♠️ M77
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Sorry i delayed, to answer you, i would start by fixing the bike using the suggestions mentioned in my past comments.
The pump sits at the rear of the frame, it doesn’t touch the engine. Also the bike in your profile image suggests that it’s naked enough to allow enough air flow all over the bike anyways.
Replacing the pump is usually the last resort, it tends to last a long while when its well maintained.
You should get Motul Factory Line coolant for bikes. Its mixed already and is better at doing its job over cheaper coolant bottles. I can vouch it myself having used it on smaller liquid cooled bikes in the past.
As its a public forum. You should PM me concerning security matters on the bike or a garage can actually do it with discretion in mind.
Usually the bog downs or cutting away means electrical issue or fuel delivery system.
Lets deal with fuel first.
- Go to the rear pump. Open its metal shield cover. You will see a glass window inside. Get CARB CLEANER. Spray inside through the GOLD PORTS only. Do not spray inside the GREY port. Now you must see the particles get cleaned out. remove the window (watch the gasket!). Clean the window too. Dont remove any moving parts of pump. Clean up and close the pump tight. Fit it back on the bike.
- Change the fuel filter.
- Clean the carbs…. see below
Get compressed air. Open the carb. Clean HARD the Pilot Jets. MAIN jets. And also the *enrichment tube* that is permanent on the carb.
Then clean every *hole* you see inside the carb hard so all the particles go out. It is crucial. CARB CLEANER (Liquid) helps also but it is better to use compressed air to blast every tiny hole though!
Put your carb upside down on a table (floats facing the sky). Get a ruler. Start from 0mm on the FLAT EDGE of the carb base (where bowl gasket sits on) . then make sure all 4 floats are 7mm height. not less. not more. this float controls how much fuel you get from idle to top gear. You dont want the carb starving or overfueling. 7mm precisely at the top of the float on your ruler. or adjust the float metal tangs a little bit! Then recheck.
Floats all good?. last mission is to clean the diaphragms at the top (black slides) and search *Slide Mod* on this forum on how to improve the slide needles.
Now the carb should be really clean and prepared. before fitting on the bike…. do the following below…
Go to intake manifolds.
- Be very gentle. It is very very very hard to get new ones (not made anymore).
- Remove intake manifolds
- Check for cracks / damage (vacuum leak!)
- Check Oring isnt cracked (very important for air leaks too)
- Clean them. And grease the ORings.
- Fit them back on the back.
- Use fresh bolts and washer and tighten (be gentle!)
We have cleaned the carb. we have checked the intake manifolds. put the carbs back. put the airbox back too. Be gentle as carb intake manifolds will crack open if there is too much weight or pressure on them.
Connect the fuel pump. get fresh fuel lines. get fresh vacuum lines and clamp all lines tight to stop vacuum leaks.
Start your bike. Get CARB CLEANER. spray the intake manifolds while she is on IDLE. if revs go up^ = you still have a leak. fix that area. if you spray rear manifold and revs go up , investigate rear intake system there as an example.
Last mission go to the TANK.
- If you have a vacuum tap on the tank. start your bike. rev up multiple times. You should see fuel gushing down the filter. That means the tap is squirting fuel in to the filter.
- After a short ride, fuel filter should be FULL if it is a small one.
- If you have a manual ON/OFF tap on the left side of your bike frame ==> Go under the tap. Open it. Clean the dirt traps inside.
- If you have a ON/OFF tap that also means your tank has 2 pipes that go down to the ON/OFF tap. On your tank => remove the spigots that side inside the 2 holes. ((From tank rust or dirt that may prevent fuel coming out of the tank to feed your bike))
I hope i have made sense. Try everything i said above. And let us know if there is improvement even if it is small or better. It will respond better when you make progress.
Before we address anything else lets attack 1 major thing so they are out the way.
Carb unit
- Are the floats 7mm height. This is 1st as its a big deal. Less than 7 or more than 7 the bike wont ride properly even if carb was clean. so that means carb is on the table with the floats facing the ceiling. Leave them for a second. Get a ruler. The highest height for all 4 black floats should be 7mm mark on ruler starting from 0mm on the FLAT EDGE of the carb body where bowl gasket sits on.
- Sorted? next take out the floats. Take out the fuel valve and MESH thats down there. Clear the particles.
- Put all valves & mesh back. Floats back. Double check it is 7mm height or adjust its hook tangs (a LITTLE bit!)
- Take out Pilot Jets. look at the sky through them. You should see a clear hole or clean them hard. its very easy to clog em.
- Ofcourse clean the main jets and its tube holder.
- At since the jets are out. Get compressed air and blow every single hole thats on the carb. EVERY HOLE. including the TALL JET that is permanent on the bike. (Aka. Enrichment Tube).
- Close the bottom of the carb.
- Open the top. Take out the diaphragms. Clean with a dry cloth. Check NEEDLE HAS MOVEMENT (it is spring loaded). The needle bounces up n down by about 2-4mm. Search *Slide Mod* on this site for more tips on adjusting it.
- Clean the piston walls smooth.
- Check springs arent tired.
- Close the carb.
Report back to see if she is better at all?
If you head over to the manuals section of this forum , get any CC hyosung service manual because the principle is the same. It usually details how to remove / install cam tensioners.
Then because you have a 125cc vtwin. Use only 125cc/250cc vtwin service manuals (Carby 12/250 and 250 EFi are the same process for installing cams , tensioners.
We don’t know what size your tensioner or year of your engine. You have a tensioner that has a rubber cap behind it or a HEX screw behind it ?
Either way, a tensioner is usually released by — > removing the cap/fat-hex-bolt behind it –> a watchmaker screwdriver unwinds it slowly till it stops by itself, don’t force it. –> then it comes out by detaching it off the engine heads. Most modern bikes are this way (most brands)
Hope this info was helpful, shame about the situation , that’s not a good day. I hope you get it sorted, summer is fast going away now!
Can it bump start ? -> ride a bit after its warm around the street -> try electric start again.
Welcome fella.
The RT is a fun little bike for some small trail riding if you get off the tarmac 😉
Enjoy it while the sun is still hot 😉
What is the other hole on the tank? The one that Tank #1 has a hose attached to? I’m not sure that hose is supposed to be like that.That’s the overflow to the ground
So basically, when you press “start” does the orange LCD go dark at all ? or headlights go dimm ?
If they went dimm -> battery to weak to spin the pistons (not voltage always, but sometimes the cells are too old) but you said the battery is new. I hope its 14BS size , as that’s what OEM says to use. Smaller than 14BS isn’t ideal.
If the battery was brand new and size 14BS (ideally) , but you don’t hear anything , not even a click, the ORANGE LCD doesn’t go dark at all —> Check solenoid relay (common) (it’s that’s strange rubber ball with wires sticking out and sits above battery)
If the solenoid was brand spanking new –> Then open the right hand switch gear , clean any rusty contacts with contact cleaner (halfords) -> Apply ACF50 to the gold pins inside (halfords again)
If the right switch gear looks good. Drop the oil cooler at the front of the bike so it sits lower, then look for a BLACK PLUG , that’s for your right switch gear. Don’t faint when you see it covered in water and the pins have gone green, you know what to do on this part too. I would also cover it in LOTS of tape to waterproof all the plugs that are down there.
If you can’t see the black plug easily , then you may have to drop fairings and gentley loosen the airbox that’s sitting on the carb. Please, please, please, tighten the airbox hard when you are done and do not apply pressure on the rubber intake manifolds because they are VERY difficult to get (not made anymore forever)
I hope this info helps to get you started but let us know how you get on!
The hyosung twins shake a little , and especially with aftermarket exhaust, they roar a lot sometimes 😉 (depends which brand etc)
I have seen people try to use softer cushion pads under seat, suspension adjustment at rear and also better fork oil at the front , then we have softer hand grips for the hands
http://www.ebay.co.uk/usr/evocrest
If you see it. PM me directly here so ill add it to your shipment if the weight isnt too much.
Hey,
It is sold as a complete unit usually.I believe i may have one or a pair but you will see it on my ebay.
From the service manuals uploaded to the site (650 has the same process generally); check these:
– Regulator output from idle to 5k revs
– Stator output from idle to about 5k revs ish.The regulators is likely the main problem. Inadequate charging (& generally DC electric supply to the bike)
Hence commonly to change these units to something better like Shingden. Some wire splicing may be warranted. Electrosport USA is another. I wouldnt use any Suzuki OEM regs or Hyosung regs anyway.
Good luck!
Thanks Marcel, I have read both those very informative tutorials you have done, so it looks like the carb’s are coming out (as I thought and best practice) can you recommend where I can get the two main jets I need!
You can PM me as i have some ebc ones stocked. should be cheap airmail also.
Hey,
it is not ideal to work on the carb while it is resting on the manifolds because the rubber is very easy to crack and it is very hard to order new ones since Hyosung stopped making them (discontinued). Even the engine can be lowered down to have more room to remove the airbox.
I would rather hold the carb very tight with my hands while forcing the airbox out of the bike. strange design yes it is but thats Korea lol
Carb jetting = there is a [Tutorial] already on the forum , check it out. for GV125 i would use 90 front mains and 92.5 rear mains. Thats more than enough even for summer heat. you dont want the bike too rich it will start bogging down unless you have powerful electrics , freeflowing leovince pipes.
92.5Front and 95 rear would be extreme but a limit! thats a 250cc bike jetting!
The pilot jets = never changed. And also never mess with the mixture screws too, it would be the abyss if you do hence its usually discouraged by the OEM maker too.
Standard CR8E or Laser NGK is more than enough. Hyosungs like the size 8 plugs. they run weird with others. Denso is not good for hyosungs either.
You are better off by improving the oil cooler system to a 250cc one, ngk laser plug, better ngk caps as they handle heat better, coils, slightly richer carb.
Also check (Slide Mod) on this forum which helps the bike speed up around 4k-8k revs (mid range tune)
Hope this info helps, lets see how you do 🙂
I would not advise manual tensioners in my opinion, to put in short:
- Race teams dont mind, they do engine rebuilds or have access to the motor all the time
- Not really for street use
- if the chain starts to wear down (it always does), the tensioner “MUST” be adjusted frequently or always checked the tension is good.
- if the tensioner pushes too hard , the chain will go or cam parts will wear off much sooner
- if the tensioner pushes too loose, the cams will jump a tooth at high speed and possibly take out a piston , because if it skips timings, the valve will hit a piston.
- you have to stay on top of it , the more of a daily bike it becomes eg riding far miles to work every day, the more it needs attention (says so in manual)
You can PM me i may be able to supply you a new cam chain within the same week fast , i think its still there.
Automatic tensioners are ideal and they work, like every other bike brand out there, sometimes they make sounds causing us to change them almost immediately before they cause issuses to the engine, sometimes bad batches are made (rushed in production), some will survive for miles and miles.
Hyosung 125GTs & Rs have been through 3 tensioner designs , you didn’t say what year your engine is ? it has a big head or a small head tensioner behind the motor. (do you see a center bolt in the middle or do you see a rubber plug in middle etc…)
Hey,
Sounds more like the fuel pump needs attention as well as the Fuel Tap, we talking about the fuel delivery system starting to wane , the bike can’t be drinking from its carb then cut you off if the taps n pump are moving slow.
The usual check for vaccum being strong is to make sure the lines are good and recent, investigate the manifolds so they aint leaking any air either (spray carb cleaner there and see if revs change) .
For the carb, quick check that the float assembly is good , as the float assembly parts including valves under it control how much fuel comes in. You want the area unclogged also, while the carb is still open, you could aswell just have it go through a nice soak of carb cleaner and if possible use compressed air to really clean it out!
last not least, consider the fuel filter, if its dirty or you see particles = change it out right.
Lets see how you get on, good luck!
Michelin Pilot Road 2 , 3 , 4 = They are just too good. My fav brand and type to use on whatever sport bike i own , even naked. 🔥
2nd option for me that works is these = Bridgestone BT92 , BT23 , T30/31 sport touring. I’ve had BT92 , it’s probably my fav bridge tyre but it seems to be less common in UK now days!
Just dont buy cheap carcass rubber like maxxis , dunlops, avons – i really hate those tyres!
