Buying advice for guy returning to BMWs - R75/6

[Porge]

Sorry Duane, autocorrect on the iPad.

I'm all for the rolling restoration of this. I've let the oldest boy know of the bike, and he's pushing for camping trip on the bike. The price isn't too bad - I guess if you we're paying for everything to be done, it'd probably work out similar to a straight buy, but where's the fun in that?

[Rob]

Sorry Duane, autocorrect on the iPad.

Oh Podge, you have NO idea how sorry you are! ( )

Here, let me help you out...
http://w6rec.com/duane/opinion/halloween2004/index.htm

[Porge]

Wow!

[Porge]

Wow!

[Rob]

Yes, that was worthy of a 2nd post.

[Porge]

Okay - had a good look. The registration papers say it's a 75 model. Looks straight, if not a tiny bit unloved. Master cylinder was seized - likely at the pivot point, and freed with some WD40 and a gentle tap with a rubber mallet. Has leaked some fluid onto the frame, so a clean up there.

Some electrical gremlin that the owner is looking into - when he turns the ignition on, the horn starts blaring. Cranks, but no decent battery nearby. No real lash in the drive train. All gears select. Tank clean, and in good shape. Seat has a cover with it, and will need a little patching work on the base near the rear mount. My brother in law is a welder by trade . Chrome good, and the luggage is excellent. Has a craven top box as well. Most tools present, has a starter motor spare, and a genuine diaphragm set. And an aftermarket set as well, so am planning a carb strip and rebuild, I guess.

The deal makes it still cheap considering the asking price of other /6/7 bikes I've seen even when taking some work into account, and I like the /6, so It's coming home with me tomorrow

[Ken in Oklahoma]

Okay - had a good look. The registration papers say it's a 75 model. Looks straight, if not a tiny bit unloved. Master cylinder was seized - likely at the pivot point, and freed with some WD40 and a gentle tap with a rubber mallet. Has leaked some fluid onto the frame, so a clean up there.

Porge, until you get into the master cylinder may I suggest that you lower your hope/expectations on it a bit. As for the leak onto the top frame tube, "they all do that sir". my '76 R75/6, my '77 R100/7, and my '77 R100S, have all leaked at some time and screwed up the paint. But do be alert to other problems. That leaked brake fluid has a habit of somehow getting onto various electrical connections and corroding them and 'munging' them up. A typical symptom will be something electrical works sometime and sometimes it doesn't. This can be maddening. There's quite a few connectors and connections under the tank. You might want to look at all connections and brighten them up as best you can with contact cleaner and a bristle brush, perhaps like an old toothbrush.

The master cylinder is easy enough to take apart. You will want to do that and inspect it carefully. Especially look at the rear part of the bore at the bottom. That's where any water in the brake fluid will collect. And often you will see pits where the metal has been rusted away. This is commonly what caused the master cylinder to leak in the first place. I have honed out the bore using fine wet or dry sandpaper and a soapy water solution. But you are removing a bit of metal making the piston seal and rear seal more prone to leakage.

When you decide you need a new master cylinder kit, beware that they are very spendy. It's been years since I've bought them and I doubt the price has gone down.

However yours may be in fine shape and a little honing will make it as good as new.

Airbear's R75/6 is one of the earlier ones with the 'old style' switchgear. Yours, hopefully will be the same. That makes a changeover to a handlebar mounted master cylinder easier and cheaper to do. I believe the new handlebar switchgear made it's advent in model year 1976. That in part is why I'm still running my '76 with the old under tank master cylinder. I haven't ridden that bike lately but when I put it on the road again I expect to be ponying up the money for a handlebar mounted master cylinder.

You're going to love your R75/6. Interestingly less power than the larger engines can be more fun. I have taken a couple fast (for me) rides on it around the 'Lowman Loop' north of Boise. To stay up with the pack I had to 'wring the bike's neck'. That put me in the RPM range where these airheads really sing and it forced me to pay a lot more attention to what gear I was in.

Ken

[Airbear]

...

When you decide you need a new master cylinder kit, beware that they are very spendy. It's been years since I've bought them and I doubt the price has gone down.

However yours may be in fine shape and a little honing will make it as good as new.

Airbear's R75/6 is one of the earlier ones with the 'old style' switchgear. Yours, hopefully will be the same. That makes a changeover to a handlebar mounted master cylinder easier and cheaper to do. I believe the new handlebar switchgear made it's advent in model year 1976. That in part is why I'm still running my '76 with the old under tank master cylinder. I haven't ridden that bike lately but when I put it on the road again I expect to be ponying up the money for a handlebar mounted master cylinder.
...

Ken

The last time I looked, the master cylinder kit was $190 for a surprisingly small package of bits.
Porge, if yours has the earlier /5 handlebar controls a bar-mounted aftermarket MC will be cheaper and increase your braking performance dramatically. See here: viewtopic.php?f=1&t=5461&hilit=Magura

If yours has the coloured plastic switches on the handlebar perches the story is different. You will need to look for a later model bar-mounted MC.

Re the horn blasting with ignition on, the horn button completes the circuit by connecting to ground. Fault could be in the left hand perch switch, headlight bucket or between the bucket and under the tank.

Congrats on making the decision to buy. You are in for a treat. These bikes are a joy to work on and huge fun to ride.

[daz]

One good thing about the whole situation is that since Duane is moving and he did not offer to look over your bike if you sent it to Gault for six months or a year. Thank your lucky stars. He is one generous individual.

[Porge]

Cheers Airbear,

I've got the later style switchgear, with the kill/indicators on the switchblock. Well see what'll work