'79 GS850 wont' start after top end rebuild

[wymple]

Make sure your timing reads correctly AFTER the cam chain tension is done. On many engines, tensioning the chain can roll the cam off perfect a tooth or two. The XS650 comes to mind. I'm betting on cam timing anyway, since your compressions are lousy everywhere. Also, make sure the throttle is wide open on the compression test. You can't compress air it's not getting.

[Tanerrx]

Thanks for the advice guys. I redid the timing and double checked all the marks and that is what got me to this point where the bike will run for a couple seconds before dying.

I'll give the flashlight in the spark plug holes a try.

Could anything electrical keep the bike from running? Seems like the only thing I haven't checked. It is obviously turning over with the electric and kick start. I thought the bike just ran off of the engine after that point but I feel like I've read before that a bad alternator could cause a bike to not run.

[Big T]

It needs a charged battery to run

If it starts on the electric start, I wouldn't worry about the electrical stuff

Is it running on all 4 cylinders?

[Tanerrx]

Is it running on all 4 cylinders?

How can I check this? I've done the compression tests and they are all reading around 50psi and 60psi but like I said I think my compression gauge might not be very good. Is there another test?

[Tanerrx]

So it seems like I'm not running on all cylinders. The bike will turn on and run consistently after letting it rest for a few seconds in between turning it on. I touched the exhaust pipes and 1 and 4 were hot, 3 was warm, and 2 was cold. What is happening here? Could it be a combination of low compression and fuel not getting into the carbs fast enough?