I modified my 1976 R90/6 a couple of years ago:
Siebenrock 1000cc, Dellorto 38mm carbs, Ted Porter dual plug heads, R90S drilled air box, OSHMO lightened flywheel, tall gearing (32/11 rear drive, rebuilt transmission by Boxer 2 valve with tall 5th gear). It revs up much quicker and pulls stronger than stock but in 6000 miles I gone through 2 new clutches, one stock BMW and the other from Southland clutch. Anyone have any experience with the Siebenrock oil resistant clutch? Anyone know of any other set up with more friction? What kind of clutch do sidecar racers use?
Curtis #2811
When you say you replaced the clutch, do you mean the friction disc and the diaphragm spring ?
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
Yup. The first time around I bought the whole kit from Bob’s. Friction plate, pressure plate, heavy duty spring, etc. Powered through it in 4000 miles. Second time I sent it to Southland Clutch. They machined it and bonded their own friction materials. Lasted 2000 miles. I might call San Jose BMW and see what they used on their race bike.
Assuming that oil seals on the engine and gearbox are oil-tight and you are not actually fighting an oil-on-the-friction-plate issue, then that would be my advice.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
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