ignition timing retarded or just me?

[justin s]

i have a 78ke125 that will run good for the first 15 minutes, in all gears. Then it will start backfire and sputter to the point where it will not run. I suspect the ignition timing is a little off. I have cleaned the carbs thoroughly multiple times and I don't think that is the problem. I have tried to replace the ignition coil but that did not solve the problem. would the ignition timing being off affect the performance only after the bike has warmed up or wtf is going on. please no stupid answers

[G B]

Being that your bike is a1978, I am going to guess it has points and consensor. If so, I would suspect that the condensor is going bad. Probably cost you about $15, and unfortunately you will also need to buy (or borrow) a flywheel puller. The puller for that machine is not expensive, probably another $10. Of course, once you are in there might just as well replace the points while you are at it another $15.

EDIT: If you want to know how to set the timing drop me a note.

[awesomefb]

Your question is funny, Hahaha !! But the answer is you, if you can't figure it out. Sorry.

[Don E]

Justin,Gap the points to .014 thousandths make sure the condensor is on tight. Other possible problems could be, broken ignition source wire where it comes out of the engine side case,Check air screw on carb for proper turns out,Rectifier diode may be failing ,Make sure battery is being properly charged,check with engine running.It should read over what the battery voltage is.On those bikes the point gap was real critical.

[1crazypj]

Try the fuel tank and carb vents, they may be blocked. Possibly rust in the fuel tap (petcock) If it starts up when warm/hot after a couple of minutes 'rest' its a more likely culprit