CoastsideXS650
Princeton Motor Works
Hi guys. I’m looking for some suggestions as to where to look for a intermittently firing right cylinder at idle.
The basics:
1980 xs650 motor with fresh bottom end rebuild, installed 700cc pistons and fresh top end (valves lapped not re-cut). Stock bs34 carbs and air boxes, black box ignition unit which works properly, dual output green monster coil.
The bike starts fine from cold. Runs very well when choke is on. Once warm the right cylinder drops off at idle speed and the whole thing runs on one cylinder.
I have checked the following and don’t seem to have anything wrong:
-swapped out carbs off perfectly running bike and no change in behavior.
-intake and exhaust have no leaks (carb cleaner spray check method)
-both plugs are firing (used inline spark plug light to check)
I haven’t checked the compression or done a leak down test. My instincts tell me it’s electrical of some kind.
Any ideas or suggestions out there from people? I’m getting pretty stumped and could use some help.
The basics:
1980 xs650 motor with fresh bottom end rebuild, installed 700cc pistons and fresh top end (valves lapped not re-cut). Stock bs34 carbs and air boxes, black box ignition unit which works properly, dual output green monster coil.
The bike starts fine from cold. Runs very well when choke is on. Once warm the right cylinder drops off at idle speed and the whole thing runs on one cylinder.
I have checked the following and don’t seem to have anything wrong:
-swapped out carbs off perfectly running bike and no change in behavior.
-intake and exhaust have no leaks (carb cleaner spray check method)
-both plugs are firing (used inline spark plug light to check)
I haven’t checked the compression or done a leak down test. My instincts tell me it’s electrical of some kind.
Any ideas or suggestions out there from people? I’m getting pretty stumped and could use some help.