The /5 tank will fit on the /6, but you will have to re-locate the front brake master cylinder. There will be some considerable expense involved in that.

Thanks James. Can you or anyone else explain the process to do this? Although I am a noob I did own a 1974 75/6 years ago and did most of the work on it.
I never did any brake relocation work.

You would need to acquire a throttle assembly hand set and master cylinder, appropriate brake line(s), and a switch for the brake light circuit. I I remember correctly, Tom Cutter or Anton Largadier can set you up with the whole package.

You will need the throttle side hand set, a corresponding master cylinder, brake line(s), and the switch for the brake light. If I remember correctly, Tom Cutter or Anton Largadier can put together a package with everything you would need.

Hi everybody. I'm fairly new to this forum, but not to motorcycles or motorcycle forums in general. This is my first "trial balloon post" on here to figure out how things work, like quoting, posting pictures, making an avatar, etc. Don't take anything too seriously -- this is a test. This is only a test. B)

I am a noob and just started restoring a 1974 R90/6. I already have a checklist of items to work on before starting the bike. The original tank is shot. I have a large tank from an early /5 that does not have the extra space for the under tank front brake master cylinder (MC) for the /6. Will the /5 tank fit on my /6 if MC is removed? Can I mount the MC on handlebar like the /7?

Do you really want to use /7 handlebar controls on your 1974 R90/6 motorcycle, so that you can strip off the UTMC and fit a /5 fuel tank? If so, that's cool and you could do it. Just be aware that you would be customizing or renovating your motorcycle, and certainly not restoring it. To restore a motorcycle means to return it as closely as possible to original condition.

If you sold the /5 fuel tank to somebody who wants to restore a /5 machine, and then you used the proceeds to buy a real /6 fuel tank, you could restore your 1974 R90/6. That would save you a lot of work and probably some money in the process. Your bike is the only year of the /6 that has the nice, rebuildable /5 handlebar controls carried over from the previous model. They look good and are intuitive to use. It would be a shame to lose them. Properly reworked, the UTMC setup works just fine.

I'm not preaching here, just offering an alternative idea. I have a 1974 R90/6 that I rebuilt. I can't say that I restored it, because I used powder coat, changed to stainless steel spokes, updated the starter relay and voltage regulator, put on some aftermarket silencers (used), etc. I guess mine is renovated.

Some "before & after" pictures:

By the way, redbaron, although the tank and side covers on my bike are still in their original paint, they are not original to this bike. The tank came from an R75/6. I do still have the under tank master cylinder setup.

Ray

Hey Ray, Thanks for confirming the /5 tank will work on my /6 and that the /7 MC will work on the /6. Thanks for your input.

/7's were originally fitted with under tank master cylinders. The earliest handle bar master cylinder that I know of was fitted on a 1981 R100.

Well, I misspoke on my very first post on here, and actually did know better. Thanks, James for the correction. 😳

redbaron, look HERE for Anton's page showing when BMW first moved the master cylinder to the handlebars.

Also, some people have modified their 1974 R90/6 to move the master cylinder to the handlebar and yet retain their original switch gear. There is a thread that discusses this on the advrider.com airhead forum. Click HERE. You can still read that thread, but photobucket has destroyed most of the pictures.

Although it is only for the 1976 through 1980 airheads, Moto-bins in the UK has a kit for converting from under the tank to the handlebar mounted master cylinder. That kit costs US $455, to give you an idea of what's involved.

Anton Largiader would be a good resource. On the MOA forum, he was asked about converting a /7 master cylinder to the handlebars and replied that he does that all the time. Click HERE. He told the guy to contact him. I am sure he could fill you in on the best way to go with your '74 R90/6 as well.

Ray

Tanks again and I should have mentioned that I contacted Anton after James gave me his name. He has been extremely helpful and will be sending me the conversion components. Peace