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Re: R60/2 my first /2 engine rebuild
Posted: Tue Dec 07, 2021 5:22 pm
by Flx48
A suggestion to add to those thoughts offered by James and Michael-
Perhaps have the cylinders evaluated by someone competent to do so, be it you or someone else, to first determine the depth and extent of the pitting and scoring, before deciding what size replacement pistons to acquire.
It's pretty difficult to meaningfully assess the extent of damage only from pictures.
Best-
George
Re: R60/2 my first /2 engine rebuild
Posted: Wed Dec 08, 2021 4:27 am
by 808Airhead
They are cast iron cylinders. Buy the next size up pistons and have it bored correctly and will be fine, It could have ran lean or hot on that side,or lubrication fault,but you will be throwing those pistons away so it doesn't matter.
Re: R60/2 my first /2 engine rebuild
Posted: Wed Dec 08, 2021 9:56 am
by Kurt V
Well, here are the pistons. The one with the semi circular groove close to the edge is the right piston. Not sure what caused that. The one that has the pitted cylinder bore. Is a 72.96 mm piston one over or is it standard? Thanks!
Re: R60/2 my first /2 engine rebuild
Posted: Wed Dec 08, 2021 10:41 am
by schrader7032
Well, the standard bore of the cylinder is 72mm and I believe first over would be 72.5, and second over would be 73mm. So if your cylinder matches that sort of thing, then you would be heading for third over. It would certainly be wise to get the cylinders measured as well.
Re: R60/2 my first /2 engine rebuild
Posted: Wed Dec 08, 2021 10:44 am
by wa1nca
Re: R60/2 my first /2 engine rebuild
Posted: Wed Dec 08, 2021 6:32 pm
by Kurt V
Tomorrow I’m dropping the engine and cylinders off at a local motorcycle shop. The owner is a long time owner of vintage BMWs and has rebuilt a number of /2s. I’m going to get him to analyze and do the necessary repairs.