getting the background info on the /7 bikes

[srankin]

Where are you in relation to Melbourne? I have a pen pal there who is a long time expert on the R90S bikes and BMW in particular. St.

[schrader7032]

Where are you in relation to Melbourne? I have a pen pal there who is a long time expert on the R90S bikes and BMW in particular. St.

Toowoomba (where Mal is) and Melbourne are over 16 hours driving distance apart!

[malmac]

Where are you in relation to Melbourne? I have a pen pal there who is a long time expert on the R90S bikes and BMW in particular. St.

Toowoomba (where Mal is) and Melbourne are over 16 hours driving distance apart!

Kurt

Was that you looking through our front window?

Just kidding. You seem to know Australia pretty well.

And you are right, Melbourne is a long way down the track. So far in fact that we refer to them as Mexicans, us cane toads from the North.

Cheers Mal

[malmac]

Where are you in relation to Melbourne? I have a pen pal there who is a long time expert on the R90S bikes and BMW in particular. St.

Thank you for your thoughts. Much appreciated.

Regards


Mal

[srankin]

The internet sometimes is a good thing. Miles apart but seconds from communicating. St

[Werner1111]

Mal - what a fun choice! It would be hard for me. I've had two /6s and three /7s and still have three of those bikes.

When you say /7, are you speaking in a strict sense meaning that you're only thinking about '77-'78 or do you mean the whole run from '77 to '95? (Edit - I missed that you said through 1979 in my first read)

This link is to tons of downloadable PDF BMW brochures from the 1970s, mostly /7.
I know what you'll be doing for the next many hours.http://www.omnilex.com/public/bmw78/

Everyone before me on this thread already did a wonderful job. I can think of a few more little things from the 74-'80 era. 'The monolever era is a different ball of wax and I don't have any experience there. The 1977 is the last year with an on/off switch for the headlight, the 1978 does not have one (always on). 1979 is the last year with the aluminum airbox, after that, they have the black plastic airbox. The different flywheel/clutch setup started in 81, I think. Maybe 80. As mentioned, somewhere during 1978, they stopped putting spoke wheels on the /7, but you can retrofit if you like (like I did on my '78's). The '77 headlight shell is gloss (or semigloss) black and the '78 is matte with an orange peel type of finish. I prefer '77. The '77 wrist pins are held in with snap rings that fit into a groove (PITA). The '78 has a circlip that can be removed with circlip pliers. When I rebuilt the top end of my R100/7, I put R100RS carbs and top end on the bike to get a little extra oomph.

According to Oak (Airhead Tech Advisor for many years), the '74 transmission isn't the best. The '74 /6 has the aluminum turn signal bodies and handlebar switch gear from the /5. The '75 and '76 handlebar switchgear and turn signals were updated and is very similar to the /7, though not the same. For awhile, you could only get replacement /7 switchgear from the dealer but perhaps you can get /6 switchgear now. You can retrofit the /7 switchgear to the /6. I don't think there is too much difference between the '75 and '76. I think '75 has black calipers and '76 has silver.

The /6 and /7 seats are different to accommodate the different lengths of the /6 vs. /7 tanks. The frames are mostly the same, other than gusseting, etc...

Á copy of Ian Falloons Boxer Twins Bible https://www.amazon.com/BMW-Boxer-Twins- ... 184584999X could be helpful as it has much of the info you want. But they're hard to find at a reasonable price anymore. There is a Kindle version for $30.

I think at the end of the day, the main difference is cosmetic. Do you like the /6 tanks (there are two) or the /7 tank? and even that stuff can be swapped around, along with the valve covers.

One other consideration is the GS model. On my short list is the R100GS/PD in Red/White. It's a beautiful bike and will take you on a different set of adventures. I've been thinking about making a change from my R1150GSA.

[Werner1111]

After walking away, things started to come back to me. I restored a 1978 R100/7, modded a 1978 R100S, and brought a 1976 R90/6 back to life, so I have spent (too much!) time looking at the details. I also had a first year blue 1977 R100RS and got into an accident with a car (her bloody fault) after searching for one for 6 months and then having ridden it for only 18 miles before the accident two blocks from my house. It was totaled and I bought it back from the insurance company and parted it out. That was awful.

On the /6 ('74-76), the 1974, '75 and early 76 rocker blocks are not indexed to the head. The mid-'76 and later into the /7s have a boss on the head to position the rocker blocks. There is a method to line things up on the earlier models. "Oak" Okelshen published a "Boxer Top End Manual", which is an invaluable reference, and covers how to do this procedure. I believe his widow is still selling copies for something like $20. Lining things up is important because it ensures that the pushrod does not rub in its tube and also so that the tip of the rocker arm hits the valve stem correctly causing a little valve rotation with each stroke.

The R90/6 and R75/6 have Bing CV carbs, but the R90s has Dell Orto 38mm slide carbs, which were a significant improvement in performance. I see that you had a R90S tank on your R90/6, by the gas cap protruding from the top. The /7 tank is almost the same as the /6 S tank, but the /7 gas cap is recessed in the tank. Also, the S had dual front discs.

If you get a /6, my first choice would be a '76, but the '75's are almost equally as good. The /6 bikes came in beautiful, racetrack inspired colors like Nurburg Green, Bol d'Or Red, Daytona Orange (R90S), and Monza Blue.

Regarding the /7, the S and RS have some performance improvements over the standard R100/7 including dual front disc brakes, 9.5:1 compression (vs 9.0), and 40mm Bing CV carbs (vs. 32mm). They also have holes in the aluminum airbox to breathe in more air. The RS (and S?) initially came with a 40mm exhaust, while the rest of the lineup came with a 38mm exhaust. However, due to certain new regs in the US, there are RS (and S?) bikes out there starting in 1977 (probably mostly in the US) with CFO stamped next to the oil dipstick location, meaning "California, Florida, Oregon". These bikes have a 38mm exhaust diameter to comply with the regs in the aforementioned states. Eventually, all the bikes had 38mm exhausts. In my experience, it is rare to find one with a 40mm exhaust.

Personally, I think the 1977 R100S is the bike to get in that era, assuming it fits your taste/needs. Everyone fawns all over the R90S, but the R100S has a little more horsepower and looks almost identical, except for the paintjob and the gas cap sticking out of the top of the R90S tank. A friend of mine bought an R100S new in Germany while stationed there in 1977, but had the dealer swap out the painted parts with the silver R90S paint job. Bingo. Prices for the R100S are nowhere near those of the R90S, less than half. The original R100S paint scheme of starburst red on black is quite pretty too. In 1978, there was also a Motorsport White edition and the word is these were leftover R100RS Motorsport editions with S fairings. If you don't like the S fairing, take it off and keep the extra horsepower and braking. Well, it also has an S seat too.

As you'll see in the brochures linked in my prior post, the '77 and '78 colors were also very nice. I have the orange R100/7 which is really striking in the sun, but looks like brown in the shade. I also drool every time I see the gold 1978 R100RS. You probably either love it or hate it.

[malmac]

After walking away, things started to come back to me. I restored a 1978 R100/7, modded a 1978 R100S, and brought a 1976 R90/6 back to life, so I have spent (too much!) time looking at the details. I also had a first year blue 1977 R100RS and got into an accident with a car (her bloody fault) after searching for one for 6 months and then having ridden it for only 18 miles before the accident two blocks from my house. It was totaled and I bought it back from the insurance company and parted it out. That was awful.

On the /6 ('74-76), the 1974, '75 and early 76 rocker blocks are not indexed to the head. The mid-'76 and later into the /7s have a boss on the head to position the rocker blocks. There is a method to line things up on the earlier models. "Oak" Okelshen published a "Boxer Top End Manual", which is an invaluable reference, and covers how to do this procedure. I believe his widow is still selling copies for something like $20. Lining things up is important because it ensures that the pushrod does not rub in its tube and also so that the tip of the rocker arm hits the valve stem correctly causing a little valve rotation with each stroke.

The R90/6 and R75/6 have Bing CV carbs, but the R90s has Dell Orto 38mm slide carbs, which were a significant improvement in performance. I see that you had a R90S tank on your R90/6, by the gas cap protruding from the top. The /7 tank is almost the same as the /6 S tank, but the /7 gas cap is recessed in the tank. Also, the S had dual front discs.

If you get a /6, my first choice would be a '76, but the '75's are almost equally as good. The /6 bikes came in beautiful, racetrack inspired colors like Nurburg Green, Bol d'Or Red, Daytona Orange (R90S), and Monza Blue.

Regarding the /7, the S and RS have some performance improvements over the standard R100/7 including dual front disc brakes, 9.5:1 compression (vs 9.0), and 40mm Bing CV carbs (vs. 32mm). They also have holes in the aluminum airbox to breathe in more air. The RS (and S?) initially came with a 40mm exhaust, while the rest of the lineup came with a 38mm exhaust. However, due to certain new regs in the US, there are RS (and S?) bikes out there starting in 1977 (probably mostly in the US) with CFO stamped next to the oil dipstick location, meaning "California, Florida, Oregon". These bikes have a 38mm exhaust diameter to comply with the regs in the aforementioned states. Eventually, all the bikes had 38mm exhausts. In my experience, it is rare to find one with a 40mm exhaust.

Personally, I think the 1977 R100S is the bike to get in that era, assuming it fits your taste/needs. Everyone fawns all over the R90S, but the R100S has a little more horsepower and looks almost identical, except for the paintjob and the gas cap sticking out of the top of the R90S tank. A friend of mine bought an R100S new in Germany while stationed there in 1977, but had the dealer swap out the painted parts with the silver R90S paint job. Bingo. Prices for the R100S are nowhere near those of the R90S, less than half. The original R100S paint scheme of starburst red on black is quite pretty too. In 1978, there was also a Motorsport White edition and the word is these were leftover R100RS Motorsport editions with S fairings. If you don't like the S fairing, take it off and keep the extra horsepower and braking. Well, it also has an S seat too.

As you'll see in the brochures linked in my prior post, the '77 and '78 colors were also very nice. I have the orange R100/7 which is really striking in the sun, but looks like brown in the shade. I also drool every time I see the gold 1978 R100RS. You probably either love it or hate it.

Thank you for taking the time to share your extensive experience and knowledge.

I am not interested in a few extra horsepower...... if I was I would buy a new bike with 150HP or more.
I really like the 1974 and then the 75/76 models are good and the 77/78 models seem good as well. Certainly not going to a plastic air box etc.

It might make sense if I say my other bike is an R69s.... so I like the older aesthetics, rather than the newer.
While our R1200GSA has been a great bike in lots of ways, I dont much like the transformer pieced together masculine aggressive aesthetics - I rather prefer smooth lines and a more feminine aesthetic.

Thanks again for your contribution to the thread, it is much appreciated.


Regards


Mal

[Werner1111]

Thank you for taking the time to share your extensive experience and knowledge.

I am not interested in a few extra horsepower...... if I was I would buy a new bike with 150HP or more.
I really like the 1974 and then the 75/76 models are good and the 77/78 models seem good as well. Certainly not going to a plastic air box etc.

My pleasure. I've got plenty in my head that I'll eventually forget, so I'm happy to get it out now while it's there. I am familiar with your R69S and hear you regarding aesthetic, and HP. An extra 5 hp is not that big of a deal when you can get double in a newer model. I really like the /6 with the larger tank, aesthetically.

The '74 has some of the charm of the /5 (aluminum turn signals and handlebar switches). Transmissions can be rebuilt. That's really my only reason to put it at the bottom of the /6 list. Why did you draw the line at /5?

[srankin]

If you like the smooth lines and practical, the RS and RT bikes are the way to go. As I said, I have alway felt the RS bikes to be the prettiest bike BMW ever built and after riding in wet weather more than a few times I can attest to the weather protection of the RS and RT fairings, plus the stability in windy weather. Now in hot climates, I think I would and may still one day pick up a naked bike or a S fairing bike. I did have two R90S bikes at one time that were projects that I lost interest in and sold. The prices of R90S bikes keep me on the edge of buying one now.

Personally the best bike BMW made was the 77 78 and 79 RS. The only drawback to a wonderful bike is the crouched over riding position due to the low short handle bars. They can be a pain in the ass to move around on a lift, in a garage or parking lot.

The GS bikes are great for hauling stuff but to be honest I can haul the same amount of gear on my RS or RT. The only draw back to the RS and RT is the pretty fairings. I used to ride on gravel and dirt roads for the first years of my RT ownership and ended up having to have the fairing repainted due to it looking like someone peppered it with a shotgun due to stone chipping. The GS bikes don't really have this problem to the dame extent, LOL that is the kind of roads they were designed for.
All of the pre 95 BMW bikes have something going for them. If I had the space, I would fill it with one of each, /2, /5/. /6. and /7. St.