Wit's end

[jwr3k]

Holy Christ. it's been a s**tty 3 weeks. This is the longest time in a couple years that I haven't had my bike running. I feel like I've gone over everything, even replaced a few things, but to no avail. I checked for clogs in the feul line, removed and cleaned the carburetor, and also checked that gas is getting into the bowl (it is). Also I replaced my cylinder body, and magneto coil, the crank seals are relatively new and still in great shape, replaced my piston rings. I tested the plug outside of the cylinder and it's seems to have a really good strong spark. But I still can't even get the motor to start at all. Before it died, it like kind a slowly lost power over a few days and hasn't ran since. earlier this year I replaced the entire clutch assembly too but it seems to work better than ever. So I'm kinda stuck. Could it be sparking really well, but maybe have bad timing from the CDI? Also there is a little bit of carbon buildup on the piston head but I don't feel like it's enough to cause any problems.

 

[Chainlube]

With the head off check your spark, see if the piston is up when it sparks. The mag could of broken the key and rotated around the crank.

 

[gary55]

With all those new parts it's possible you fixed the initial porblen, but created a new one in the process. possible places to look . First thing I would do is check all wiring and try it with the kill switch unplugged. What is the compression? you might have gotten a cylinder that is 2.780" (A type) for a 2.740 (B type) engine. This could drop the compression enough to not run. Like chainlube said when you replaced the magnet the woodruff key might have slipped out of place. Did you visually inspect the jet for obstruction?

 

[wan37]

Yes it could be timing check and see if the magnet is put on wrong way . It will spark like it’s working but it’s firing at wrong time. Just a shot

 

[jwr3k]

yeah, the magnet and woodruff key are indeed intact. I haven't pulled my head yet, but I removed the magnet and physically checked the key. The notch also points to 1 o'clock or so. Even so I tried the magnet the other way just because I hadn't tried that yet and nothing I had tried seemed to have worked. One thing is that when I got the new cylinder, it must've been a tiny bit (.04"?) shorter because my piston was hitting the head, perhaps I had a type A cylinder originally and got a type B accidentally. I had to throw on a couple head gaskets to give me enough clearance for the piston so the engine would be fully able to crank over, where can I find a cylinder that's tall enough? Everywhere that I've been looking seems like they don't specify type a or type b. Or perhaps it would be easier to get a new piston head with a higher hole so I wouldn't need the jenky extra head gasket BS. Also, I cleaned my jets with one of my finer guitar strings and also tested it with a different carb I had lying around, with no detectable difference in effect on changing the no start situation. FYI killswitch has long since been removed from the electrical system just to eliminate it as a potential problem.

Thanks guys

 

[Chainlube]

It's better to raise the cylinder with two base gaskets than the head.

 

[jwr3k]

Ok, well I do happen to have an extra base gasket, I'll try that after I pull my head and try a couple things, Also do I have to disconnect the CDI to test in order to test it all wired up? And how would I go about testing the CDI?

 

[Chainlube]

Ok, well I do happen to have an extra base gasket, I'll try that after I pull my head and try a couple things

You can check over the piston while you have to jug off, see if there is any broken rings or gouges.

 

[jwr3k]

You can check over the piston while you have to jug off, see if there is any broken rings or gouges.

That was actually the original reason for replacing the cylinder and piston rings - one of the rings had gone bad and there was this wierd lip that had been worn into the side of cylinder. After replacing those, compression seemed to increase

 

[jwr3k]

I do have a new piston head that is in much better shape and much cleaner than the one currently in the cylinder and I plan on installing that. Even though there is no discern able Asymmetry in the new piston head, it has an arrow pointing in one direction along the top. I assume that would point towards the exhaust? in the direction of flow? Also the new stator coil had a blue and red wire soldered on and a black wire with screw loop, I assume the black goes to one of the frame bolts, but then do I still wire black to black , blue to blue, ? I feel like it would have to involve the blue and the red wire