you want to make sure they “retract” up & down fast without any delays – that means there is no particles stopping the Sliders moving when you add revs to the bikeWhen you rev , they slide up – they must not delay whatsoever.
Hope this info helps!
Hi I was looking at exhausts. However contacted backwidow and they direct me to the fuel injection type exhaust however mine is an 09 carb model. I am struggling to find a new exhaust for mine and mine is dead it’s been welded however badly corroded and needs new system. Have a new silencer on it max torque can.
Hey!,
I wouldn’t panic – “All years” of Carb & EFI vTwins of GT250R & 125R use the same pipes. Same fitting too.BlackWidows makes the pipes for Carb & EFI , yes correct , but they will send you a “blanking” bolt. Call them and ask them to make sure a blanking bolt is included.
Refer to the image below:
Having said, this would also be the case with Scorpion or MTC UK exhaust companies – They must send a blanking bolt for carb models , if they send you EFI pipes
If you need a stock/standard pipe system that is in a good nick , please call “Startrights Leeds” & tell them this:
Looking for a standard exhaust system for GT125R , in used condition – Marcel says you have the orange hyosung for stripping (I sent you)
They will discount it for you & post it direct. 👍
Their website -> http://startright.co.uk
Good luck, welcome to the forum!
Also, as the RC is 3.5K
Stock clutch may be ok but probably due soon but if youre looking for a better clutch , this site does EBC UK plates & race springs so get more out them and a good torque boost on hills too guaranteed.
Its at /shop/ section of this site. I know no one at all doing race clutches for 125s except myself , our own local UK dealers only do expensive & woeful china plates. £20 a piece!
Id stick with the trusted EBC brand & Suzuki bits 👍
Ahhhh,
Carbs hence i left it as last haha. There is some discussion about this too on the FB group too.
The service manual actually forbids workshops or dealers from tinkering the air mix screw.
Hyosung never revealed how to mess the air screws simply because it would be the abyss to get it right again!
(Lots of plug chopping & re tuning)
If the carb was lean all he had to do was increase main jet 1 size up.
90 n 92.5 so bike is less lean more rich without messing the air screw.
Stock is 87.5 n 90
Dark brown is good! Should be lighter brown all round , suggests to me that you may need more air (filter upgrade due?)
More fuel = more air to mix 👍.
If you search *carb* at the top ,there is a tutorial on jet swapping which mentions more detail on sizes and why we dont need to change *Pilot Jets*
Just *Main Jets* usually only upgraded thats all.
Sooty exhaust may indicate a weak sparking behavior from magneto/cdi? – or else you need more air or the jets are too big (or air/fuel screw ratio off?)
Your mech owes you to fix the carb since he tinkered with it so it must give us a good result?
A little soot is a ok but caution ofcourse how much soot is there. Too much aint good (hint = bike spits raw fuel on cold warm up)
If the carbs are cleaned thats brilliant but did the mechanic clean the CV sliders (the black tubes) they are the mother of the carbs , defo must be zero signs of particles then they slide & retract nicely
(Slider behavior -> Up n down based on your revs => they release JET needle up n down attached to it)
Usually touching carb sliders. Push up by hand and you will see them retract very fast & same pace , no delay or getting stuck = thats a hint of health there.
So battery works. No dimms. Seems to hold well.👍
Did you strip down the bike plastics? And then look at every nook n cranny near the intake system n carbs to really be sure its leak free.
Whatever bolt is on carb n engine must be *tight* = hot engine can make things flex like rubber boots (like taking a gulp of air) the clamps must be tight so it doesnt leak out even a small hint of air.
Last not least, confirm with yourself that all exhaust bolts are tight. We loose power on a leaky exhaust system too.
So to put in short, we are checking intake system , exhaust system for leaks. Re investigate the carbs , jets , air filter and including the black CV sliders in carb bounce nicely (critical)
Keep us updated , we can do all we can to help the bike 👍
Good luck 🔧
Hey dude
The CDI cheat never works on a 125 – whoever said so is a faker
“A few” 250 cdis allow 1 wire to be cut – which helps the 250 engines rev slightly better on its STOCK coils.If you had upgraded the electrics on the bike, it should be very spirited by now.
Sadly, as i’ve experienced fixing customer RC bikes the 4-7K rpm issues is usually caused by either of these:
- Ignition coil isn’t getting 100% electric juice (suspect = cdi / magneto )
- Spark Plug could be sooty (trust me! – RC bikes do not tolerate sooty plugs more than the old gen bikes & electrical changes = RC bikes have some woeful EFI electrics but i digress!)
So –> Sooty plug = Intake issues / weak sparking ? / fouled plug (annoyed plug) - Air filter needs attention = more air is sucked in as you go faster but the carb likes a clean filter & not restricted to less air flow than before
- Clutch needs looking at (any RC over 4K must have a new clutch set as the cheap organics wear down fast –> hence the gearbox drama and false N’s)
Search “Clutch” at the top of the site which explains what kind of power issues you get on a clutch that has worn down a bit (Symptons) - However , we can’t rule out a weak spark or a misfire – Make sure the “HT” cap is under 7k ohms – > RC have an EFI HT CAP for the spark plug that is not that much better than 2007 however too much ohms –> weak sparking -> delayed RPMS
- Intake Manifolds need investigation – > you need to take out the fairings and possibly the carbs off – then inspect your intake manifolds – there should be zero holes or zero leaks (protects piston rings from dirty particles being sucked in too)
- Battery – If it isn’t 12.8v fully charged when off = inspect magneto , all electric juice starts from there before it feeds the rest of the bike too.
If you also switch full beam –> engine off -> indicators / hazards on –> if the dash “DIMMS” -> check battery is holding up juice / not dropping volts too quickly (battery should not discharge quickly) - intake lines (vacuum) – only lose clamps can cause leaks or a very old “stock” line that is rotting inside Vacuum performance is needed for the fuel pump & fuel tap to be effecient in high revs (4-11k rpm) (more demand = more fuel). Big lines help the vacuum & fuel system to run a bit better (colder air/colder fuel) on a hot engine.
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CARBS!
i saved this for last as it’s usually a time consuming process but you may need to inspect your “black CV Sliders” inside the carb and clean them
CV sliders control most of the carb work, so as you rev the bike , the sliders go up , they release more fuel!If the bike is hanging at certain rpms or stuck at certain points –> CV Sliders in the carb need cleaning (common) , Clogged jets in the carb , float bowls need inspection to make sure they are all at the same height (not bent floats)
When you look at your own spark plugs , thats when you get a true story of whats happening to the bike. A healthy motor = all coffee brown color , no black anywhere.
Spark plug color hints = (Intake system / Fuel System / Sparking Electric system conditions)
So it’s a case of verifying what i said above & most times some TLC on the intake system & carbs wakes it up. Electrics are common on RC but not impossible to fix, if you have upgraded electrics , that’s a good thing Less drama down the road!
Let us know how you get on, or if i missed something too.👍
Also have a look at this , as some of my replies can apply to your situation too.
https://hyoriders.club/forums/topic/gt125r-no-power-between-4k-8k-revs/A stock filter has a cone inside and the material is different = restricted.
Also it’s a bit smaller than K&N –K&N can push 3x more air = cotton filter in oil coating – so cleaner bike & more free revving yes. “650 specific” K&N is good otherwise , BMC Italy does it too (known for race filters on aprillias) – I owned some BMCs in some of my bikes , some K&Ns – they do the justice
However – an upjet is mandatory (hence carb tutorial on the forum goes in better detail on jet swapping – just search “carb” at the top of site.
Running 3x more air on the same stock jets = engine is much hotter , misfires , new piston rings soon lol.
Likewise, if you have a performance exhaust pipe –> more gases going out –> upjet is mandatory
Any air upgrades basically (intake or exhaust) = upjet
I live in Surrey not too far from Box Hill, Newlands Corner or the Ace Cafe. Anyone near with a GV Aquila 650 it would be nice to meet up to compare bikes, mine seems to have clunky gear change but is it normal or a problem that needs adjusting.
Welcome!
In 2019, our meets will be near the south UK – You get a chance to meet the lot of us that spawned from the facebook group lol. I have seen a few 650s up north, but not sure how common they are on your southern region – so will have to do a nice map one day!It would be a good idea to head to “Technical Help” section of this site and get a 650 service manual that matches the YEAR of your bike (but most are the same anyway!)
It contains instruction on the best way to “adjust” the clutch cable so that when you “squeeze” it it doesn’t feel clunky to shift up.
It is common that some various hyosung models (125 / 250 650 ) have a clunky gearbox usually caused by either:
– Cable loose or too much play somewhere on the line set up
– Thrust bearing on the clutch basket (if it’s very old & never changed before)
– Bad oil or oil too worn down (cheap oil) (especially when the oil has “worn” down badly, it looses the smooth transition effect on bike) – Manuals generally stress to use premium oils anyway.
– Clutch Springs maybe too old (eventually, hot heat will cause the old springs to fatigue)
(hence its obvious when a gear change isn’t as “snappy” like it was first new)But hopefully it’s just a cable and the adjusters that need sorting that’s all. 👍
Oh yes, it is common!
Hi Guys I’m looking to upgrade my main jets and do a carb rebuild at the same time. My GV125 had been stood around for sometime before i bought it, in saying that i got lucky getting it going but i know it needs attention very soon. I’m looking for the correct jet size and a rebuild kit for the carb’s. As well as this I’m after some tutorial on how best to remove the carb’s as it was a nightmare the last time i done this and don’t want to struggle unnecessarily. Its fitted with straight through ss exhaust also, thanks in advance Shane
Hey,
If your local dealer doesn’t have genuine Mikuni jets / EBC ones , you may send me a message as I for sure keep a stock of older genuine (on ebay) & some new jets.
I usually send jets with air filters on some custom orders.I have dealt with the GV bikes a few times, one thing is for sure:
– Pilot Jets do not need upgrading at all.
– Stock main jets are identical (87.5 front / 87.5 rear)So a good upgrade commonly is the “90 Main Jet (Front)” and “92.5” (Rear)
Ofcourse the rear is bigger as its the hottest engine, so a bit extra fuel at the back has a cooling effect & slight torque boost in 5th gear.If you head to Halfords or EuroCarParts – My fav cleaner for carbs is WYNNS FUEL SYSTEM CLEANER – It’s a green can , ofcourse any good carb cleaner will blast every hole clean.
Also , i must stress a little here – The “STARTER JET” (which can’t be removed) has a very very tiny hole , ensure you have a good carb cleaner.
After the STARTER JET (that big metal tube that you can’t remove) is cleaned up, your bike will start a LOT faster.
Starting / Cranking = Starter JET
Slow Ride / Idle = Pilot Jet/Main Jet
Normal / fast Riding = Main jet.1 more thing. Head over to poundland & get 3 cans of AIR DUSTER – When the jets are dry , use the air duster to blow the holes clean.
Use the air duster to blow everything inside the carb, after it has dried up from a carb cleaner liquid.
A full clean will really do wonders to the bike. Good luck!
so it just simple as getting a bolt to push into the tube and clamp it
You got it! That’s it.
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also I just found mine as a fake egr but can I leave it installed as it is or does it after be blocked just if it doesn’t make a difference I was thinking of just leaving pipes connected to it saves me the hassle getting stuff to block the pipe etc
These links may help.
https://m.facebook.com/groups/345623961212?view=permalink&id=10154901704736213
https://m.facebook.com/groups/345623961212?view=permalink&id=10154883738251213
That device is for euro tree huggers. Very early GT/GV bikes didnt have them.
Put simply. Bin it = bike is a *little* more throaty and gets rid of pops.
Very common mod on 650s. The forum has an EGR removal toturial for 650 but principal is the same on 125s.
It is as useless as the sidestand switch 😉
I’m guessing the centre pipe as a splitter before the t junction
Just repeating what was on the 2D diagram but in another way to explain it 👍
INTAKE MANIFOLDS. (VACUUM ROUTING)
=REAR HOLE 1 = Fuel Tap (small port under tank)
=REAR HOLE 2 — JOINS WITH —- FRONT HOLE.
(In other words = Rear #2 & Front Hole are joined with a T PIECE junction.)
Front intake boot always has 1 hole.
The back has 2.
The vacuum pump wants both 1 rear and 1 front to work properly.
Tank Tap goes up un 2nd extra free hole given by the rear.
Uprated Japanese 520 Chain & Sprocket Kit wont this mean chain wont last long on the adjuster
A proper Jap 520 kit will beat any expensive 428. You won’t need to touch the adjuster every day like a stretched 428!. Just keep the chain nice & clean!
IF you go on the facebook group, type in “chain” or something. You will see endless complaints of SNAPPED 428 chains (mind you our bikes are heavy too).
520 sprockets will outlive any 428 sprocket & is wayyyyy harder wearing👍.
EBC “Heavy-Duty” Clutch Plates Friction Drive Overhaul Kit – Hyosung GT125R GV125 GT125 XRX125 RT125D GA125 do they have Kevlar or are they stock
The product page describes the brand it comes from, generally kevlar is good! – The stock ones are just cheaply made (and MORE expensive from any dealer)
This site will never do stock gt125 clutch plates. They are that woeful lol. EBC & Lucas win!👍
