Cylinder Re-boring - R90S Remaining Issue

[hank0614]

Thanks for all the replies. My friend has one question: where is the spigot measured to determine whether it is a small 97mm or a large 99mm spigot? Is it at the base or the largest point where it enters the engine case? As the bike was built in 10/75 he may be at the point of change over where BMW was using up what small spigot clinders were left in inventory.

Thanks again!

Hank
'72 R60
'95 K75S

[George Ryals]

The largest part that enters the engine case.

[Kurt in S.A.]

A 10/75 build should, theoretically, be the larger opening. Unless BMW was using up spare cases left over from the '75 models which ended in August 1975.

Kurt in S.A.