TIMING problems,

[destroyn]

hello all, new to the forum and xs650s, I bought a basket case 77xs to build into a swing arm chopper, I had to make the wiring harness, as the bike pretty much came with engine frame front end and wheels, The problem i am having is the right cylinder is shooting flames thru the carb,

Motor has great compression on both cylinders,
carbs are freshly rebuilt,
pamco ignition system,
the plugs are firing good,
checked the coils,
plug boots,
valves are adjusted properly,
timing is set,
timing advance isnt binding,
back fire wont go away with any play of ignition plate,

left side runs great, no back fire, pipe gets good and warm, lots of pressure shooting out the pipe,

right side, back fires thru carb, combustion is happening early, so no warm pipe, no heavy pressure from the pipe, and is ruining my fun

if any one has any ideas , or things that ive missed, id realyy appreciate it, i feel i got the bases covered and should be sliding into home, but defintly not working out

thanks

 

[irristeve]

have a look at advance mechanism there is 2 ways it can go the disc with 2 groves that locate the avance weights has a line on it which line up with a line on the other bit(the bracket the weights swing on)hope this helps,my rephase witch has a pamco has to be 180 out on this mechanism wish I could explain why but I cant,but it runs great so dont care.Failing that get hold of pamco pete.

 

[pa23driver]

noticed you said carbs are freshly rebuilt - did you properly sync them? its amazing how poorly these engines run with the carbs even slightly out of sync

 

[pamcopete]

destroyn,

Well, the PAMCO fires the coil twice per revolution of the cam shaft, or once per revolution of the crank. It doesn't matter if it is 180 out on the cam shaft because this is a wasted spark system with one cylinder firing on the compression stroke and the other on the exhaust stroke.

If you are getting one cylinder to work, the the PAMCO is working, except for one possibility....a missing magnet, which would cause one cylinder to fire on the exhaust stroke only. So, take a close look at the PAMCO rotor and count the magnets. Should be 4, one in each hole.

Pete

 

[Grinder]

If you switch plugs and wires from side to side does the problem remain on the right?

 

[AndreXS]

got a 81 electric ignition kick-only bob. cuts out and will only start if kill switch is pressed and combustion occurs in the exhaust pipe. however if I turn it off it starts again, problem only occurs when engine cuts out?