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GS Restoration

B

brianthack

Guest
A few months ago I picked up a 91 R100GS project bike. It had sat outside for at least 2 years in coastal California, and almost all of the cast aluminum has suffered varying degrees of oxidation, from light to pretty heavy. The frame has a lot of rust coming through, but no significant pitting. The spokes are wasted. Miraculously, the body work is in good shape. And it fired up before I started dismantling.

I have stripped the bike down- removed motor, separated the tranny from it, removed the entire rear end, yadda yadda. I'm trying to establish an order of things for restoration, and looking for some input.

I'm pretty sure I'm going to have the cast parts soda blasted. Past threads seem pretty supportive of this method. Do I need to strip the crankcase all the way down, gut the tranny, etc, before doing this, or can I just mask/plug any openings?

The other thing I could use some advice on is cooling fin repair. Two fins are broken on the right-side head, and I don't have the fragments. Anybody been through this? About how much did this repair cost, and what kind of shop did you take it to? Also, to get technical about it, does anyone know how much cooling power is lost by the absence of a few fin fragments, and is this likely to damage/warp the head or valves?

Sorry for the glut of questions in one thread. I will post pictures shortly.
 
Welcome to my world :)

I am working on a 91 R100 GS as well.

Total strip to the frame.
- powder coated frame and crash bar
- engine (45,000 km) never bothered to start it! did not want to potentially cause any issues... stored for years!
- new valve guides (major wear on one side only, but doing both)
- Timing chain (while I am in teh engine....)
- rear seal (leaking)
- new rings (evident engine was running lean)
- exhaust pipes
- front caliper refresh
- electrical clean up, relay replacement.. bad corrosion
- tail light
- new battery
- seat cover on orginal seat, corbin found in Black and Yellow
- Olhlin rear shock
- Carb clean up and refresh with all new jets and needles
- Tranny seems fine.. will leave it alone.
- new used gas tank.. major rust through in bottom, thanks to a BMWMOA member ofr that, I was worried on this item.
- forks to be refreshed
- seal in rear hub, drive shaft seal
- stearing head bearings
- front wheel bearings
- aggresive DS tires

- I will be cleaning all the oxided alum with wd40 and steel wool... then alum polish and fine steel wool... better suggustions always welcome... assembled rims / hubs are going to be a lot of fun ;)

Here is what it looked it when I picked it up.....
 

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here is what it looks like now slowly going back together....

notice the Solid oak work stand... does not go up and down... I have two different stools with different levels ;) makes the hours of tracing electical issues more comfortable....

who would have ever guessed that nothing in the electrical system works unless the power shedding relay gets its' ground through the positive feed to the starter solinoid... that took me sometime to figure out.. German Engineering at it's best I guess....
 

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Wow, my checklist is nearly identical. While I'm at it, I'm going to have Bruno make my driveshaft greaseable, going to probably open the gearbox myself and have the circlip done (both preventative), and I have to replace the fork tubes (I already have a nice used front end).

So far so good on your project, keep us updated with photos and I will do the same.

For some reason I can't track down a good "before," so here's a "during" with the motor already gone and the swing arm removed. As of right now, it's a heap of parts in ziploc bags, cardboard boxes, and on shelves in my woodworking shop.
 

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The great thing about getting this deep into a bike is on remote trips you know exactly where everything is and how it works in case something happens.

If you are thinking about painting your frame there was a recent thread on Powder Coat vs Wet Coat, you might want to cruise through to pick a method if you are going for a paint job.

Good luck I will post some more picks this weekend as I do the Stearing Head Bearings and Brake Caliper refresh.

R's G
 
I finished a complete '92 R100GS PD restoration/upgrade a year ago...sat on the CA coast for 5-6 years.

He took it to the Arctic Circle last summer.

Powder coating, rebuilt suspension, new wire harness, heated grips, dual driving lights, new paint, R&R tranny, heads, etc.
 

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Nice Work!

Guru, your bike looks great, I look to the day when I'm looking back at a successful project myself.

Did you have to deal with a lot of aluminum oxidation? That's one major thing I'm trying to wrap my head around right now. Nothing indicates the need to dig into the bottom end, so I'd rather not do so, and therefore am looking for a non-invasive method. Also staring with some dismay at the prospect of many long hours with scotchbrite and WD-40, although if that's really the way to go, I'll just suck it up

Once again, nice work!
 
the prospect of many long hours with scotchbrite and WD-40, although if that's really the way to go, I'll just suck it up
Once again, nice work!

this is the realization that I have come to in talking to a local BMW restoration expert....

My first step in my cleaning was the little red parts cleaner you see in the background of the pic above... $29 at TSC :), then $89 of solvent. I removed the rivot that holds the lid arm so that I can swing it fully open, then with two 1x2 boards across the width of the cleaner I was able to sit either the tranny or block on top... with a varsol brush/hose connected to the pump output and some coarse steel wool it has cleaned up pretty good so far with very little effort. Once the cylinders are are back on minor strubbing of the block with wd40/steel wool will sure make it pretty.

I have yet to work on the rims and hubs... that's going to be real fun. I have no reason to tear the wheels down as the spokes are in good shape and they are running true... so getting around all the spokes on both the rim and hub is going to be lots of time ;(

Anyone have any tricks to better cleaning methods???
 
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Hi, I'm doing same on 86 r80rt, I have had good luck with air die grinder with a cup wire brush and wd40

Good luck
 
Couple ways to deal with salt air cruddy stuff (technical term). For the aluminum cases, swing axles etc., see if someone locally has a soda blaster. Uses baking soda so no grit to get into bearings or seals. That will get the hard stuff off and leave a decent finish.

To get back to the original shiny but porous look, now you get out the Scotchbrite and WD40...and a heat gun.

Scrub, scrub scrub, then hit it with the heat gun..scrub a bit more and spray more WD40 to wash off the mess, wipe clean..when the finish is where you want it, hit it with the heat gun again and spray WD40...and let it sit.

Heat gets the pores open, WD40 gets in the pours and cracks...and dries leaving a coating.

When the engine, tranny gets dirty, just spray WD40 and the result is an easy wipe off back to a shiny.

Started this on my '68 R60/2 10 years ago and a wipe down with WD40 brings it right back to original.
 
Well yesterday was Steering Bearings, Front Brake and more electrical cleanup.

Steering head bearing were straight forward with adjustment per this link, but wow without the bars on for leverage they feel tight... with the bars on .... smooth.

www.largiader.com/bearings/

Front Brake...

Problem: applying brake it would lock the wheel, only way to move the bike would be to pry pads slightly apart.

Fix: new seals in the caliper and clean up of the reservoir and piston.

Caliper Seals - dismantled the caliper halves, with them separated I used compressed air through small feed through hole, while plugging inlet with finger, to pop the caliper pistons out... wow they were in there tight! General cleanup and then reassembly with new seal kit.

R100GS022.jpg


R100GS023.jpg


R100GS024.jpg


Piston and cylinder - dismantled assembly and cleaned throughly. There was a lot of crap in there! So much that the feed hole to the piston from the reservoir was plugged solid. Cleaned and flushed with fresh Brake fluid. I was worried that I was going to need a new piston at $78 but it's ok :)

R100GS021.jpg


R100GS020.jpg


Reassembled system with outcaliper, flushed hoses and steel line. Works great now!

R100GS026.jpg


On to the rear end now.... and then to the wheel cleanup.
 
Where did you source your caliper rebuild parts? Dealership? I have to do the same...
 
Steel wool and aluminum do not mix

Hi Graham;

Just a word of advice on cleaning the aluminum---do use Scotchbrite instead of regular steel brushes or steel wool---otherwise tiny bits of steel break off and get imbedded in the aluminum pores and you'll end up with galvanic corrosion later on...:nono

A stainless brush would be OK but Scotchbrite and WD-40 will work well for this task. Hope this advice is not too late.

Looking forward to seeing further progress on your bikes, guys---best of luck to you both.
 
a little late... but not so much.... I have mostly used scotchbrite until I wore it down.... I will go back over the few items that I cleaned with the steel wool with the scotchbrite to pull any fragments out.

BTW... the bike will look good and the mechnics will be very sound, but I have no intent of restoring to showroom condition, the GS will be ridden :) my objective is to simply restore it to a reliable adventure bike that I can explore the world on.

So as you see the progress judge it in that regard.....

G
 
The following is a bit more of what I have had to deal with the "bargin" R100GS that I am working on...

1) Right exhaust nut would not spin at all even with heat... so it was split to find this... The thread has been rebuilt and I am awaiting it's return.

2009-11-07015.jpg


2) upon pulling the Tranny I found that the main seal was suspect.. so it was replaced... report on the work back was that the oil pump cover was loose and leaking as well so new seal on it. I also had the timing chain replaced and the rest of the block checked out.

2009-11-22090.jpg


3) after 8 years of sitting with fuel in the Carbs...

2009-11-22025.jpg

2009-11-07013.jpg


4) Cleaned up with Kleen-flo carb cleaner.... wow powerful stuff!

2009-11-22026.jpg


5) Upon removal of head found guides in a state of needing replacement... new guides and valves being reseated on both heads.

2009-11-22036.jpg


The heads and block work should be complete next week, so I can finally get the engine back in next week and attempt a start for the first time ever :)
 
Those carbs look incredible!

My project has slowed lately due to workload (not a complaint btw), but this week I did manage to get my driveshaft off to Bruno for greaseable u-joint upgrade. Going to order brake rebuild parts and engine gasket kit from Capital Cycle this weekend, so maybe I can get back into the swing of things late next week.
 
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