Kazuma 50 carb woes......
 

Been working on my sons Kazuma 50 for a while now. It does not start when it is cold. It doesn't even try to fire. Won't even hit on ether. If I pull start him, I can get it to run after pulling him for a bit and then once it gets good and warmed up, it starts right up. But you let it set for 30 minutes, and then you have to pull start it again. I have cleaned the carb thoroughly, I even bought a new carb, and tried a new plug. Still nothing. I have read a few posts about the intake manifold getting a crack in it. How obvious would that be? Could that be causing my problems? Another symptom is after I do get it started, before it gets good and warmed up, it "cuts out" really bad. Kind of hard to describe, but it just stumbles all over itself and you have to run it at full throttle until it gets good and warmed up. Anybody got any thoughts?

Thanks,

Jon

Kazuma 50 carb woes......
 

Squirt some oil in the spark plug hole when it is cold and try to start it. If it starts, you need a set of rings. I don't think it has anything to do with your carb. The problem with the 50 cc bikes is the air cleaner needs to be cleaned and oiled every 10 hours. It's small, dries out and sucks dust in the motor thus wearing out the rings and loosing compression.

Kazuma 50 carb woes......
 

Start with the simple things first and eliminate possibilities as you go. Remove the fuel line going into the carb and turn on the gas - fuel coming out of the tank? Is the float set properly in the carb - with the float bowl removed, turn the carb upside down - the float should be level or parallel with the bottom of the carb housing. Remove the spark plug - what does it look like when it is removed , is the gap set properly, what color is the electrode area of the plug brownish grey or is it white. A white or a light color will indicate a lean mixture or air leak. What is the idle mixture screw set at? Try turning it all the way in until it stops (gently) then back it out one and a half turns for a baseline. Are you getting a lot of blue smoke when it is running? That would indicate rings. Take the intake manifold right off the engine and inspect it for a crack. A simple way to test for an air leak with the manifold on though is to get the engine running and mist (light spray) carburator cleaner at the intake manifold, again light spray don't drown it. If the rpm increases you have an air leak somewhere (or cracked intake). Obviously be very careful where you spray the carb cleaner not on exhaust or on rubber hoses. I don't know what your level is so forgive me if I am stating things you have already done. Let us know how you make out.

Kazuma 50 carb woes......
 

One more thing, have you done a compression test? if you don't have a tester the oil trick described above works well. You can also remove the spark plug and stick your thumb over the hole. You should be able to feel the suction and pressurizing of the combustion chamber.

Kazuma 50 carb woes......
 

Thanks for the tips guys.. I have tried most of your suggestions. Trying 2 carbs, pretty much eliminates a carb problem. I have tried the carb cleaner trick to try and locate any leaks, and none showed up, but I still may remove the intake manifold. Rings had crossed my mind, and I admit, I have not been real good about maintenance on the air cleaner. It does not smoke at all when it is running, but I will still do the compression test. I have never heard of the squirt of oil trick, how much oil are you talking about? I will give that a try too.

Thanks,

Jon

Kazuma 50 carb woes......
 

Are you still running the stock spark plug?

Kazuma 50 carb woes......
 

THe squirt of oil works. I have a Kazuma 50 and it had the same problem... it wouldn't start when it was cold but once you got it started it would run fine(i would get it started by putting a heat gun on the cylinder for a few mins to warm it up). A warm engine is tighter because the piston expands in the heat thus giving it more compression. It's not only the rings that take a beating when you get sand in it. The whole upper end takes a beating. You should also check out all the other suggestions stated above. I solved my problem by purchasing a whole new motor on ebay for $225 because the parts would almost cost you the same and swaping the engine is half the work.

Kazuma 50 carb woes......
 

I have switched to an NGK plug

Jon

Kazuma 50 carb woes......
 

This sounds like the valves just need to be adjusted, we have alot of people wanting rings & pistons & such for the 50cc's & I tell them to just go adjust the valves & never hear from them again.... set the at .004 intake & exhaust.... my guess is this will fix your cold start & running problem.

Kazuma 50 carb woes......
 

Excellent idea spliffy, I assumed it was a 2 stroke.