I have a 1978 BMW R80/7 that I have owned since new. This bike has approximately 75,000 miles on it. The transmission has developed a loud whine when in 3rd gear between 4,000 and 5,000 rpms. No grinding.<p>I have always serviced the transmission regurlarly ( at least every 10,000 or so miles) and I have run sythetic gear oil in it for at least 15 years. The last time I serviced it I used Royal Purple brand before that Mobil 1.<p>I am not hard on the bike but I am curious why 3rd gear instead of 5th gear where the bike spends most of its time. When I ride this bike it is for long distances such as Texas to Alaska or Texas to Canada. My question is; what is going on inside of this transmission and what do you think the fix will be?