1975 R90 new to forum

[hoodun]

I finally installed the pistons into the cylinders. At first it was a bit of a challenge when trying to install them with the pistons attached. Then I realized the only way I was going to do it was with a ring compressor and by removing the pistons.

[hoodun]

received the master cylinder rebuild kit.

I put a lot of time in to researching what to do about the brakes since I purchased a dual disk fork set, it would make sense to get a handlebar master cylinder. Though, since the single disk is a 14mm master cylinder and being that it is perfect size for a dual disk setup, I though I might as well try it. At least until I find a handlebar mc at a decent price.

I order stainless steel brake lines and will be ordering ferodo pads, since they are suppose to work best with the cast iron disks.

My slippers in the lower right corner of the last photo indicates how hard I've been working. They were near new when I started!

[hoodun]

I also received a new rotor, diode board, and regulator. the rotor tested bad and it was not much more to get the package deal which included the diode board and rotor. I sold the diode board on ebay which made me break even on the new diode board and regulator. Once I sell the regulator I should only be out about $80 for everything.

I also concocted some wires for the alternator to the diode board. Not because I didn't think the original wiring was not adequate, despite that some people feel this way. It was the fact that I cannot for the life of me find where I put the wiring. So I just create some new ones. I also added some grounds, since I painted the cover and was concerned that I would not get a good ground with the bolts, being that there is paint in the threads.

Also decided to stick with points after reading up on issues with the electronic ignition on these bikes. Plus I have been going in the purist direction, so I might as well stick to the 1970s engineering. New points and condenser added to the mix.

[hoodun]

finally starting to look like a bike again!

[hoodun]

new Swing arm bearings were installed along with new races and seals. the old races were pitted so everything was replaced.

the swingarm was centered by eye, checked with a micrometer. Then per snowbum, I torqued the bolts to 15 foot pounds and then backed off to 8 foot pounds. The 27mm locking bolt was torqued to 80 foot pounds.

[Kt-88]

This is a lucky airhead to find you.

[disston]

Very nice work. I like neat and clean.

The original points ignition will work just fine but you can also have the best of both Worlds by adding a Booster. This item will make the points last for several years instead of having to change them every year. I recently had to revert to the OEM ignition in the parking lot of a Mall but then I was running again and didn't have to call the tow truck.
.

[bmwblake]

i'm late to this party, but regarding the rings if you get bmw rings they come in an nice package noting which is which (an ABC designation) with a diagram of the piston showing where each goes. they also say 'top' on the top side of each.

[disston]

A word of caution about installing rings. Since you have the ring compressor that only works off the motor the pistons will have to protrude a bit on the bottom and the wrist pins installed. Working in this position is the problem You can't see a lot of what is happening at the same time as you are placing the parts. The wrist pins will go in when they are aligned perfectly and there are no burrs. It is always fumble time for me when I do it this way. But then comes a simple part of the operation that is more important than some realize. The circlip must be in place correctly. If one end is not in the grove once the motor is run later it can work it's way out. This happened to a friend of mine and he had a lot of expense saving his R100 motor including rebuilding the lower end of the motor because the metal had hit the oil pump and ruined most of it.

Installing circlips is a common mechanics operation. They fit in the grove. We have two different types, the wire ring type and the expansion type. From the pictures it looks like you have the wire type. No mater, with either type of circlip there is a part of the operation that needs to be mentioned. You should do this so you can sleep at night. After the circlip is in position it is "Proofed". With some sort of sharp pointy tool the circlip should be partially rotated in the grove. A circlip that is seated will rotate. If one end is not seated the circlip will pop out. Prove the circlips.

If you have this all together now maybe you can remember that they were properly seated. If not think about it before you run this motor.

[hoodun]

Originally Posted by disston

A word of caution about installing rings. Since you have the ring compressor that only works off the motor the pistons will have to protrude a bit on the bottom and the wrist pins installed. Working in this position is the problem You can't see a lot of what is happening at the same time as you are placing the parts. The wrist pins will go in when they are aligned perfectly and there are no burrs. It is always fumble time for me when I do it this way. But then comes a simple part of the operation that is more important than some realize. The circlip must be in place correctly. If one end is not in the grove once the motor is run later it can work it's way out. This happened to a friend of mine and he had a lot of expense saving his R100 motor including rebuilding the lower end of the motor because the metal had hit the oil pump and ruined most of it.

Installing circlips is a common mechanics operation. They fit in the grove. We have two different types, the wire ring type and the expansion type. From the pictures it looks like you have the wire type. No mater, with either type of circlip there is a part of the operation that needs to be mentioned. You should do this so you can sleep at night. After the circlip is in position it is "Proofed". With some sort of sharp pointy tool the circlip should be partially rotated in the grove. A circlip that is seated will rotate. If one end is not seated the circlip will pop out. Prove the circlips.

If you have this all together now maybe you can remember that they were properly seated. If not think about it before you run this motor.

Thanks. I double checked the circlips to make sure they were all the way in I did not tun them like you mentioned though.

One thing I neglected to do was oil the cylinders! They are bone dry. I do not have the valve covers on yet though I do have the heads torqued. I am debating on pulling the heads back off to put a small amount of oil on the cylinder walls. Or maybe I can just have the starter turn the engine with the plugs disconnected to get some oil in there. Any thoughts on this?

[hoodun]

I just checked out the photo gallery on here. Damn! Some absolutely amazing images! Kinda makes me want to convert my bike into a scrambler. ...next project?

Things are starting to come together. There is some light at the end of the tunnel.

I just coated the tank with red kote. The photo of the inside of the tank is after a quart of muratic acid with the tank filled with water. My process was citrus paint stripper, a soak in muraitic acid and water 20/1 let sit for 24hrs. more citrus paint stripper another soak of muriatic acid 20/1 and then acetone to dry it out. I manged to keep all chemicals off the paint by wrapping it in a tall kitchen bag. A 3mil bag would have been wiser though what I did worked for me, luckily. I used rubber bands on the petcock holes and a funnel on top to get all the chemicals in.

[disston]

The modern theory of running in new piston rings is to do it dry, cylinders honed. I forget the rpm recommended but when I did it I revved the engine up a bit so it sounded comfortable. Maybe that was 3,000 rpm. Maybe I did more. I don't remember.

The idea is to bed the rings faster than how we did it years ago when we oiled the rings and had to run engines in for several hundred miles at various rpms.

I think you can find info on this on Mr. Snowbum's site.

[hoodun]

I'm starting to see some light come through this dingy dark garage. Finally got her started up after eight months! Starts right up with no adjusting.

Still needs timing/ valve/ carb adjusting, front brakes, seat cover attached, new throttle cables, a couple bolts, exhaust flanges tightened.

http://www.youtube.com/watch?v=uef74lyrbhk&feature=youtu.be

[disston]

The linky didn't work for me.

[hoodun]

Originally Posted by disston

The linky didn't work for me.

It should work now.