I want to take the topic further.
I found a good (and verry cheap) k1100 engine sourced from a crashed bike. Thing is that it is not having the whole oil pan. Maybe for legal issues they have to keep the part with serial number.
Can I use my k100 oil pan on this k1100 engine block? I have done some engines till now, some of them racing ones but I did not open yet a K engine.
My initial plan was to build an 1000 cc performance engine using lighter k1100 crank and k75 high compression pistons, I sourced the parts I just waited the winter to start building. But 1100 engine sounds attractive now as there is no replacement for displacement.
What do you think?



Made a new topic for you, to keep the other topic clean for the original topicstarter

Arlina

 Arlina thanks for relocation

Duck pointed me in a good direction.
Indeed there are output shafts bearings location machined while the block assembled together. 
but.. I see this part on ebay.
If I am not mistaking there are ball bearings so the gaps are not so tide. I think it may worth trying some gap measurements. Even tough is old tech I have high expectations on BMW German precision. If it would be Russian made I would not have any hope.

Thinking to keep oil pan /output shaft case swap as a last resort for now.
In the mean time I tried to focus on my initial engine upgrade plan witch means replacing pistons for k75 new ones and the crankshaft for a lighter k1100 one.
Thing is that apparently there are no more k100 conn rod bolts available.
So I am asking comunity about knowledge regarding reusing old bolts and k1100 conn rods fitting along k100 /k75 pistons since k1100 bolts are still available.