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This page is about the BMW motorcycle models R60, R69, R60/2, R69S, R60/US,
R69US.
Mark asked via email on the slash 2 Yahoo group list.
Duane,
I'm surprised to hear that the S, with it's higher compression, would be
more reliable. What was different about the R69S vs. the early
long rod
R60? I'm familiar with the rear bearing change, the compression
increase and the larger carbs. Was the cam different?
Or could it be more a case of the increased hp allowing these engines
to run at (aircraft terms here) 75% power more of their life than at 100%?
Mark, To answer that question takes some time and delving into other areas
besides mechanics. Short version. The Interstate system was funded
by Eisenhower in 56 (I think) and it was some time till we had lots of high
speed roads. I think that the early /2 models didn't see the abuse that we
expect today as normal. The few BMWs in the USA were mostly in cities,
where they may have seen lower speeds too. I wasn't riding BMW until 62 so
I am way out on a limb here. Since I was young and poor I rode the early
/2 bikes, but I wasn't in the business yet. It was common for one to go
75-100 k miles before the crank needed attention. The R69 got great mileage
before it needed top end work. The early engines had a good reputation.
It was in 1960, on the R60, when they went to the 4 ring piston that I first saw
trouble.
In the 60s many different reliability issues started showing up.
It isn't one simple issue. See my page for detailed info on the evolution of
/2 BMW heads and the problems. The R50/2 and
R60/2 heads failed often in the first year. The pushrods were prone to
bending. The cranks
started having problems. The rear mains started spinning on the crank.
This issue reached it's zenith in 1967 on the R60/2. Everything about the
engine was trouble. The pistons were seizing up right and left.
Later I found out why, but that's another story on the
piston page on this web site. One large problem is that the R60 rear
main was a ball bearing. The R68, R69 and R69S use a spherical roller that
allows for lots of crank flex.
We finally realized that the 1967 R60/2 was so bad that by 1971 we wouldn't
take one on trade. I parted out several of them. Many didn't get 25
k one a top or bottom end. I have seen many not even reach the warranty of
6000 miles before the bottom end was out. I used Roy Reynolds, in Salt
Lake City, to do my crank work and even he got discouraged. I tried
Flanders and they didn't have good quality control. One block was full of
sand when I got it back. Reynolds was the best west of the Rockies.
I built a special box for a lower end and it was reusable. It made
continuous trips back and forth for a few years. Once I had 3 new cranks
from BMW and 2 weren't made correctly and had to be rebuilt before using.
Plating and welding were tried to build up the rear of the crank to fit the
bearing. The welded ones cracked and broke off. The plated ones were
better, but not as good as original material.
Summary of the comparison of the R60/2 and the R69S BMW Motorcycle
The use requirement went up as time went on. The
quality of materials went down during that same time. BMW sales went way
down world wide, as a result, and BMW almost stopped making bikes. Instead
they redesigned the whole thing and did a great job with the /5. It was
two years before I could fully appreciate it, but the /5 is a better bike in
almost every way than the /2. It isn't as elegant, smooth or as soft
riding, but the /5 lasts and costs less to maintain.
Restoration
They both cost about the same to restore. Why in the world would
someone spend about the same money on a R60/2 that was fraught with reliability
problems?
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