Why won't my motorcycle idle?

Question

I have a 78 Kawasaki KE125 that I can get kick started but it will not idle. I start it with choke all the way in and when I give it gas it cuts off immediately. When I start it and don't give it gas it slowly sputters out. I have recently cleaned the carbs. I have checked the hose that connects from the petcock to the carburetor and the fuel gets through. I have tried adjusting the idle knob but I do not have a manual yet and don't know the exact setting. What else should I be checking?

Also when it cuts off the kick starter pops up. What is this a sign of?

Answer 1

This model has a rotary valve intake so the carb is mounted on the right side of the engine for those of you who are interested in such things. The idle adjuster is on the front of the engine on later models and on the top of the carb on early models. For the screw on the front you just turn it clockwise to raise the idle. For the early models you turn the rubber post counter-clockwise to raise the idle. The low speed air/fuel screw is in the bore of the carb. About 1 1/2 turns out should be a good start.

You have a fuel / air problem. Check the flange where the carb bolts to the rotary valve cover. If it isn't sealed properly it will draw in air and lean out the mixture. Check the rotary valve. Look in the hole with a flashlight and see if the ends are broken off or damaged. Clean your entire fuel system starting with the fuel tank and petcock. Remove all the jets in the carb and verify they are clean. The pilot jet is very small on this model and if plugged it will do exactly as you describe. A low float level will also cause most of the problems you describe.

The kickstart thing is normal. When the bike dies it may turn the motor backwards which caused the kickstart gear to engage.

Answer 2

A KE only has 1 carb. It's very important when cleaning the carb to get all of the little nooks and crannies. Especially the idle jet and main jet. It's really hard to get these good and clean. Then after you clean them out they can get plugged quickly (seconds) if there's any crud in the gas or tank. Also check for air leaks in the boot from carb to motor, Reeds may be bad. Get it running like it sits before you adjust too much. It shouldn't take more than about 1.5 hours to get the carb real clean and check the reeds.

Answer 3

pull the petcock out of the tank.......you might find your problem because there is a screen inside. try this, turn the gas on for about a minute or two.......if it runs a little longer than you know there is a fuel problem before the carb......if it doesnt change a thing then you have to recheck the carb(S). mainly the idle jet that goes down in the float bowl

Answer 4

May need a top end rebuild (cylinder bore, piston & rings).
Do a compression test.
OR
Remove the exhaust pipe and look in the exhaust port with a flash light and mirror.
If you see any scoring of the piston and cylinder wall, or dis-coloration below the rings, the top end will need to be rebuilt.
Carburetors don't go out of adjustment.
They just need re-adjusting when the engine wares out.
Check the reed valves.
Remove the reed block and hold it up to the light.
You shouldn't be able to see through the sealing surfaces and they should show no signs of ware or damage.

Answer 5

Wow, lot of ideas, but mine is a little cheaper. Nine times out of ten a bike that all of a sudden will not idle has a leak in the rubber collar that attaches the carb to the cylinder. Get a can of wd-40 and get it started and get the rpm to where it won't die, then spray around the back of the carb, it should die if there is a leak.

Answer 6

i think of ur motorcycle engine have an uneven firing order. yet i'm no longer very sparkling. i counsel u to get on a internet site called bikerkiss to ask for help. there are a number of motorcycle professionals there.

Answer 7

It sounds like you have the right idea, play with the idle adjuster, if that doesnt resolve it, check the spark plugs and wires and the other electrical.