muskallunge

XS650 Enthusiast
Messages
44
Reaction score
5
Points
8
Location
Livingston, MT
My 1978 xs650 hardtail chopper has been running rough after it warms up and I let’er rip on the highway, typically past half throttle. It seems like it starting doing it after I adjusted the cam chain tensioner. Carbs cleaned and didn’t change anything. The main jet size has been fine in the past. Spark plugs getting old? Carbs need sync? Do I need to adjust my points? I do have a small oil seal leak on the left engine points cam shaft. Any advise would help. Thanks
 
The tank should be venting properly as it’s a tc bro’s narrow alien with a cam lock style vented cap. I have UNI filters that I recently cleaned with gasoline, then massaged oil into as suggested by a thread on this forum. Think that might be restricting the airflow at high rpms?
 
Using heavily oiled filters could make it run rich. Fuel filters also could be plugged, what carbs? Pull a plug after high speed shut down, lean or rich?
 
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Also yes points can, do, wear, pit, get oily, out of gap.
Condensers fail.
Watch points in a dark area while motor is running, a little light sparking is OK, heavy sparks points at a failed condenser. Check voltage to coils should be right up at 12 volts. dirty connections switches loose wire. Is the charging system working good? Montana, has it been sitting? fresh gas?
 
How many miles on the plugs? Yes, they do wear out and need replacing periodically. These bikes, particularly the points models with their wimpy stock coils, are tough on plugs. You usually need to replace them about every 4K miles. I once ran the plugs in another bike to around 10K miles and it started experiencing symptoms similar to yours, not running right at highway speeds.
 
Nothing to add to your current problem just something for next time you clean your foam filters.Gasoline can dissolve the glue used to stick the filters together, use hot soapy water or even water soluble engine degreaser spray in preference.
 
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