Compression test <- make it a priority for Waldo.
This is a discussion on 1993 BMW Boxer Oilhead R1100RS Cafe Racer Build within the Project Builds forums, part of the Caferacer.net Forums category; Originally Posted by TrialsRider Damn! I just lost another perfectly good post to the ethernet :| If you figure out perpetual motion keep hand written ...
Compression test <- make it a priority for Waldo.
Rear differential. This was quite some job to clean up, was fully covered in grease and stubborn oil. However, slowly but surely I managed to remove most of it. The axle had loads of dirt inside. The bearings are a bit scruffy, however, they do seem to work alright, so hopefully won’t have to rebuild this. It does have some flaky aluminium oxidation at the end, which I need to decide what to do with. Previous owner applied some kind of silver paint to it, however, it all stripped when I applied brake cleaner to it. I believe my options are to repaint it again using more durable paint or take it completely apart, send it to vapour blasting and then powder coat it.
At least it looks like its all clean and neatly organized. Unlike my shop which often looks like a few cars and bikes exploded parts and tools all over and I can never find the godamned 10mm socket or one of my 40 spark plug gapping tools and then Im just getting pissed and glad that I keep a glass bottle Pepsi machine stocked with cold beer.
Dream as if you live forever, Live as if you die today.~ James Dean
I feel the need, the need for speed.~ Mavrick (Tom Cruise before he was a big ol' bag of crazy)
Is called the final drive assembly
"differential" would imply you have 2 rear wheels that need to change speed relative to one another to go around corners.
You can easy find video on the net to show you what is inside there, I would be inclined to leave it together unless you absolutely suspect a problem. The bearing is critical as that is what you and the entire bike is riding on. BMW in typical fashion built it very sturdy, mine is different yet very similar, it survived a rear end collision by a truck 32 years ago and so far my rear wheel has stayed on there. ymmv.
if there is oil in the rear drive then in the photo it's getting into the breather and may be inclined to piss out once it's up the right way and fitted. they can be a bit of a pita. we had to rebuild a few k1200lt ones and that wasn't fun. the pivot bearings at the front get lines across the inner cones, so check them and replace if in doubt. like a lot of stuff on these, there's a specific tightening procedure, and the really good loctite is required. the green 270 is what they recommended, we used that or wurth green. not sure what the equivalent is now.
those engines are pretty durable. we saw a few round the world type guys on gs that would need the heads done because they'd got hot transversing a desert crawling along at 6,000 rpm in first sort of thing becuase they were carrying 150kg more than recommended, and the guides were loose. think we had a trade in run the mains and big ends too, but that was the only one i ever saw the cases open on.
although if you use the alleged 125 often it might not be so.
looks like typical uk winter salt paint damage. when you have the white corrosion under the paint, your only option is stripping, some sort of blasting and redoing properly in paint or powder.
If I can add my two penneth.
Remove the drain plug first, if the oil is reasonably clean, and there's nothing nasty attached to the magnet on the drain plug the bearings may well be okay. If the bevel box was covered in oil, and grease you may well need to replace a seal, but who knows?
If you just want to repaint it you should be able to get a decent finish without pulling it apart, just lots of time rubbing down, and careful masking before spraying.
Rebuilding the bevel box isn't easy, special tools required, bearings to be shimmed, best to send it to a specialist.
"It's better to keep your mouth shut and appear stupid than to open it and remove all doubt"
Personally if I were you, i would follow Stevo's advise. I'm not a BMW guy, but have the necessary tools and hydraulic press necessary to do a Honda one. If there is crap attached to the drain plug, then you may want to gamble on a used one off of Ebay. Needed one a while back and found one on Ebay that ended up costing almost nothing. I prefer to spend my time strolling to the mailbox rather than farting around with backlash and preload unless its interesting valve gear. The first thing I would be doing with that bike... (well not that bike,because if I was going to buy a basket case, then it be a little different) is sorting out the inventory. There are bits that could be damaged or missing that are a game changer, so best to figure it out before you start spending money.
Last edited by Cyorg; 04-26-2019 at 08:22 PM.
"Non urinat in ventum"
Thank you all for such a great advice and even to those who made comments of how ridiculous this project is.
Ready for cleaning. It’s badly pitted though will see what can be done about that. Firstly need to remove all that grime and grease, which accumulated over the years. It seems previous owners did not really care too much about painting preparation and simply spray painted over all the oxidation and dirt. Will have a go at it with brake cleaner from Screwfix, engine cleaner from Eurocarparts, Isopropyl Alcohol, which I have borrowed from laboratory (essentially 99.9% pure alcohol) and some heavy duty mixed degreaser from Screwfix.
After around 6 hours of scrubbing, rubbing and sanding, I am starting to see the light at the end of the tunnel. Identified few problems along the way. The major one is that pins for the exhaust headers snapped and are rusted inside, so these will have to be somehow extracted. One of the pins does not even have the mounting hole, has been completely ripped apart. Talked to an expert, suggested to get these pins extracted by drilling them out and then cleaning the threads using a tap. However, it seems the one that has been completely destroyed. Also battery mounting bracket bolts, that screw into the engine seem comfortably rusted in. These have rubber vibration dampers, which hold battery bracket, and also have been twisted off.