Hi Folks, I recently acquired a nice American import K1. However, it was running poorly...idling too high, seeming to miss and carry on under throttle etc. The bike is completely stock, including the 4 into 4 exhaust.
So an initial check revealed a faulty plug cap on #3 cylinder. After replacing same, the bike still ran poorly. So I took off the carbs and gave them a full clean (removed and cleaned all brass, ultrasonic clean of carb bodies, slides.) Reinstalled brass, set float levels (all were out!) and carried out a bench sync. I also replaced the rubber "insulators" beween carbs and head. Then I checked and adjusted tappet clearances (they were close to correct). Primary and secondary coil resistances were checked and were in spec (4.5Ω/14.5kΩ).
Before vacuum sync, I checked that the points timing was correct...it was. Carbs then reinstalled along with stock airbox and filter.
I proceeded to vacuum sync, and although the sync tool (Syncroking 4 MkII) indicated full carb balance at idle, it still ran a little "lumpy".
Increasing throttle opening still showed very good vacuum balance but bike still didn't sound or feel right. I double-checked my procedures and compared the Syncroking with a mercury manometer. Both indicated the same good result.
So I popped the tank back on and went for a quick ride, and it proved that something was not quite right....it felt lumpy unless throttle was cranked open. Closing the throttle brought the bike back to normal idle, again a little lumpy however.
Sorry for the long ramble but I'm at a loss as to what could still be causing such "rough" running.
There are many on this forum far more experienced than I so I'm hoping someone may have an aswer for me.
Thanks in advance!