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Just fixed combustion problem changing the pistons. put the bike compketely back together tonight start her up and now any movement on the throttle and she dies. rebuilt the carbs while they were out but did not adjust anything.

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Check vac. Reading. Am thinking you will show very low vac. Check yr crank to cam timeing i bet yr out of time

Posted on Nov 17, 2013

Testimonial: "Timing is all good. With the new air filter on can not go over 1/4 throttle. Cleaned the carbs again. Blew them out with an air hose checked the floats everything is set back to factory settings. Move the thottle passed 1/4 and bike dies. Adjusted carbs to be richier and had same problem. Adjusted carbs to be leaner and same problem. Put carbs back at factory setting and started messing with air box. With air filter off and covering 3/4 of the air intake with piece of metal with a shirt acting as a filter bike runs great. Modified the air filter box with the piece of metal and the shirt taking the filter out of the equation. So my conclusion is that the air filter is allowing either too much or too little air in. Dont know how to adjust that so it is modified right now with a piece of metal and a shirt acting like the filter. Bike rides great with the modified filter just dont want to continue using it for too long. Dont want to cause harm to the bike. Any help or ideas is greatly appreciated."


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Posted on Jan 02, 2017

  • 48 Answers

SOURCE: will only run with full choke and absolutely no throttle.

Carbs gummed up. Need a serious cleaning or a full ruubers replacement/rebuild kit. Gas turns to gummy when left stting in the fuel bowls.

Use a couple of cans of Sea Foam.. best stuff in the world.

Posted on Mar 20, 2009

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SOURCE: timing chain 110 hymoto pit bike

Put the piston at TDC (Top Dead Center) by lining up the timing marks on the flywheel and stator. Put the cylinder head back together with the cam installed so the high points of the cam lobes are pointing kind of downward. Pull the cam chain taught on the front side of the engine. Put the chain on the cam gear such that, when bolted to the cam, the index mark or marks are in the proper position.

The proper position depends on what markings are on the cam. Some bikes have a single mark; an arrow, a straight line or an "O". The mark should line up with the center-line of the crankshaft. If the cam has two marks opposite each other, the lines should be parallel with the gasket surface. You will need to rotate the unbolted cam left or right just a bit in order to match up the bolt holes to the gear holes.

Can I get a “very helpful” rating on this answer?


Posted on Aug 20, 2009

  • 296 Answers

SOURCE: my gs500f is back firing through the CARB. the

Lean mixtures burn very slowly, at times slowly enough to continue burning through the power and exhaust stroke, causing a backfire when the intake valve opens, and that flame gets a shot at the new mixture charge.

In normal operation, as the engine slows, the fuel delivery from the main circuit falls off, and the idle circuit is supposed to take over. If the idle circuit flows insufficiently, that becomes a transition to fuel starvation.

You can try pointing an unlit propane torch into the inlet air, and see if you can get closer to an idle while supplying a supplementary fuel source. You will need to do this in a way that gets propane to both carburetor inlets, maybe rigging a Y with vacuum hoses and electrical tape...

This started with work on the carburetors, so the fuel system would be the most suspect. That, and the fact that it will run at higher RPM would seem to rule out fuel delivery.

I was looking around at photos while developing this answer (needed to know whether this was a twin or a 4-cylinder), and one resource said the idle speed should be 1,200. I don't know if that's right, but maybe 1,000 RPM is too slow for this motor to keep it together. (I do doubt that, though.)

When I wrote that last sentence, I started to second guess myself, thinking "What if the fuel shutoff(s) is/are vacuum operated, and as the bike approaches idle there is insufficient vacuum to hold it/them open?" But the I rejected that, because there is even less vacuum at cranking speeds, yet the bike starts.

Posted on Jun 26, 2010

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I got a 1996 polaris xplorer 300 4x4 2 stroke. bike shutt off wouldnt start.some how fuel got in to the head .drained fuel out,have good comprestion still what do i do next

fuel can get into the head because the needle and seat if the carby is stuck open
the mixture ( in this fuel) is sucked into the crankcase during the up stroke of the piston then bypassed into the combustion chamber when the piston reaches a point on the down stroke
ONe fix is to shut of the fuel , fix the carby open the throttle wide , remove the plug and spin the engine over to remove all the fuel out of the crankcase
IT is effect very flooded now

May 26, 2016 | ATVs

1 Answer

2011 Honda CBF Stunner has blue smoke coming out of exhaust

Hi, Bibek your instrument gauges and lights can alert you to most electrical and engine issues they can not warn you about failed engine gaskets or seals so your engine has to resort to old fashion alert methods of colored "SMOKE SIGNALS" here is a breakdown of their meaning:
1. COLORLESS OR SLIGHTLY BLUE SMOKE on start-up means your air/fuel mixture is at the right composition and everything is well burnt in your combustion chamber.
2. BLUE SMOKE on startup is usually caused by failed valve seals dripping oil into the combustion chamber when the engine is not running.
3. YELLOW OR BROWNISH SMOKE at start-up means your air/fuel mixture is too lean. Too lean means that there is low fuel but high air mixture in your combustion chamber.
4. WHITE SMOKE on startup may be caused by a blown head gasket allowing coolant to enter the combustion chamber and may start dripping out of the exhaust pipes or mufflers. Smoke while riding is usually caused by worn out or damaged valves, seals, guides, pistons, rings, or cylinder walls.
5. BLACK SMOKE on startup is usually caused by too much fuel in the combustion chamber this can be due to air/fuel mixture adjustment too rich, accelerator pump improperly adjusted, faulty choke/enrichner or not in the off position, air filter dirty and clogged, faulty carburetor float needle and seat, pilot jet too large, fuel injectors leaking, smoke while riding is usually caused by the main jet being too large or a damaged carburetor.
It should be noted that aggressive or abnormal throttle operation will cause these conditions to manifest themselves exponentially.
For more information about your issue and valuable "FREE" downloads that you will need for viewing or printing please click on the links below. Good luck and have a nice day.
How to Fix Blue Smoke From Exhaust in Under 1 Hour
Blue Smoke Problem Wheeler Dealers
Honda Cbf 125 Service Manual
Honda CB Owners Manuals

Btw, I’m available to help over the phone in case u need at

Oct 22, 2013 | 2011 Honda CBF Stunner

1 Answer

Virago blowing out through air filter

Will, let me tell you the "Old school" way to fix this.(1) Remove all of the spark plugs. (2) Disconnect the fuel lines. (3) Pour light weight oil directly into the heads.(I know, sounds weird) (4) Crank Crank Crank Crank. Until the engine turns smoothly. If the valves were stuck, this should cure it! (5) Blow the oil out by the compression of the engine cranking. (6) Pour alcalhol into the cylindars to clean the oil out of the top of the pistons.(Starting fluid also works well) (7) Again, Blow it out using the compression of the engine. (8) Put everything back together and fire it up! NOTE!!!! Any time you know you are going to store anything with an internal combustion engine, treat the engine in the same way, by pouring oil into, and onto the pistons directly. This prevents seize ups, and helps to preserve oil seals. ^^

Jan 11, 2013 | 1994 Yamaha XV 535 Virago DX

1 Answer

Hello - I have a 2004 kawasaki 1500 vulcan nomad fi. I was first wondering how to stop the pining I get when ever I try to use more then 3/4 throttle and second I just installed a cobra exaust system

Pinging, or pinking as it tends to be called over here, is caused by detonation where for various reasons the fuel charge in the cylinder, instead of starting to burn at the spark plug with the flame front spreading smoothly across the combustion chamber, begins to burn in more than one place and the pressure rises too quickly mostly causing the audible pinging. It doesn't do the engine any good at all and has been known to melt spark plugs and pistons and it isn't always audible...

Low grade fuel is one typical cause. Using a fuel with a lower octane rating than recommended is one reason for pinging.
Sometimes an engine will retain carbon in the combustion chambers instead of getting rid of it. I don't know what causes one engine to rid itself of surplus carbon and others to retain it but carbon build up makes the combustion chambers smaller and increases the compression ratio and pressure, theoretically requiring higher octane fuel.

Carbon in the combustion chamber could be causing a "hot spot" that in turn is causing the second flame front or even igniting the fuel before the spark plug fires.
The wrong grade of spark plug can be a contributory factor and it is possible your engine should have a colder grade of spark plug.

Ignition timing that is too advanced causes the pressure to be too high.

Your new exhaust system could have less back pressure than the original and this would tend to change the engine characteristics, particularly the fuelling that could now be a little on the weak or lean side which burns hotter and could be contributing to the pinging and also exhaust popping on deceleration (as does ill-fitting exhaust joints).

Fiddling around with the throttle position sensor would be unlikely to provide a complete and permanent cure, I feel. I once had brought to me an engine that pinged almost constantly when our fuel became unleaded. At first retarding the ignition timing worked but over a few months it had to be retarded more and more until the performance was terrible. After removing the cylinder head everything looked normal though the piston tops and combustion chambers looked strangely black but nothing could be scraped away to leave shiny metal.
Shiny metal was achieved after using a small chisel and a light hammer to remove a substantial layer of the hardest carbon I have ever encountered. The engine then ran normally with standard ignition timing.

Mar 05, 2017 | kawasaki Motorcycles

1 Answer

Engine will not turn over

Start with backwheel, do visual check of disk pads, are they stuck to disk?. If yes, try operate foot brake and see if piston moves to press pads and releases. If not, disassemble caliper from disk, remove brake pads, clean exposed area around pistons using WD-40 spray, use clean cloth to wipe clean piston, push piston in using C-clamps until flat with cylinder, watch brake oil servoir not to over flow when pushing pistons in, stick both pads into caliper, push foot brake until it presses both pads.snug, remove pads, push piston back in again. Fit caliper and pads back onto bike, operate foot brake, check brake operations.
Use a 200-320 grit fine sandpaper, clean your disk surface, wipe with clean cloth so no rust dust sticks to disk. Clean pad surface with petrol, wash away any grimes and oils.
Using your hand you should be able now to turn freely the back wheel now..
Squirt about 5-10cc light oil into combustion chambers, ensure oil soaks onto piston rings, put in high gear and try combustion pistons to complete emptying-intake-exhaust-fitring cycle at least twice.
Do oil change oil with fresh new oil, ensure as much as possible old oil are drained out, change filter.
Clean out old fuel from tank + fuel bowl gunks, make sure all needles and float bowl are clean
While having sparkplugs out, spray into combustion chambers reasonable amount of starter spray fuid and put plugs and starter motor into place.
Now if you have kickstart try use it for a couple of turn else just use your electric starter motor, the motor should strat running. Keep it running for abouot 10-15 minutes before doing any riding ensuring oil have circulated properly.
Let me know if any other problem creeps-up.

Apr 14, 2010 | 2002 Suzuki GSF 600 S Bandit

1 Answer

Timing chain 110 hymoto pit bike

you have to put the piston at the top and the sprocket and crank at the bottom hope this helped

Aug 19, 2009 | Pit SSR 110CC Pro Beginner Bike

1 Answer

Yamaha dt 200 won't rev off idle

You should measure the combustion ratio.Maybe piston rings failed.

Jun 01, 2009 | 2005 Yamaha Xv 250 Virago S

1 Answer

Timing Adjustment issues!

If the bike runs then Top Dead Center (TDC) is not an issue. But to check piston stroke position, Remove the valve cap cover on the intake of the front cylinder. Remove both the spark plugs. Rotate the crank shaft untill the rocker arm starts to move. The piston is now starting down on the intake stroke. Rotate the crank further and the rocker arm moves in the opposite direction. The piston is now going upward on the compression stroke. Look at the marks on the flywheel. Rotate the crank untill the TDC mark lines up with the timing index mark. The front piston is now at TDC.

If your model has carbs then the backfire fix requires you to syncronize and balance the carbs.
Remove the air filter and rubber fittings to allow you to see into the throat of both carbs. You may need a mirror to see inside. You need to be able to see the slides go up and down when you twist the throttle. Now turn the fitting where the cable goes into each carb such that there is just a bit of slack in the cable, 1/16" is plenty. Lock ONE of the cable adjusters down tight. All further adjustments will be made on the other carb.

With the motor turned off twist the throttle very slowly while looking at the slides. Both slides need to begin lifting at the exact same moment. If the slides don't raise at the exact same time then slowly twist the throttle until the locked adjuster slide just barely starts to move. Hold the throttle still and turn the adjuster on the other carb so that the slide on that carb just barely starts to move also. Now recheck the slide movement timing. Do this process until the slides on both carbs begin to raise at the EXACT same moment. Lock down the loose adjuster and re-check the slides.

Turn the throttle screw on the LEFT carb one half turn inward. Now start the engine and get it warmed up. With the engine running, remove the RIGHT spark plug wire. Adjust the idle speed on the left carb to the point where the engine just can't quite stay running and dies. Now put the loose spark plug wire back into place.

Now turn the throttle screw on the RIGHT carb one half turn inward. Restart and rev the engine. Next, remove the LEFT spark plug wire. Adjust the idle speed on the right carb to the point where the engine just can't quite stay running and dies. Now put the loose spark plug wire back into place.

Turn the idle screw on each carb EXACTLY ONE QUARTER turn outward and restart the engine. The engine will be probably be idling very fast. Adjust both the idle screws equally from this point to get to the desired idle speed. Congratulations, you have just balanced and synchronized your carbs.

Please rate this solution. Thanks sgtswampdonk!

Apr 02, 2009 | 1999 kawasaki VN 800 Vulcan Classic

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