First Airhead: 1975 BMW R90/6 project. Help needed.

[US_Marshall]

I like "Simple Green" to clean of the oil residue. For the heavy stuff you might want to get a plastic scraper so you don't damage the aluminum.

[tenderfoot]

My bike also came without the centre nut for the tappet covers, luckily the thread was OK and I simply took a length of threaded bar (8mm ?) screwed it in untill it bottomed against the head and sawed it off at the correct length. The nuts are quite expensive and the torque is so low I suspect they are largely cosmetic, the two back nuts do the job quite well on their own. Someone will definitely chime in calling for my head on a platter for this heresy .

[rebelpacket]

I use kerosene and a paintbrush to clean off the porous metal surfaces. Then some simple green or equivlent to remove the rest of the kerosene. I like the buffing option though, those alloys look beautiful.

[BeachZack]

Originally Posted by tenderfoot

My bike also came without the centre nut for the tappet covers, luckily the thread was OK and I simply took a length of threaded bar (8mm ?) screwed it in untill it bottomed against the head and sawed it off at the correct length. The nuts are quite expensive and the torque is so low I suspect they are largely cosmetic, the two back nuts do the job quite well on their own. Someone will definitely chime in calling for my head on a platter for this heresy .

Yeah I'm sure its not big deal and if they really are stripped I'll put in a helicoil

Originally Posted by rebelpacket

I use kerosene and a paintbrush to clean off the porous metal surfaces. Then some simple green or equivlent to remove the rest of the kerosene. I like the buffing option though, those alloys look beautiful.

I've heard that simple green is corrosive to aluminum, any problems with doing this?

[tete]

Originally Posted by BeachZack

I've heard that simple green is corrosive to aluminum, any problems with doing this?

If this is true then my entire bike should be falling apart soon.

One thing I have always had succes with is simple green. It's not really the fastest way but has consistently been the safest least abrassive approach.

I can say with a certain amount of confidence that I have no / zero data supporting my claim except for my own experience using it on 3 bikes now.

[pthomas]

Simple green has a corrosive agent in, get the aviation version that doesn't have that agent.

[disston]

Originally Posted by tenderfoot

My bike also came without the centre nut for the tappet covers, luckily the thread was OK and I simply took a length of threaded bar (8mm ?) screwed it in untill it bottomed against the head and sawed it off at the correct length. The nuts are quite expensive and the torque is so low I suspect they are largely cosmetic, the two back nuts do the job quite well on their own. Someone will definitely chime in calling for my head on a platter for this heresy .

Nah. We'll have to find another reason to off with your head. The valve covers will stay on and not leak if held by either the center nut only or the two back nuts only. I guess it's what you might call redundant. No idea why this may have seemed logical. Maybe it is.

I've been lucky with the two sets of heads I've used over the years. One set still has the original threads and the other has nuts behind the threads to fix them. Either system works as a repair.

To make the added nuts behind the threads repair a proper sized nut is thinned with a grinder so it is thin enough to fit in the small space the stud would reach if it is long enough. Red Locktight it in place with the stud. It never has to come out. You usually need a longer stud for this repair.

[wirewrkr]

Originally Posted by tenderfoot

My bike also came without the centre nut for the tappet covers, luckily the thread was OK and I simply took a length of threaded bar (8mm ?) screwed it in untill it bottomed against the head and sawed it off at the correct length. The nuts are quite expensive and the torque is so low I suspect they are largely cosmetic, the two back nuts do the job quite well on their own. Someone will definitely chime in calling for my head on a platter for this heresy .

Not true.

[tenderfoot]

Originally Posted by wirewrkr

Not true.

Accepted, but as Diston said they are to some extent redundant as I also did not experience any leakage while they were gone.
The engine does look better with them fitted though.

[disston]

Originally Posted by tenderfoot

Accepted, but as Diston said they are to some extent redundant as I also did not experience any leakage while they were gone.
The engine does look better with them fitted though.

I have run my bike with only the two small nuts in the back or the larger center cap nut in front and didn't get any leaks. But I didn't leave it this way for very long. Wirewrkr says they are not cosmetic. So I'll keep using them.

[Bluebone]

Originally Posted by Brun

Clean your alloys with a solvent and a kitchen scratchie (Scotchbrite or similar). The castings have pores that fill with black grime. Best treatment I've found is Rub'n'Buff. A little 15ml tube will do all the alloys from a couple of bikes.



Just rub in a small amount with your finger and buff off with a rag. It leaves a waxy film that apparently lasts a long time.
RnB comes in different colours. The one used above is Pewter. Lots of folks use Silver Leaf for a brighter appearance.

this stuff works pretty well but you might wanna just rub on some type of solvent like lacquer thinner or xylene 1st to get the easy stuff off so the Rub'n'Buff will be more effective on the hard parts.

[rufusswan]

Originally Posted by disston

I have run my bike with only the two small nuts in the back or the larger center cap nut in front and didn't get any leaks. But I didn't leave it this way for very long. Wirewrkr says they are not cosmetic. So I'll keep using them.

That center nut is quite handy, in that allows you to install the valve cover and it's two dollops of oil quickly and center torque the cover into place. Once sealed up you can then can sip your cold beer and do the somewhat finicky install of them two tiny washers and nuts.

[dmftoy1]

Pb blaster and scotch brute pads works pretty good too, but it's gonna take ALOT of elbow grease on mine I think.

[BeachZack]

Ok, quick rundown on what is planned for the bike.

Swap to a modern USD front end. I've seen successful swaps using GSXR front ends done before, does anybody have any information regarding a swap like this?

Rear monoshock conversion. Planning on running a rear monoshock on the bike similar to Sparkymoto's build and Leadnuts build. Big thanks to both of them for documenting all the fabrication so well.

While I was putting the swingarm back on the frame in order to take it to my fabricator, I realized while doing so that the swingarm may not be properly aligned, which would be important in lining up the mounts for the rear shock.

Any tips on how to align the swingarm/rear wheel? Should I focus on the front end swap first in order to be able to align the front and rear wheels before the swingarm modification?

[Paul_Rochdale]

Have you heard the term RTFM?