Hey everybody. I need some help here. I just got my 'zilla all the way back together with the new piston and rings, bore, new gaskets, new reeds, new plug, cleaned carb....everything. The problem is it won't crank! The day I got it back together I kicked it and it started right off the bat. In fact I fired it up three times the day before yesterday and let it idle. Now it won't do squat! I've checked the coil, the carburetor, the plugs, the pickup coil and don't know what else to do. It is getting gas and it has a great spark! What's up? I've tried dragging it to start it and nothing. Every now and then it will backfire and that's about it. Has anyone had this sort of thing happen to them?

It sounds like a spark timing problem. Your quad could have great spark but, if it isn't at the correct place in the crank rotation, there will be no combustion. Take off the flywheel cover and check the situation. You could have a broken flywheel key (this often happens if the flywheel was not properly torqued on). Also, the stator plate underneath the flywheel may not be properly positioned (again do to improper installation). If you have good: spark; compression; and fuel ingestion then the spark timing is the most reasonable cause for the symptoms you have mentioned.

If i remember correctly, i think zillaman posted some help about this problem. I think it was something to do with the timing key breaking. this will stuff the timing of the spark. just check for the three basics, fuel, spark and compression (also check for a clear airbox! ive heard people leaving rags in there! hehe) and when they all check out, then it is usually a timing problem. a backfire is most definately a timing problem.

Is there an echo in here? Apparently they need to do something about the acoustics in this forum.

I had the exact same problem with my 87 zilla after the rebuild...pulled it all afternoon behind the car with an occasionnal back fire. Turns out the flywheel key sheared in half...put a new key in and fired right up. You must tourque that nut real tight. The key is there for timming only... it is not meant to drive the flywheel. The taper is what drives the flywheel. In the machine shop we drive some 3 inche drill bits with tapers alone.
hope this helps

87 zilla
87 quadsport

Yeap...definately an echo. Must be the rubber walls in this insane asylum

I can't say for sure but you may have a timing problem. I would check the flywheel key, it may be sheared..........[img]i/expressions/face-icon-small-wink.gif[/img]

It was a sheared key, I didn't get the nut tight enough. As I said in some earlier posts, I had a less than competent mechanic almost ruin my motor. In seperating the case halves, he beat on both ends of the crank and thus damaged the threads. I put the nut on anyway and damaged the threads in it, causing it to fail. Thanks a million for your prompt response to my problem.