1961 BMW R50S
Looks like this very nice R50S is back up for auction. I have had to re-list items before because I was hoping for more. Were my expectations a little high? Probably. But with something as nice as this I would hope seller and buyer could meet.
Pre 1970, Earles Forked BMW are not the first thing that you think of when you think or a sports bike. When you use a shaft to transfer power to the rear drive, you think of luxury, not speed (well, MV Agusta did have some speed). But in 1960 BMW added a 500cc sport bike to their line up in the form of the BMW R50S, and this 1961 example offered up on eBay now is a very well put together example.
From the seller
This is a freshly restored R50S with no expense spared, all numbers matching including the original data plate on the steering head, and the correct carburetors, speedometer and final drive. The frame, forks and swing arm are powder coated and all the sheetmetal was professionally painted and hand striped. The engine and transmission was completely rebuilt (including crankshaft) by David Carmean, the breather was updated to the later /2 style for dependability, and the cylinder heads were completely rebuilt by Randy Long. The bike was restored using all stainless fasteners from Blue Moon BMW as I intended to ride the bike, but I will include all the original fasteners with this sale. The mufflers are “NOS”, and it has an original deep sump Bowman oil pan which is a very desireable accessory.
When you look at the number comparing the pedestrian R50 to the Sporting R50S, you have to wonder why BMW only offered them for 2 years, and why only 1634 units were made. Starting with the normal 494cc R50, you would see a CR of 6.5:1 fed by 24mm Bings giving you 26hp at 5800rpm. This was good for a top speed of 87mph. The R50S bumped the CR up to 9.5:1, took its breath in through 26mm Bings and delivered 35hp at 7250rpm for a top speed of 99mph.
So why only 1634 units sold? I think you have to look at the other changes made to the engine to deal with the extra power. There were none. The same crank, the same con-rods, the same rocker arms, and the same intake valve, the exhaust valve had a 1mm larger diameter stem. So 1.34 times more horsepower, 1450 more revolutions per minute and 3:1 more compression ratios, gives you a greater possibility of trouble.
I don’t know of to many riders who shop for a sports bike who are not going to find the edge of performance, and this apparently happened with the R50S. All the numbers lead you to believe that BMW had a winner, but only 1634 were made before they pulled the plug. Yes, the 600cc R69S may have been a factor, but why not offer a sports bike for the 500cc line?
This 1961 BMW R50S is one of the most collectible BMW there are today. The fact that they are a sport bike and were produced in limited numbers will do that. The debate has been for the last 30yrs is why did BMW pull what appears to be a winner from production?BB