Vintage BMW Motorcycle Owners

Hi

I was looking for a R90/6 but decided to also consider a /7 model.
Is there any good info on the subtle model and mechanical changes that occurred between the end of the /6 range and say 1979.

I really dont know the precise questions to ask.
For instance, do all /7 bikes have the squared off rocker covers?
When were the last engines built with the double row cam chain.
Do the /7 bikes have the hydraulic steering damper like the /6 bikes?
What are the model improvements of the /7 over the /6.

Its stuff like that will make it easier for me to think about which series to hunt for.

Thank you in advance for any information or links.

Regards


Mal

For instance I heard that the snowflake cast wheels had a problem.

Does anyone have information on that issue?


Thanks


Mal

Mal -

I like the /7 model as it marked the high point for power, etc., before the US EPA began to demand changes to timing/tuning resulting in losses in horsepower. Snowbum has a long page on Airhead differences...towards the middle he has a section on the /7 models:

https://bmwmotorcycletech.info/models.htm

Things that I'm aware of. Yes, they all have the squared off rocker covers...more pleasing to my eye. I don't know details about timing chains. No stock hydraulic dampers, although I suspect the R100RS models did. I believe the /7 had stiffening in the frame with an extra element between the down tubes as well as I think the backbone was thicker or maybe the shape was changed to add stiffness.

The 1977 model had a mechanical tach while the 1978 started with electronic tachs. Another major changed happened with the bikes produced beginning January 1, 1978. This is when the EPA regulations kicked in and the timing was changed. My bike is a Sep 1977 build date so I think I have the earlier timing.

My bike has spoke wheels which seem more appropriate. Snowflakes built before late 1982 had a potential to crack. There was a recall which technically is still in force. But finding a replacement is getting to be hard...BMW made only so many. Dealers can be strict about honoring the recall if you don't have original purchase papers or the listing of VINs show it was already dealt with. I don't think cracks were ever discovered in normal use bikes, but they did show in bikes ridden on cobblestone roads. Another issue is the porosity of the rims. They are designed to run with tubes although people have run them without...I guess one takes your chances! Plus the rim shape is designed to be more effective with tubes.

Here's Snowbum's article on the Snowflake recall:

https://bmwmotorcycletech.info/19inchrecall.htm

Kurt

Thank you so much for the links and your personal experience.

I will spend some time checking out those links before I make my mind up.


Cheers


Mal

I don't know if I can add anymore information than Kurt provided.

The R90/6 series bikes are wonderful bikes for their production run with the R90S at the peak of the hill power and looks wise. So, you won't go wrong buying one of them in decent condition. The plain Jane bikes are for the most part reasonably priced, the S bikes can get expensive due the desirability factor.

The /7 bikes started their run about 1977 with a line up I know of with 750 and 1000 models in plain Jane dress. The real kicker for 77 was the introduction of the R100RS. like the R90S before it, it was a game changer for BMW. The first year 77 RS was equipped with a drum rear brake, spoked wheels. Later year production runs saw a few bikes with the snowflake wheels and disc rear breaks.
Early snow flake front wheels had a recall on them, it has been so long ago I have forgotten the details. I kind of doubt you would find a recalled wheel on a bike now.
I have a 78 RS and like Kurt said, it is the highest powered stock airhead. I can't say for certain but 77 and 78 were the two years of higher output with maybe 79 as well. 1979, the R100RT was introduced as a more upright seating position touring bike. The RS was a sport touring bike and I will admit it can be a bit hard to ride on. I have a 84 R80RT as well as my RS and I find I do most of the riding on the RT just because the upright seating position is more comfortable.
One thing I will also say about the RS bikes is they can be a handful to shift around in the garage or move by hand to put on lifts and such due to the very short, low handlebars.

If you don't want a fairing, the plain Jane bikes of those years are also fine bikes.

Unlike the modern BMW bikes all of the airheads are fairly easy to work on, even with the full fairings of the RS and RT, pretty much everything is accessible to work on with out always having to remove panels or fairing bits.

It is surprising how much gear can be carried by one of the old bikes, I find I can pack and strap almost as much gear as one of the newer GS bikes and more than the new RT bikes. LOL, the airheads also weight a lot less.

So that is my two cents of writing about the bikes, Kurt had filled you in as well as pointed you to Snowbum's site who will cover a lot more of the technical details.

I have said in other posts the airhead BMW bikes are the almost perfect motorcycle and there are people out there who have taken time and effort to bring them closer to perfection by some of the modifications and accessories on the market.

LOL, I say almost perfect, I mean for others, for me, they are perfect. My little RT does what I want the RS has more than enough power and handling for what I want and in my eyes is the most beautiful BMW ever made. St.

Hello Mal,

If you're interested in the handling ie hurrying through the bends, the later monolever type were the best handling of the airheads in my experience. Lighter flywheel, smaller front wheel made it a much more agile bike (the UK has a lot of bends). The /7s have a much more solid, ponderous feel and a heavier flywheel, so you set the bike up before the bend and power through. Horses for courses.

Charlie.

Thank you to all for your information and suggestions.

I am not sure, maybe /6 maybe /7.
To some extent I can't buy what is not available, so good to get ready by doing my homework.
It seems that in rebuilding my R90/6 after a crash in 1976, I preempted the /7 to some extent. See photo below.

Regards


Mal

The image is reversed for reason I dont know.

malmac wrote: ↑

Fri Jul 08, 2022 10:07 pm

The image is reversed for reason I dont know.

You're "down under"...that's why!

That is pretty nice. St.

schrader7032 wrote: ↑

Sat Jul 09, 2022 7:05 am

malmac wrote: ↑

Fri Jul 08, 2022 10:07 pm

The image is reversed for reason I dont know.

You're "down under"...that's why!

Yes you are right. Things down here are pretty strange.