Leaking Base Gasket? '74 or '75 R90S?
Posted: Tue Sep 22, 2020 6:46 am
If you own a '74 or '75 R90 or R90S and your engine cylinder base gaskets leaks, here is some help:
When I rebuilt my '75 R90S 11 years ago, to help seal the bases of the engine cylinders, I used the sealant "Suzuki 1207B Silicone Gasket" and have not had a leak at the base gaskets since. I think "Three Bond 1207B Silicone RTV" is likely the same product but I used the item listed as "Suzuki", see above.
Tom Cutter worked for Butler & Smith during the time of those motorcycles and has related how Butler & Smith had so many warranty claims for this problem, about 80% of all motorcycles during that period, that they had to hire additional employees to handle all the warranty claims for this problem.
The problem mostly went away with the introduction of the '76 models since BMW was getting the block ready for the introduction of the 1,000 cc engine in 1977 and altered the block to resolve this situation.
When I rebuilt my '75 R90S 11 years ago, to help seal the bases of the engine cylinders, I used the sealant "Suzuki 1207B Silicone Gasket" and have not had a leak at the base gaskets since. I think "Three Bond 1207B Silicone RTV" is likely the same product but I used the item listed as "Suzuki", see above.
Tom Cutter worked for Butler & Smith during the time of those motorcycles and has related how Butler & Smith had so many warranty claims for this problem, about 80% of all motorcycles during that period, that they had to hire additional employees to handle all the warranty claims for this problem.
The problem mostly went away with the introduction of the '76 models since BMW was getting the block ready for the introduction of the 1,000 cc engine in 1977 and altered the block to resolve this situation.