Engine tries to fire just as you try to kick (start of stoke

[donte7430]

Unfortunately I am very inexperienced on Yamaha engines. Here is the scenerio:

Have a xs650 that was built for the David Mann Show in Ventura Ca. It took first place metric chopper. Problems started when we found out the "motor builder" totally screwed up. It supposedly was ready for electrical and good to go, not the case.

They didn't torque anything down missed proper gaskets (leaked like a sieve), so virtually no compression. The biggest screwup was the cam being installed 180 degrees out. I was able to address all the above problems.

I put a new pamco ignition in it, cleaned carb (has a single carb feeding a custom manifold) gas provided to it. I kicked it about 4 times and it fired up- but the idle was very high, ran for about 30 to 40 seconds and died (think it ran out of fuel, for testing I am using a IV type feed). Filled gas supply got it to fire again ran for maybe 45 second backfired and died.  When I try to kick it with ignition off it kicks through smoothly. As soon as ignition is on it seems to try to fire with barely any kick motion and feels like it locks up momentarily - kick starter moves another inch or so repeats locked feeling and sometime it spits fire out carb violently.

Any direction you guys can point me in will be greatly appreciated   

[grizld1]

The first thing to check is ignition timing. If you have the starter motor still in place (the Sawzall artist who "built" that mess probably got rid of the button and solenoid), you can bring a good battery to full charge, and use a pair of jumper cables to spin the motor. Ground the negative terminal to the frame with one cable, clip the other cable to the starter motor terminal, and touch the other end of that cable to the positive terminal. Do this with plugs in the caps but removed from the holes and grounded firmly on the motor. This will let you hit the timing marks with a strobe and find out where the retard mode timing is set without frying your ignition. If you have no starter, you can get a flash out of the timing light by following the same procedure (plugs out and grounded)and having a helper boot the motor. Just get close enough to fire and keep going, then finish with the strobe.

Once you have your idle timing dialed in, wind up the motor and check the advance. If you can't get the timing set in the idle range without overadvancing when rpm's are up, replace the timing unit.

[donte7430]

Thanks for info. Bike is kick only. That being said I pulled the advance arm plate off to check alignment of pin in cam. Found that pin had not only sheared but ripped the lip on the plate where it sits that in turn let it advance way past where it should( plate had turned nearly 45degrees from where it should be with correct alignment)

So I'll either replace that or maybe just get the new pan I elect advance. Either way have to correct the advance weight issue befor proceeding

[preston]

This advance system from pamcopete looks good to me, but i have not purchased one, yet.
Preston
*
NEW! Electronic advancer for the PAMCO Hall effect ignition!
by PamcoPete
Now you can eliminate that troublesome mechanical advancer and replace it with a reliable MCU* electronic advancer.
Precise lookup table for advance degrees / RPM
Automatic kill switch keeps coil off until starting
Eliminates advancer jiggle for a smoother engine and less vibration
Extremely low power consumption (220 microA)
Easy installation
Upgrade your existing PAMCO or combine with the new Hall Effect sensor

[fredintoon]

Jul 23, 2013 18:33:29 GMT -5 donte7430 said:

Thanks for info. Bike is kick only. That being said I pulled the advance arm plate off to check alignment of pin in cam. Found that pin had not only sheared but ripped the lip on the plate where it sits that in turn let it advance way past where it should( plate had turned nearly 45degrees from where it should be with correct alignment)

So I'll either replace that or maybe just get the new pan I elect advance. Either way have to correct the advance weight issue befor proceeding

Hi donte,
after the timing problem has been sorted, there's a trick to kickstarting.
It's about the only good way to kick a big single but it's reasonably effective on a vertical twin.
Put the bike in 2nd gear and pull it backwards until you feel the engine come up against compression.
Click the transmission back into neutral.
The engine now has the maximum available rotation to draw in a fuel charge and build up momentum before the ignition sparks.
Now kick.