6 replies [Last post]
JohnV's picture
Joined: 10/15/2015
Posts: 1

Hi all, Im a first time airhead owner. Just recently bought an 75' R90/6 last week with hopes to take it on a pretty far trip this spring.
The current plan is to go South from Chicago to Lousianna, West through texas to the Grand Canyon and Vegas. The to San Fransico, up the pacific coast highway. Then towards colorado, Kansas City, and finally back to Illinois. Needless to say there are several things i need to do in order to prepare for this trip and i thought this would be the best place to get some real advice.

The bike i bought was a 1 owner bike with the original title. Bought it from an old man who was really reluctant to sell it but felt bad that it sat in the garage unridden since he physically cant ride anymore. He came around when he knew what my intentions were with it. The bike is in overall good condition i think. I've taken it on a few hour long rides and it has faired just ok. It has a few issues, some of which definitely need need to be addressed before a long trip.

1, The odometer is not functioning, The man said it went out 10 years ago, and claimed the bike probably had between 75-100k miles on it. Which from what i read doesn't seem like a huge number or concern for a bike that old.

2. The Kill switch is not functioning,

3. The throttle is a little tight and hurts my wrist after any significant riding time.

4. The clutch is also very tight and hurts my wrist/forearm

6. The Shift return spring is not working. I hope this makes sense but, the bike shifts fine up, however, when downshifting, the shifter does not return back to the neutral position. So from 3rd to 2nd, after downshifting to 2nd, to then downshift to 1st, requires me to sort of pick up the shifter with my foot back to the neutral position (being careful not to kick it into third), so that i can then downshift further to 1st gear. Is this super important to fix? is it expensive? It seems like more of an inconvenience than anything. If i am going to open up the transmission to fix the shifter return spring would it be worth it to do a entire rebuild?

5. The carbs need cleaned. -- The man said it probably was 10 years since he went through the carbs. When he pulled the bike out of the shed it started up and has been starting up for me easily over the last month. However, sometimes she has a hard time idling and sputters occasionally. Also, She doesn't seem to want to go above about 70 mpg, Which is ok for country cruising, but on a trip like this i think i would need more power to get over mountains and in higher altitudes. Will the carb cleaning help fix this last of power? What else can i do to increase the power?

I have a little experience with motorcycles, I've done regular maintenance on my 03' Honda Shadow for the 3 years i've owned it and worked on a few smaller Honda CBs fixing them up and selling them. All my knowledge comes from self teaching and youtube videos. Everything I've read about 40 year old beemers is that if you're inexperienced you really should have a professional do the work. Any opinions on this? Really nervous to try and open up the carbs myself, especially considering i live on campus in an apartment and do not really have a working garage and tools available to me

Also, If im going to be going on this trip, What other spare parts, tools, emergency anythings, that i should bring with me? Or any other suggestions, tips, anything would be appreciated. Hoping you guys can teach me a lot!


John from Illinois,
75' R90/6

Darryl.Richman's picture
VBMWMO #6285
Surf City, USA (Santa Cruz, CA)
Joined: 10/27/2006
Posts: 2185
Some of these items don't

Some of these items don't sound like they might be cheap to fix. As you're in Chicago, you should look up the Chicago Region BMW Owners Assoc. (www.crbmw.com), as they have a lot of tech events and you can find help for your bike locally. You don't need to have a professional do the work, if you're inspired to do it yourself and can get the information you need to do the job right.

A nonfunctional odometer is not unusual. The typical problem is that the number wheels are held by a pressed on part that eventually comes loose, and the wheels spin randomly. If the speedometer shows the right speed and the needle doesn't bounce, this may be your only problem in this area. The wheels can be fixed, either by you, by someone locally with experience or at a speedometer shop.

The dead kill switch might require a new control pod.

Your carbs might need new diaphragms if they seem to work at lower RPMs but can't get the motor to run at higher speeds. However, this could also be a problem with worn ignition parts: points, condenser. An R90/6 should easily do 100+mph.

The throttle shouldn't be tight, it should operate smoothly and with fairly light force. You may need new cables (could help your clutch, too) and/or greasing the throttle gears inside the handlebar unit.

Check the brake fluid in the reservoir under the tank! Replace the tubes and tires if you still have the ones that were on it when you bought it.

The transmission may have a weak or bent pawl spring. The spring is not expensive, but getting into the transmission could be. This is one area that calls out for someone with experience.


VBMWMO Webmaster,--Darryl Richman

schrader7032's picture
VBMWMO #7032
San Antonio, TX
Joined: 10/27/2006
Posts: 6710
Some sites showing carb

Some sites showing carb rebuilds:


As for the speedo, Darryl mentions the random numbers. This shows how to fix that:


It's for the /7 but should be essentially the same.


Kurt in S.A.
'78 R100/7 '69 R69S '52 R25/2

clayton's picture
Joined: 09/16/2015
Posts: 14
If you decide to rebuild the

If you decide to rebuild the carbs yourself I recommend the following:


I used his pictorial guide to rebuild the carbs on my R75/5 and it was fairly straight forward.

Good luck to ya.

mark_weiss's picture
Joined: 11/16/2013
Posts: 173
Something may be binding in

Something may be binding in your gearshift mechanism. There is a single spring that re-centers the gearshift lever after each shift, up or down. Is the fifth to fourth shift OK?



pokie's picture
Joined: 02/08/2015
Posts: 118
Tight Throttle

Hi, when you say the throttle is tight, explain. Is the throttle hard to turn, is it difficult to hold the throttle in one position? If it is difficult to turn, will it hold position once you get it turned?

If the throttle is hard to turn, it could be dry or bad cables. If the throttle is difficult to turn but holds it's position once turned, again it could be bad cables OR it could be that the throttle tube is binding on the handle bars OR it could be that the bike has fallen over and the throttle unit got jammed further onto the bar than it's supposed to be, causing the grip to drag on the end of the handle bar. If the throttle turns ok but is just too strong to hold for long, it may just be that the carburetor springs or throttle return springs are just too strong and either need to be stretched or replaced with lighter ones. If your throttle has a damper screw (underneath), it may be too tight. Something to remember, your throttle grip will never snap back, at best it will creep back. If your throttle grip returns to the start position when you let go of it, this is a sign that the gears aren't greased properly or that the return springs are too stiff.

A good place to start is to open up the throttle top and grease the gears in there as well as making sure the throttle tube or twist grip hasn't got a bunch of filth inside causing the tube to bind. This is also a good place to add grease. What I used to like to do (still do it) is to remove the screw in the top of the throttle unit and pump grease into it until it oozes out the sides of the throttle cover. This not only greases the gears inside but also forces grease into the area between the throttle tube and the handle bars. Some folks don't like doing this as it also allows grease to go down the throttle cables.

Once the throttle is working properly and greased properly, if you are still having wrist fatigue, you might consider a throttle rocker or the like to assist in keeping the throttle held. You could also experiment with the stock throttle damper screw on the bottom side of the control unit.

pokie's picture
Joined: 02/08/2015
Posts: 118
Shift lever return

You stated that your shift lever won't return when you are shifting down. Does it return properly while shifting up or is it returning but kind of wimpy?

If the lever is returning positively while shifting up, the shifter pedal shaft may be bent or misaligned. To check for this, loosen the shift pedal (don't totally remove the screw, only loosen it). Try shifting with it loosened, is the pedal returning fine? If it is now returning just fine, try tightening it again. If it again starts to misbehave, you may have a bent shift lever shaft or just a bent retaining bolt. If, when loosened, the shifter still won't return properly, then as Darryl says, the shift return spring is likely broken. In this case you have to decide if you want to put up with the shifting problem or have it fixed. If you aren't familiar with BMW transmissions, you need to consult a professional. Again, as Darryl says, the return spring is relatively inexpensive but putting it in will be around $400 (this is just a guess). If it is discovered there are other problems inside the transmission, the price goes up.

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