R65 barn find

[Bill Conquest]

Hi..I just acquired A 79 r65  that had sat for 10 years and taken apart .. I managed to get it all together and .. it’s running !!  The only problem is the front disc brake system is shot and I can’t find a master cylinder .. i’ve had bad luck in the past with rebuild kits and would like to get a new complete master cylinder .. anybody know where to look ? I’ve checked pretty much everywhere I can think .
 Thanks in advance
Bill

[Matt Chapter]

Your '79 will have had the round master cylinder, I believe.  It's NLA.  I think I've heard that the newer design rectangle will fit, but someone else might be able to verify.  You probably also have the early caliper design, can't remember the name, but the pistons are also NLA and likely to be corroded beyond saving.  Later iterations of the R65 have Brembo calipers.

Likely you will not be able to go back with original matching equipment, and you'll want to investigate switching to slightly newer brembos, and a suitable master cylinder to drive them.

I also believe the '79 is a single disc, once configured correctly this will probably be capable of stopping the bike reasonably.

[BPT]

The calipers before Brembo were Ate, correct?

[Barry]

Original caliper on a 79 would have been an Ate and yes you will be much better off with a Brembo. Seals and dust caps  are available for the Ate but thay are quite expensive. The original master cylinder will have been 13mm for a single disc. The size used with the rectangular version was 12mm so don't expect to find a 13mm replacement. I wouldn't be looking for one anyway as the 12mm size was an improvement. Some have gone even smaller at the risk of excessive brake lever travel.

[Tony Smith]

The later "square" master cylinder will fit the 1979 handlebar "perch". But, you will also need the 81 on brake lever. If you  are staying with a single disc I would buy a new Brembo/Grimeca caliper and I would get the 12mm master cylinder. The ATE caliper can be rebuilt, but at commercial rates will cost the same or more than a new replacement. Motobins has all the parts you need.

[tiggum]

I have the brake lever from the original M/C (since replaced) on my 1983 R65LS, if it is needed.  You may have it for the cost of the postage.  If interested, send me a PM with address.

Tiggum

[Tony Smith]

One thing I forgot, the 1979 will have a pressure switch in the brake line - these rarely survive being left long term with old fluid in the line. If you need a new one they are readily replaceable at any good automotive store, they are a standard thread size - I cannot recall whether they are a "straight" thread or a tapered thread, but that will be obvious when you pull the old one out.


I recomend staying with the pressure switch as they are cheaper and more reliable than the perch mounted mechanical switch (*and depending on just how early your 79 is, you may not even have the mount for a mechanical switch.

[Bill Conquest]

 Thanks everyone for all the great input .. I have to go over all this information and figure out which way to go .
 I did find an original round master cylinder ..new ..quite expensive .. and some stainless steel lines . I’ve got to check out the pressure switch that Tony mentioned as I haven’t seen it  anywhere . As for the calipers I’m not sure they don’t look too bad but I haven’t checked them out yet ..
 Meanwhile the bike runs pretty well except for the odometer not working ..
Many thanks for all the help
Bill

[Barry]

Pressure switch should be on a manuifold behind the headlight.

[Bill Conquest]

Right.. there it is!.. any thoughts on repairing the odometer ?

[Barry]

The odometer has a common problem with a gear slipping on the shaft.
Mine does it a little but only when the bike has been stood in hot sun all day.

If you go back to mid June on this same board, there is a thread started on the slipping gear.

[ged in oz]

Hi Bill, here is the link to the thread that Barry has mentioned above:

http://www.bmwr65.org/YaBB2.612/cgi-bin/yabb2/YaBB.pl?num=1557823481

If you scroll down through the thread long enough you will find another link that takes you an article that explains the procedure. It’s on an R100 clock, so access is different but the internals are the same.

You need to uncrimp the face of the R65 clock to get into it, but it’s very soft material so it’s easy enough to do. I got a small screwdriver blade under the crimp and then gently worked it around without distorting it too much.

You live in a very beautiful part of the World! I spent a few days in Kauai about 15 years ago. Breathtakingly beautiful.

[Bill Conquest]

 Hey thanks a lot you guys ... i’ll check that thread and see if I can do it .
 Yeah this is a beautiful island thanks
Got to be a little careful riding ..tourists tend to not look where they’re going too well  because they’re distracted by the nice scenery .. can’t blame them [ch127752]

[Bill Conquest]

 Well I finally received my master cylinder and Yep .. wrong one . After getting it straightened out with the vendor I received the retro new one .. The rectangular one with a new  lever and throttle top assembly  i’m now waiting for the stainless steel cables to arrive .. and then I’ll find out if the caliper is any good . If not I guess I’ll have to switch to a brembo, in which case I’ll be requesting information here ..( thanks for the offer tiggum.. they sent the whole thing as a package seemed a lot easier to go that way ).
 Thanks everyone for the help I’ll keep you updated
Bill

[Bill Conquest]

Hi all.. A question regarding my barn find 79 r65.. I acquired this bike pretty much taken apart and I reassembled it including the wiring harness .. it started and ran pretty well for a little while then had absolutely no spark. I started looking for loose wires etc. also checked the points but then discovered that I had misswired the coil in front, according to my Haynes manual. The manual shows the points  wire at contact 1 and the blk/yellow at contact 15.. going back to contact number 1 on the back coil..Also a black wire on contact 1  to the tachometer I think it is .
 I had the points  wire and the black and yellow wire reversed . After correcting it I got a good spark and the bike starts .
 My question is why did it start when it was backwards and run for a while and then suddenly die ..
 On a different note I just got all my brake parts together and will be assembling them shortly hopefully the caliper will be OK .
 Any thoughts regarding the coil question would be much appreciated .
Thanks
..Bill