Hi, What are the symtoms of worn crank seals ? Is it erratic idle, easy stalling, hard starting and poor low RPM power ? The bike is a very old YZ50 with points ignition. It does have worn crank bearings and as a result likely the seals are leaking. Thing is it idles and starts just fine but I dont seem to be able to set the ignition correctly I am having to retard it allot just to get some low end power if I set it to 1.8mm BTDC you just cant ride it as it completly bogs down at anything less than screaming. I believe it is bored out to 65cc if that makes a difference. If you feed in the throttle gently with incresing RPM it is better but if you crack open the throttle at low RPM you just start slowing down and it dies. The worn crank bearings could well be upsetting the ignition timing as the cam is on the flywheel and will in effect vary the points gap hence timing.