Vintage BMW Motorcycle Owners

Earlier this year, I purchased a 1959 BMW R50 from a good friend of mine that no longer can ride the bike due to health reasons. The transmission is the S solo, and the rear drive is a 25/8. About 700 miles ago, the motor was rebuilt by Bench Mark Works with new bearings and pistons before closing for retirement.

I have over 600,000 BMW miles, but all on BMW bikes newer than 1996. This is my first vintage BMW 500cc bike, with all other bikes over 1100cc. At 60 mph, the bikes at a comfortable RPM. Over 60, its running at rpms faster than I like.

My question is since it has no tachometer, what is a good safe highway speed for the motor with my transmission and rear drive? Is there a rear drive better suited for faster speeds? The carburetors are the original Bing 1/24/45 &46.

My 1960 R60 has the S tranny and a 32/11 rear end (long legs). So, for the same RPM, it cruises at a slightly higher speed than the 25/8. Having said that, I don't take my bike on the highway (unless I can't avoid it); the lack of high-end speed (and the necessary associated high-speed brakes) don't really lend themselves to the safest cruising (strictly due to other highway traffic, with all its terrible drivers who don't share the road with bikes).

These are 60+ year old bikes and are not equivalent to modern bikes in terms of performance and capability--as your experience has made clear. Use your big bikes for the highway and save the R50 for local cruising--enjoy it for what it is.

An R50 is 26 hp, right? Not a lot for a heavy machine. You can certainly over rev it in lower gears but in top gear its power limited, not rpm limited. You can run full throttle in top gear and it will still slow down on hills. In top gear the engine can't pull enough rpm to hurt anything.

Sounds like you're suggesting that when you get to higher speeds, the engine sound goes up and up but the speed doesn't seem to keep up with the sound. Is that what you're saying? If so, maybe the clutch is misadjusted or slipping?

Kurt....not at all. I'm a mechanic, so the clutch is not slipping. I do understand that this is a 63-year-old bike with all the issues associated with the metals used during that period. I think Bill said it best with "In top gear the engine can't pull enough rpm to hurt anything." Thats probably the reason the bike has no tachometer.

OK, I just didn't understand what you meant that at 60 the RPMs sound OK but above 60 it's running faster than you like. As far as I know, once in 4th gear, the ratio of speed and RPM is direct so faster speeds mean faster RPMs. It is what it is.

It could be that it is a bit rough around 60 mph and runs nicer when faster. I have it like wise with my R25. Around 60 kph in fourth gear it vibrates the worst but gets a lot nicer at 70-90 kph. Don't be shy to rev these bikes, they are made to be "Vollgasfest".

These all have their sweet spot. My '59 R50 likes 50-55mph. Pretty much dead smooth there. It'll go 75 or a bit more, but with only 26hp, there's only so much there. I'm blessed with miles and miles of paved back roads with zero traffic. I can cruise them all day at 40-50 and the bike just loves that. Droning along on the highway at 55-65 is not the bike's cup of tea.

Dave

Let me clarify. My R50 runs great at all speeds with very little vibration. It's one of the smoothest bikes I've owned and as smooth or smoother than my 2016 R1200GSAW, 2004 R1150GS, 2004 Ducati ST3, 1996 R1100RT and 1996 K1100LT. But all of those bikes have tachometers and some run at higher RPMS. My Ducati's normal cruising RPM is 5000. I shift at 7000 rpms. The R50 top RPM limit is only 5800 rpm. At 60 mph, the bike seems like its running comfortably for its age and rpms (guessing around 4000 rpms). What I don't want to do is run the bike at over 5000 rpms that wouldn't sound high to my ears but may be for the R50.

Again, what Bill stated seems to be true for my R50. The weight of the bike with rider and low horsepower won't allow the bike to get near rev limits for this bike.

Ken,
A number of decades ago, I had an R51/3 that I used for touring. I put 30-40000 miles on it over the course of about three years before I decided to restore it. For the purposes here, it had about the same engine, carbs, etc. that you have in your R50. When riding on the interstate fully loaded, I mostly just held the throttle wide open for hours on end unless I was going down hill. It would cruise at 70-75 on the flat and drop into the 50's on hills, but it never missed a beat in all that time. These engines are limited by their small carbs, ports, valves, cams, etc. As long as you have a load on it, it is hard to "over rev" them into a dangerous condition. So, I'd ride it like you stole it, and enjoy it at its limits. Or just cruise where you're happy. They're hard to break.

Just one guys thoughts...