1971 R75/5 questions??

Greetings, I’ve been gone since I traded the 82 R65 I was working on a year or so ago. I recently picked up a 1971 R75/5. The bike has 65K miles on the clock, however the bike has indication of being stored in a happy place.

Here’s what I ve found so far:

The compression measured 145 on both jugs
The right side push rod tubes are leaking
The carbs may be ok. (Pulled the bowls and they weren’t gummed up)
The right side smokes on start up, I think the crankcase vent may need to be replaced.
The oil psi light doesn’t work, I will check tomorrow, hopefully it’s the wiring, which has some issues.

If anyone can suggest other things to check, please let me know.

My hobby is building old british bikes, although I’m fascinated with these German machines. I liked the R65, but traded it for a 67 bonneville project. I hope this bike proves to be as good as the R65 turned out to be. I am a little concerned about what I consider to be high miles (a british machine would’ve gave up on half that many miles).

Thanks for all replies.

Phil

Looks like a nice project, Phil! There are some non-OEM items in/around the bike, so you might suspect other changes as well. I'd certainly verify that the brake linings are up to spec...might see the front getting thin after 65K. I'd also want to inspect the input splines to the transmission as well as the rear wheel splines. Make sure they're cleaned and lubed. Of course, you should do a check of head bolt torque and then check the valve clearances.

'71 r75/5

Your bike is 100 percent totally off the chart cool.

20774, I’m not as well versed on these bikes as I am on the triumphs, the saddle bags are off already, I don’t think they are correct for the bike, but they do have a cool look. I think the seat is fairly new, and the tank looks too good to be 46 years old. What else did you notice that wasn’t stock? Should it have side covers to hide the battery? Also, You are referring to the drive spline, that drive the rear wheel?

I’m going to see what the engine needs, and address the wiring issues before I start on the chassis. I need to be able to roll it around, beside I have my son in laws old Honda on my center jack stand, till he get some tires. Thanks for the tips.

Thanks for the compliment barryg.

65K Miles is not much on an R75/5. Good looking machine from a Happy Place.

That appears to me - to be a stock "big" tank for that bike, and those are period correct Wixom saddle bags to my eye.

No side covers for '70 and '71 /5's. Wixom saddle bags are not oem saddle bags for BMW's, but they are a really popular period aftermarket saddle bag.

I don't think your mileage is an issue. My '71 R75/5 has 101K miles and still runs well.

This video series would give you an idea about checking components on your /5. There are 10 videos in the series to date, and if nothing else, I think it's entertaining and informative to watch.

The disassembly starts in 2nd episode.

<iframe width="854" height="480" src="https://www.youtube.com/embed/pdAjgJyJoVE" frameborder="0" allow="autoplay; encrypted-media" allowfullscreen></iframe>

I guess I see some cosmetic "additions"...the seat looks to have recovered (nice grab rails, though), extra reflectors all over (maybe not a bad thing??), highly polished valve cover. What are the carb numbers...I wonder if they're correct for the /5. And weren't the air tubes a silvery gold during this time period?

As for the "drive spline"...when you remove the rear wheel, you'll see the splines on the final drive and the mating splines in the wheel hub.

Tehran, thanks for the link, very good, they show you things that you need, and breeze past things we should all know. When I first started the British bike hobby over ten years ago, the only videos I could find was a drunk Australian, who’d cut up cereal boxes for gaskets.

20774, I think the seat is a new replacement, and I kind of think the tank may be new also, or at least it’s been professionally restored. I know what to look for on the drive splines. I will probably pull the gear box as well, there seems to be some leakage toward the back, around the drive side gear box gasket. I’m not sure, it may be coming out around clutch plunger?

Thanks again for all the tips.

Also have a look at some of the threads/pictures of other R75/5 teardowns listed here:

https://forums.bmwmoa.org/showthread.php?50991-Rebuild-Sites-with-Photos

extra reflectors all over (maybe not a bad thing??)
The reflectors on aluminum turn signal housing were oem for all '70 and '71 models. It changed a little for the '72 and '73. Not trying to be a know it all but I had a '71 R50/5 for over 30 years and I studied it to death. Yes my carb intake tubes were silver that slowly turned a an odd gold over time. It would not surprise me that replacement intakes would be black.

Nice Bike

I had a 71 R75/5 back in the day. Rode it Seattle Ft Lauderdale after they let me go home from RVN. Crashed it, grabby front brake. Painted it Chrome Yellow with black pinstripes. Was my third BMW. Memories...