♠️ M77
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Hello, the orings are installed by mikuni japan when they make the parts , hyosung just puts the carb together to make twin carbs.
However, the oring isn’t critical. The bike will be okay without it. It does help guarantee extra seal between the Jet Holder and Main Jet. But a tight clean jet won’t leak , just don’t over tighten it as brass is very soft
Regards!
After doing tuned up bike runs fine gunna keep old coils on till my new caps come
The NGK caps came with the factory fitted HT wire so don’t remove it. Deal with removing the black wire from the actual coil instead
as for updated coils, if they spark blue/white , they work as they should. Yellow spark just means the electric system is weak.
Owning various hyos myself i know full well the new shape 125s are quite picky when it comes to weak electrics , very veru moody starters but otherwise if everything is cool , they work fine and just ride away!
Hey,
The bike is VERY lean, almost dangrous to the piston rings (if piston rings start to wane – you compression drops bad and it will never be as fast as it used to be)Heat also makes the valves tighter clearance wise , so ofcourse that will mean you will need to do valve clearances much sooner than later.
Now then, let’s deal with the fuel situation….
– Do this mod below or let your mechanic do it[Tutorial] How to adjust Carb Slide Needle (Tuning) – Hyosung GV & GT 125/250
It must be done.The plugs have a sooty black ring, it suggests the carb does get some fuel to idle.
The white center is very white, i mean white! – that means its not getting enough fuel when you’re “riding – whatever mph on the street”.
What jets are in it ? You should have already fitted the jets i sent you 90 and 92.5
or 92.5 x2
or 92.5 and 95 (max)Also if you or anyone has ever touched the carb, please ensure the float height is 7mm (not less , not more)
If the float height is affected in anyway , it will affect “riding, idling, starting” .
Follow above early replies for intake air system as extra air leaks near the airbox or manifolds or manifold orings will overheat the bike a bit and lean out the plugs.
Your own air filter is fine , that’s why i did not mention it. It’s brand new.
See how you get on fella, keep us posted 🙂
Furthermore,
E. Electrical.
Clean the laser plugs hard. = Do A to D first above before going for a test run with clean spark plugs
– Then take them out.Take 6 pictures (threads of plug, and also the middle of plugs) – Then i will assess how your bike is burning fuel. I will know if it looks like either air or electric or fueling is a weak link.
I will also quote a picture for you from the service manual that mentions other reasons for a speed drop. Remember a brand new bike does 82-88 factory , i have various hyosungs so i tend to know how they are!
You got this!
Hey,
It looks like you have a standard exhaust on it too, i will assume the bike is very young,A. is it under 5,000 miles miles ? and do you have any proof history of these 2 critical jobs (as Korean’s mention it on service manual if the bike speed drops)
- Valve clearances done and shims changed ?
- Compression test ?
B. Also since you changed the coils and filter, your speed will drop also again if you;
- Changed the Jets yet ?
- Clean the carb with air compressor (must be done believe me) or ultrasonic bath.
If using a rattle can carb cleaner, you will probably go through 4 small cans.
C. Air System checks (because you changed the filter)
- Spray the carb manifolds to see if revs change (speed drops also if the orings under the manifolds are caked up or too old by years not miles)
- Spray under the air box holes where carbs sit on, if revs change, you have a leak.
D. Fuel System
– If it’s a 66 plate. Korea says change the stock lines and the filter after 4yrs (whatever miles she is on now) – Old rubber can rot inside, old fuel filter can cause weird issues, it’s mentioned in the service manual. – Change lines and use a giant fuel filter that’s trusted , not china things. Lest the carb gets clogged up and your fuel pump won’t push hard if you want to ride faster
– Open the fuel pump, clean it with carb cleaner only .Do not use compressed air, as it has spring loaded mechanism inside.
– Fuel Tap that’s directly under the tank —> It should work as normal. If using a big filter, when you stop going for a long ride, you will ALWAYS see half-full or 3/4 full filter means the tap is working. Emtpy filters after a ride always suggests starvation is likely.
– Use e5 fuel only. E10 will cause a lot of problems even as much as bog downs , eats up manifolds eventually, eats up rubber bits, extra ethanol in the e10 can be corrosive to metal parts etc… it’s just a devils juice. Stick with E5 and use WYNNS XTREME GOLD (this brand only) from halfords , pour all of it in a 3/4 full petrol so that it will soft-clean your whole fuel system (it will try!)Hey,
Please ring startrights Motorcycles Leeds and tell them marcel sent you because they are one of the oldest hyo dealers and sometimes as a trader myself i buy half their stocks for my own business.
If they can’t help , send me an email and i’ll see what i can do , i have other trade contacts to get parts from.
💯❤🏍 Happy for you! – I like stories like this. Glad it’s all good and now the rider can enjoy the bike for what it is!
My local man , i will bring the 520 chain set to you, hello Yorkshire! – If the weather isn’t great or im too occupied (mechanic work!) ill still post it to you.
I do hand deliveries when people are in the yorkshire boundaries sometimes, i will update you.
Glad the bike is doing you well 🙂
I make / refurbish cables (please dont throw away your old one, they are handy donors!) , i have an old one that’s like 5000 miles old on a 2016 donor bike, also i can get one via the trade for you, so just send me a PM on my profile or use this /contact/ section here if you want.
So all good on the battery side of things now ?
Also how are the new plugs reading okay ?Mikuni Pilot Jets screw in , as well as main jets , but show us the picture of the carbs next time they are open and at least you will see the sizes for your self in there.
Sadly no and no one is going to genuinely advise putting a 650 inside the 125/250 chassis , it will destroy the frame. We need you alive sir 🙂
1. Ride the bike as it is with the pipes , but make sure the DB Killer is inside the exhaust can and also fit the high flow air filter, just checking also that there is no air leaks around the engine manifolds (spray carb cleaner on them)
Ride for a little bit , check your plugs. Take pics.
Ride again after cleaning the plugs and see the colours again.
Show us we can then access how lean or rich the bike is , sometimes lifting the slide needle one notch away from the carb bowls actually helps the midrage and enriches the bike a little more.
Wish i did a tutorial for it! (like i did for the 125cc here but principle is the same on 650cc)2. That means the starter motor should not be jammed ? – Take it off and see if it whines freely when connected to the batter directly away from the bike.
If the starter motor is OK, then consider having a quick look at the flywheel sprocket (open the casing after draining the oil first) and see if the teeth behind the flywheel have any missing , i really hope not . I also don’t expect the “sprag clutch” that sits between the flywheel and sprocket to have any issues
I mention this because it does happen on rare occassion the starter sprocket behind the flywheel and its mini clutch to jam.
If all looks good, then it means the battery is too weak (cells inside caused voltage to drop fast) or just simply too old or too small (must be size 14BS factory size battery)
Or easy option, replace the solenoid relay , it is usually tht 90% of the time. Common part to replace on any brand big cc bike.
3. Take a picture of the mystery object 😉 and show us
Howdy Ken!,
- What size jets are on the bike currently or are you the only owner ? (untouched original) , but either way advise us as to what size jets are on it mains and pilots
- When you press start, does the bike make any sound/buzzes ?
or do any of the lights on dash or headlight go dimm (even slightest) ? - The horn is activated directly by the switch gear and the switch gear sends the wires to the back of the bike so that it shares the same fuse as other electrics (the main 15A fuse).
You can put a 12v meter there and see if you get any volt readings when you press the beep button on the switch gear ? - You may email me if interested but we do have a carb gasket rebuilt kit on the /shop/ section of the site.
Hello,
Its a nice idea but the 650 will twist the frame even if its reinforced a little, the Hyosung GT125/250 frame is even a little weaker than the original GS500 Suzuki frame, however Korea had no intention of putting the 650 in the frame production wise , so the 650 has its own frame for good reason.
Also they did “try” to put a 600cc (600!) concept engine they made in the GS500 frame, but decided it wasn’t good long term. Hence the GS500 was modified with a slight downgrade to just deal with 125 and 250cc , it’s more than enough for it.
Hey, i have got your private message , so i will see what i can do for you
It just sounds like a bit more TLC is needed being a new bike and a garage didn’t do a lot or took shortcuts , but i will wait for your next reply soon.
Never again lol. Zigger , just got lucky! – Im happy for you. Now get your gal ready for the spring 2022 coming soon 🙂 & happy riding for time being.
Hi all I bought diaphragms from the shop on this site for a gv125 etc etc . My current diaphragms in the bike are flat at bottom where the needle pokes through. And the ones I bought are alittle cupped. Which means they are for 250cc !?. Can i still use them in my 125 ?
Correct, absoulutely fine to use. ❤ Curved is better than flat!
The flat ones are more restrictive, so the ones you get even though meant for 250cc just means the 125 has an easier time lifting them or air flows through them in a less restrictive manner.
Try them out 😉 Let us know if you need further help.
I have not checked valve clearance. I was really hoping to solve this without having to really crack open the block.. I somewhere between novice and amateur.
You can open the valve covers when bike is cold overnight, and see if there is any clearance on each valve head.
It’s like i will spin the crank few times to get to F (front) mark on flywheel then quickly check clearances , repeat again for R (rear mark) on flywheel.
You can still consult the service manual if the clearances are not in spec, it has the explanations on how to set them up right.
Good tip Simon!
Hey,
Good that you changed the ECU, means you have a backup copy as these things are not always easy to get hold off.Have you done any ECU Code Retrival from the service manual (it’s in this forum) , these will display a code on the dash to tell us which part is being funny (since being an efi bike has many sensors on it)
It may seem like nothing but have you also ridden the bike with half a tank full and 2 big bottles of Petrol Cleaner (such as WYNNS EXTREME GOLD PETROL CLEANER) , ride the bike a little bit until the fuel level gets low. It is extreme to use 2 bottles but we want to see what happens when the fuel system cleaner is running through all fuel parts if it helps anything at all ?
Like i said, it may be nothing but taking small steps can *sometimes* help the bike get itself together. And use E5 fuel only where possible!
