Motorcycle Repair: Yamaha 85 FJ1100 oil leak, crankcase ventilation, crankcase pressure

Question
I was wondering if you would have any ideas about why a leak would keep occurring after we've replaced the countershaft seal and a crankcase seal back by the front sprocket.  Everything seems okay, but after riding it for a little bit, the leak reappears  from a different spot.  It is coming from a location under the sprocket case where wires run up to the oil sensor.  We're really confused on whats going on.  Thanks.

Answer
Frank, I really don't have much knowledge about Yamaha questions. Hopefully, your oil seal installations went well. That can be challenging to do w/o splitting the cases on most machines. Clean the area real well and then take it for a ride. Old timers use spray foot powder to help locate and track oil leaks, when they are not easily visible.

Check the shift shaft seal, as well as the oil sender for leaks. Hopefully, there isn't any oil leaking from the case seams. Make sure that the crankcase ventilation system is all open and functioning. Any restrictions will cause crankcase pressure buildup, which will aggravate the tendencies to leak oil at seals and seams.

Try..
http://autos.groups.yahoo.com/group/yamahafj/
for further assistance...

Bill Silver