New to this forum but I've owned and worked on my '68 R60 for (my god) over thirty years. I just finished a total rebuild of the engine with a lot of help from Cycle Works, Bench Mark Works and others. With over 90k miles on them I'm wondering if the rocker arms need any help. Has anyone ever rebuilt theirs? What were the symptoms?
I have owned 5 BMW's over the years(45+). Unless you have an racing cam (rennsport comes to mind) I have never had a problem with rocker arms, on the R50-S, R-27, R51-3, R-75, and the R69-S's. Adjusters can wear however, and one broke on the R-50S at fairly low mileage (600 KM). My current R-69S has over 200 K.
I suggest you address this to some of the professional restorers you have mentioned; that said I do most of my own work and was a professional MC mechanic back in the 1960's.
wlj1943,it is very cool to hear the R69's rocker arms can go 200K!Wow........are you on the original crank as well?How long did your valves & pisto/cylinders last before going oversize(s).......sorry to take it off topic,but 200K is quite a mileage,,,,,
To take it back on topic,I know that the R69s has needle bearing rockers and the R60 has the bushing type.There has to be specs for the clearance,however since it is a bushing,any excessive play would be easy to detect/diagnose.
The crankshaft was rebuilt twice, maybe due again-we'll see soon. Two rear main bearings I think. All the owners always cleaned the slingers promptly when any shiny metal was found on the drain plug magnet. We also have a bigger magnet in the aftermarket aluminum oil pan. Oil changes every 2400 miles; regular valve adjustments every 3600; drop the pan every 10K or so. Fluid changes as recommended. It is on the second set of jugs, currently on first oversize. Valves and guides have been replaced at least 4 times to my knowledge, last time by me. We always added lead substitute or the real thing, now I use avgas or racing fuel whenever I can; hard starting though. All also used aircraft engine oil; I think that was a big help but cannot prove it. Not sure about the needle bearings, but the shafts were unmarked when I did the last top overhaul about 10 K ago and 8 years back. Piston pin bushings with most top overhauls if I remember correctly. This bike was owned by 3 people, including by me twice. I have had it this time for about 10 years, and it is currently just starting to undergo a full restoration. One of the previous owners used it for commuting most every day in California; about 80 miles a day for many, many years; that's where most of the miles accumulated.
I have observed over the years that bikes that are not ridden regularly die quickly, caused by corrosion.