Vintage BMW Motorcycle Owners

I am not sure but if you decide to install a different flywheel, check the number of teeth or part number. St.

Also check the taper match between flywheel and crank.

Thanks for the reply’s, If I do anything with the flywheel it would be to have it machined to the correct specs.
Jim

Well here is a update (sorry it’s so late) I had the flywheel machined to match the others and put it together. Some measurements I made during reassembly. Crankshaft end play at .004, Face of transmission input shaft to pressure plate .100, clearance of pressure plate to end of pushrod .008 (with the new clutch cable adjustment of 201mm at transmission and 2mm at lever).
I took the bike out to the freeway and at 4,000 rpm at 75 mph 5th gear hit it full throttle 3 times with no slipping (roll off at 6,000 + rpm). I went for my 60 mile loop ride and just before I got home with everything nice and hot hit it again. At about 6,000 rpm I felt a little slip!
Obviously the machining did help but maybe I need more off. The bike has always shifted very smooth, clutch has always felt smooth. I am going to ride it for the rest of the winter and see what happens.

Jim.

Time will tell! Interesting...I didn't think that the flywheel could be machined...I don't find any specs for it. Typically on cars, that's what you do. Haven't heard much about on the BMW.

If you are not familiar with the BMW flywheel — clutch assembly the flywheel is not a part of the clutch itself but the step in it will determine the spring pressure against the pressure plate. If it is not machined correctly at the factory as mine seemed to be the spring pressure can be low. Some people that build race motors will machine the flywheel to increase the spring pressure.

I was just saying that I'd not seen any specs about turning a flywheel. Somethings on the bike are already at minimum thickness, such as the front disk rotors.

Well the clutch started slipping again real bad so I pulled it all apart again. I noticed that the clutch disc looked like it had some oil on it but the transmission seal was not leaking at all and the disc center was dry. I sent everything to Southland Clutch and they said that the clutch disc had oil on it from the outside in! What??? I looked at the crank case breather hose and found it was cracked at the nipple allowing the oil saturated air to fill the starter housing all the way to the clutch housing and coating the disc. I replaced the hose and will see what happens now.
If anyone else has a strange clutch problem maybe check the breather hose.

Nothing better than finding the fix! Good job! Great diagnostics and persistence.
Jeff