Oil Pump Rotor Indexing

[AKtim]

I've sent my 77 R100/7 transmission out for an overhaul. In the meantime, after positioning the engine at TDC with the OT in the window, I pulled the flywheel (yes, I blocked the crank) to replace the rear main seal and oil pump cover o-ring. When I removed the oil pump cover (it had been upgraded to bolts) I noticed the inner rotor did not have an indexing mark. When I removed it, I saw that sometime in the past someone and misassembled it as the indexing mark was facing in. The weird thing is with the inner rotor turned around the right way, no matter how I rotate the outer rotor the 2 indexing marks will not line up. Also, I noticed that the pictures in my manual show the cam/inner rotor key way on the bottom, and on my engine it's on the top. I personally only put about 400 miles on the bike since I bought it (it was a "barn find"), but who knows how many thousand of miles the bike was ridden with the oil pump assembled incorrectly. And if the oil pump rotor's positions are important enough to warrant indexing marks, how could the bike have run at all this way???? And no, the engine has NOT been rotated at all. Any thoughts, ideas, opinions or theories would be appreciated Thanks!

[chasbmw]

I have just replaced the oil pump rotor on my 75, with the square drive rotor which fits onto my new camshaft. There were no indexing marks on the new rotor, but I did have to look carefully at it to make sure it was not back to front.

[Duane Ausherman]

I know of no indexing marks, so they may have been put in by a PO. Don't worry about it.