Bringing 74 R90S back to life after sitting 30 years

[_cy_]

thanks for all the help everyone!

this just came up in an oil thread about BMW saying not to use too thick of oil in final drive.
is 75W-140 too thick for final drive and drive shaft?

I'm confused... some say to use 75W-140 in airheads, some say 90W per BMW's spec
http://bavarianmotorcycleworkshop.co...mw-motorcycles

[wirewrkr]

I just use the called for GL5 80/90wt.
No need to go high tech, the bike isn't..

[spo123]

In my /5, I have run Royal Purple 75/140, for the past 25,000 miles....transmission, final drive and drive shaft.
I may switch to the "thinner" grade for this winter...
spo


Edit> 9/2012.....now at 56,000 miles for the 75/140....summer and winter. Let transmission WARM UP before hard running and shifting.

[supershaft]

I have run Valvoline 80/90 for just under 250,000 miles. At least half of those miles have been ridden like no else I have ever seen do on an airhead street bike. Most people say because I am nuts! I like to think it is because I like a challenge. Great gear oil!

[_cy_]

Originally Posted by supershaft

I have run Valvoline 80/90 for just under 250,000 miles.!

is that dino or synthetic? seems a lot of folks prefer running dino on FD and shaft

here's the first pic taken with Nikon D2H

[supershaft]

Dino. Why in the world would you run dino in your FD and synthetic in your tranny? Proof that that some people are nuts!

[wirewrkr]

It's rare to see an original 1 year only seat fabric that is in one piece!
WOW!

[gplane]

Originally Posted by wirewrkr

It's rare to see an original 1 year only seat fabric that is in one piece!
WOW!

That bike is a dandy.
The non vented rotars, aluminum signal housings, /5-style controls.
The big changes in early 75 models?
If you bring her up-to-snuff, that's gonna be a nice ride,
When you crack open those Dellortos at about 4400 the sound is something you won't forget anytime soon.
The kicker is the kicker,
Here's to a nice S bike.

[danedg]

Originally Posted by _cy_

is that dino or synthetic? seems a lot of folks prefer running dino on FD and shaft

here's the first pic taken with Nikon D2H

Ur gonna die....

[_cy_]

here's why no fire ... condenser wire broken
ignition advance is fine with a little binding



carefully degreased ignition area. shaft after grease removed showed a tiny bit of rust. binding ignition advance. remove rust with 1200 grit crocus cloth, then relube with moly grease. (moly or silicon grease??)



ignition advance now moves freely without binding. will put a touch of moly grease before going back. nice touch by German engineers designing advance to only go on one way. locking nut will be put back with medium strength Loctite (blue). ignition advance is handled very carefully as not to damage tiny springs.



a layer of silicon will be applied on final installation

[disston]

I do like to renew the grease under the advance unit when ever I replace the points. I usually use something light like even motor oil. There is a specific grease. Bosch made it. There are a couple of specific greases in the points area. Another is for the rubbing block of the points, can be smeared on the cam of the advance unit. That one, the grease for the rubbing block/cam, is a generic points cam grease that even American companies made. Used to be really common when everybody ran points but now you have to hunt for it. The rubbing block will wear uberfast without it.

The points plate looks in good condition.

The springs on the advance unit are replaceable. They are available in two versions, regular and heavy duty. A parts guy may know which one is right for an R90S or he will just give you heavy duty like everybody else because, of course, heavy duty is always better, ain't it? The springs do get weak but not till higher mileage than I think I remember you have. they are the only part of the advance unit you can buy separate. Don't loose the tiny washers and/or e-clips if you take the unit apart. Eventually you may want to take the advance unit apart, we like to polish them to make for smoother operation.

The locating D slot arrangement is nifty. Since the ignition is a lost spark two cylinder affair they could also have used something bi-directional. The D slots usually have a little bit of slop to them but not always until later in life. When tightening down the small nut the unit should be held one way or the other and this direction used regularly. Sometimes on very high mileage units this practice becomes criticle (like on my R90/6, mileage unknown).

Be extra careful when tightening the small nut. Breaking the tiny threaded portion off is the most common damage done to an Airhead by the owner/mechanic. I think we have all done it. Using Blue Locktight is OK I guess, I like Blue Locktight.

Charlie

[_cy_]

thanks for all help everyone!!
especially solo lobo for sending out another diode board.

here's a few pic's of new board in place, naturally with battery disconnected.
the important question is... do I have all the wires hooked up correctly?

don't want to short new board out too..

[SOLO LOBO]

This thread is about to get very exciting! Can't wait to see your "S" running!

Here's a link to downloadable wiring diagrams (at the bottom)

http://webcache.googleusercontent.co...iagram&ct=clnk

[_cy_]

Originally Posted by SOLO LOBO

This thread is about to get very exciting! Can't wait to see your "S" running!

Here's a link to downloadable wiring diagrams (at the bottom)

http://webcache.googleusercontent.co...iagram&ct=clnk

thanks again for all your help!

yup almost running, going to splice new wire into points until new points gets in.

downloaded wiring diagram, but cannot figure out how what wires plug into where on diode board.
don't want to short out new board

[SOLO LOBO]

This might help, different bike, same system...

http://www.advrider.com/forums/showthread.php?t=493178