I have a 1971 Commando which is currently blowing oil into the Primary Chaincase. I have checked and replaced the crankshaft seal to no avail... I've had the bike since 1979 and put many years of riding on it before without any problems. However, for the last several years this problem has existed. Although it was a pain at first, I solved the problem by draining the chaincase every now and then; however, now it seems to fill up within a 100 miles which has made it basically unusable. Any suggestions would be appreciated

Chances are high that the oil pump has degraded and no longer scavenges the sump adequately anymore. I've correctly diagnosed this before though it may or may not be your problem. Pumps are expensive and "reconditioning" is not always sucessfull because there are 4 leakage paths in the pump and the shop manual recon only addresses 1.

dynodave, thanks for the response - I'll give it a rebuild and see if it helps... ron

rwanzer, Did this solve your problem? How about anyone else? Have you had this problem and solved it? I will appreciate all the help I can get before I start the job.