R25/2 Camshaft-Crankshaft Alignment

[Kurt in S.A.]

Can you direct me to info on how to ensure that the camshaft and crankshaft are aligned correctly for the chain installation?

Thanks...Kurt

[Kurt in S.A.]

[Taz]

Hello Kurt.

It's rather simple...put the crankshaft in TDC position, then rotate the camshaft until on the sprocket  the gap following the third tooth counterclockwise from the left big hole (the ones for the camshaft bolt, it does not matter which one you go for) is exactly in line with the centres of the camshaft and the crankshaft...see picture.



Sounds frigging complicated, once you have seen it on your machine you will never be unable to unsee it

Note: picture taken from BMW's R27 maintenance manual, page 66, fig, 74, for illustrating purposes only...

[cwf]

Hello Kurt, in theory lining up the two marks is fine. I have an R 35, which obviously is older and has a more chequered history. So I lined up the two similar marks and the bike would not run smoothly, because the crank and cam were one tooth out, despite the marks.

It's probably worth just checking the cam is also at tdc before bolting it all up.

Charlie.

[Kurt in S.A.]

Appreciate the info.  I don't have a lot of experience with bottom-end rebuilds, but on things like V8 cars, and even my R100/7, there are physical marks that need to be aligned.  Just seems like that would be mo-better!!

Kurt

[Taz]

To my knowledge there are no marks on these timing chain sprockets...it's about alinging the correct tooth gap with the connecting line of the two shafts...