Vintage BMW Motorcycle Owners

I've been posting over on BMWST.com, because that's where I usually hang out.

Here's a link to my post over there, with a few pictures of the engine disassembled.

http://bmwsporttouring.com/ubbthreads/u ... Post552932

I can't offer much guidance. I just acquired a '52 R25/2, so I'm in a steep learning curve myself! If it were me (and I've done this already), call Vech at Benchmark Works. I looked on his website and didn't see any R26 cylinders for sale. But they'd know what some of your options would be.

Good luck...Kurt in S.A.

Go to ebay.de there are LOTS of cylinders,mostly used for sale that I have seen on there.

Thanks. Ron has been talking with Vech. He thinks he can bore it to first oversize and it won't need to be re-sleeved. I will go take a look at ebay.de.

I will preface this by saying that I know nothing about singles....I am a prewar twin guy and am learining about my newly acquired 1975 R90S.

I looked at your pix and my thoughts are:

It has definitely suffered a siezure event from looking at piston pix.
If it has been puched out to 300 cc (and your mech should be able to tell from mic-ing the cylinder bore), there is probably not much left in the cylinder. I would not sleeve it, but look for a decent used cyl. within the 1st or 2nd over size (0.5 to 1.0 mm)

I personally have a lot of confidence in Bill at BoreTech and would seek his advice for cylinders and pistons as well as possible crank repair.

http://www.bore-tech.com/

Almost anything is fixable at a price. I do not quite understand if your crank has spun with the bearingor if the bearing has spun in the case. If the bearing has spun in the crankcase, the case can can be built up and line bored by a good machine shop..not cheap, but possible.

I have no experience in building up cranks and re-machining them and I have heard conflicting reports on the success.

I spent a lot of $ and € to have a trashed R5 motor repaired because it belonged with the frame number. It depends on how important that is to you (I will admit to being a bit anal about some things) and this is a hobby for me, not an investment.

If you are looking Sunday coffee shop machine, I would take the less expensive route and would not spend a lot of money (say more than $500) trying to save the matching numbr case.

My €0.02. In any case, this is a lot of fun.

Bruce

Thanks Bruce. I've decided not to worry about the matching numbers. The engine pics shown are of my donor motor, which is the one that had the seizure.

My mechanic is tearing down the engine on my R26. He says it looks like the engine had seized at some point, and asked me about when the bike "stopped." The bike sat for 20+ years and I have no knowledge of a seizure event. My mechanic says it appears the engine has 50 to 60K on it in addition to having sat for so long. I thought the engine was in reasonably good shape because it ran.

It sounds like the engine is leaking oil out of multiple orifices and will also likely require a cylinder bore or re-sleeving. One of my acquaintances on another motorcycle site has suggested to me that some of the BMW's of this vintage are prone to overheating when the cylinder is re-sleeved.

I'm looking at this bike and wonder whether this is an issue on a "Sunday rider." I will go and take some pictures once the engine is taken apart, but I'm starting to wonder whether my R26 should just give up the ghost and become a donor bike.

I've already learned that the matching number engine had the crank spin on the bearing (at least that is my understanding) and so cannot be repaired. So it looks like I will end up with a non-matching numbers bike with the need for a very expensive engine rebuild as part of its restoration. Are there any specific things I should be aware of as I consider my options with this bike? Are reproduction cylinders available? Is re-sleeving the cylinder likely to lead to other problems?

Thanks.