One of the last things I had to do was weld together a tail light/license plate bracket. I had to wait for the light to show up so I could figure out the relationships. Here's what I managed. (Note the last time it was registered - 2002!)

I got the bike on Nov 1, 2015 and it's pretty much done as of this week - Aug 7, 2016. I guess that's about 10 months. Since there were long stretches where I didn't do much, I guess that's not bad. The bike turned out OK. If was planning on making this my bike I would have gone further, but I was primarily interested in spending as little as possible to get it back on the road with cafe styling. My inspiration was something like these, but they have $1,000's in custom paint and body work. Maybe next time.

Mine turned out a lot more stock looking. It runs well, and seems to drive well. I need to get it registered and do some little tweaks and adjusting.

I probably should have written this in a more realtime fashion so I can remember all the bits. Once the painting ordeal was complete, the reassembly went reasonably quickly. I had been collecting bits over the months, so I had a lot of the parts I needed once I dug in. First up was respoking the wheels. I used Buchannans SS spokes and nipples. I also stripped and polished the rims. Things turned out pretty nice.

Next up was to get the engine back in the frame - without scratching things too much! I was working by myself, so I ended up putting the engine on it's side and then lowering the frame around it. I then replaced the lower mounting bolts, turned it upright and it worked great. It was simple matter to then bolt on the transmission.

I then mounted the swing arm and set up the wheel bearings. BMW's use a tapered roller bearing stack that needs the preload set up. I'd never done this before, so it was a bit fiddly, but in the end things seemed to go together correctly. I then mounted the tires and balanced the wheels.

I had decided to make a custom battery holder from the start. I used a blanking plate supplied by Boxerworks to eliminate the stock air cleaner and in it's place, on top of the tranny, I mounted the battery. I thought it came out pretty well. I also decided to put the crank case breather inside the starter cover. I hope it doesn't spew oil in there. I wanted to use peashooter mufflers, but couldn't find any in my budget. I ended up going with Dunstall replicas. Although they didn't look exactly like what I was after, they ended up sounding great.

I went through a bit of hell with the front brakes. The original set up had the master under the tank and was actuated by a cable from the front handlebars. Since the original master was toast (rusted and pitted) and the throttle control was trashed (corroded, teeth worn, etc) I needed to replace them. I also had read this set up suffered from a lot of issues (leaking fluid under the tank, poor braking due to the cable, etc. ) that I changed to a later style. This used a handlebar mounted master and simple junction block under the tank. I also upgraded to SS lower lines. It took a bit of fiddling, but came out OK.

I then started in on the wiring. I was able to use the original harness without much modification. All that was really changed was the ignition as it had a Dyna III and aftermarket coil. (I also had to fool around with the turn signals, taillight and horn.)

I was getting close to completion. Here's a shot just before turn signals, taillight, horns, grips, etc. I had originally considered painting the body work, but frankly ran out of interest and budget. Also the original paint cleaned up well enough I decided to use it. Unfortunately, the battery color didn't work. Oh well. 

I have to wait for a few bits, so I can't start it up and try to ride it. I'm hoping the transmission (which I didn't do anything to) is OK!

Where we left this project months ago was I had managed to get the engine back together after discovering shot rod bearings. Next was to put it back in the frame and get this project to a roller. I really want some of my shop space back!  That necessitated painting the frame and other bits.  

Let me preface this - I hate painting. It's not my thing. In the end I'm kinda aiming for a decent "5 foot" finish. (You know, looks good from 5 feet away or more?)

I've always wanted to try automotive paints and thought I would give a try on the BMW. I decided to use Eastwood paints - they target the DIY market and their stuff is a good compromise between cost, east of use, quality and variety. I chose the DTM Epoxy Primer and a Single Stage Black Urethane. But first I had to build a spray booth, sand down or media blast the parts, figure out a way to mount the frame so I could get at it, and acquire some safety gear (fresh air respirator, hood, suit, etc). 

There's tons of info on the net about building you're own small booth. I went with the painters plastic over a PVC frame, cheap box fans with furnace filters, and fluorescent lights style. 

What this is really for is two fold - 1) to contain the overspray and fumes, 2) keep contaminates out of your new paint finish while it cures. This style of booth is probably just OK at both, but better than nothing. I did notice there definitely was a positive pressure as there was overspray blown out all around at the bottom of the frame and floor joint creating yet another thing to try to clean up.

Here are some various bits masked off. I think this was the most enjoyable part of the whole thing. It's clean, easy and kinda looks cool when you're done. 

Ready for paint. Turns out kinda. Well lets just say I learned a lot. The overarching problem was the fact I had too much going on in here. The parts were too close together, they were too high to paint comfortably, I had a lot of trouble getting all the sides (I had to hold and manipulate with one hand while painting with the other. I got lots of runs. I got lots of overspray. I missed some places.

​It was horrible. 

Primer on. Another mistake, don't get black primer if you're going to shoot black as a color coat. You can't see where you need to paint. I should have used a grey primer. 

I ended up sanding the primer out on the frame sections (where there were runs and stuff) and respraying. (The other pieces ended up being good enough). This would have gone great had my stupid painting hood (which inflated due to the fresh air system and pressurizing and popping up the top a good 6 inches) not collided with my fresh 2nd coat. I'll have to sand that down and touch it up tomorrow. Sheesh!

Today I started in on the wheels. They're pretty ugly. 

I need to determine hub offset. The front was easy as the hub is symmetrical and it's centered on the rim so I didn't need to measure. The rear is also apparently centered, but the hub is asymmetrical, so I decided to measure where it sits. I just laid a straight edge across the hub flange and measured the distance to the rim. Looks like about 3.5/64 or 1.4mm. 

The nipples were pretty badly corroded, so I just used the Sawzall to liberate the hubs.

If you recall, when I drained the oil out of the final drive I found a bits on the magnetic drain and a chunk of metal that was a wee bit concerning:

After reading up on airhead final drives, I realized I could remove the inner cover without disturbing the gear setup. (That anti-seize lube crap is a bitch to clean out of the splines!)

Well I found the rest of it and I was able to put Humpty Dumpty back together again - sorta. I couldn't find a parts diagram for the final drive, so I have no idea what this is, but it looks like it's supposed be a trust washer that is located at the end of the needle bearing in the center of the drive.  

You can see here there is metal smeared on the shoulder of the flange and there is some blueing from overheating visible too. 

So this drive is toast. Too bad as the bevel gears actually look very good. This was a 32/11 drive with a ratio of 2.91. It's one of the tallest rears BMW made (I guess the R100S was supposed to be a powerful long range highway cruiser.) I've decided to replace it with a used 32/10 (3.20 ratio) unit off a '73 I found on eBay. This will screw up the speedo drive ratio, but who cares? Bonus is the brake pads are included - I hope they're good enough to use. 

Not so great news in the form of lots of metal fragments stuck to the magnet when I drained the transmission oil. I didn't take a picture, but it was more crap than I'd like to see. Nothing big or or chunky, mostly dust like with thin flakes. Probably the gear faces. 

The final drive was worse. Way worse. Big chunks of metal came out, including something rather significant. This really should be rebuilt, but not by me. 

It appears Uncle Ben was not too up on maintenance. The engine, trans,final drive and tires all showed signs of lack of attention. I expect this bike was just never serviced and ridden hard.

In keeping with my strategy of getting the engine squared away before any other work, I finished the engine and rigged up a test stand. ​

So it seems to run well enough, no weird noises, leaks or other red flags. That gives me the go ahead to start working on the rest of the bike.

Mostly been cleaning things up. Built an attachment for my HF Engine stand. Started putting a few things back together.
Cleaned up and valves back in:

 My first priority is to determine if it's worth spending much money and time on. I wanted to have some fun with it, but not get sucked into to a long drawn out project. I also wanted to spend as little as possible. I figured I'd better determine if the motor was any good. If that needed a lot of attention, I'd stop right there. I wanted to get it running, so I'll need to rebuild the carbs, change fluids, filters, and figure out if the pistons,valves, rings are OK. Fortunately with Airheads the cylinders are very accessible, and the carbs had to come off anyway and the headers where rusted through, so in about 5 minutes... (I just sawed through the header pipes as they were frozen into the heads). 

​Left side head and piston:

Right Side:

I don't have a picture, but it looks like the bores are OK. The right is showing a bit more wear with a few lengthwise scratches, but nothing horrible. You can see the hone crosshatch pattern, albeit faintly in some areas, but it's there. I popped the valves out and found a bit of trouble there. The exhaust seats have seen better days (I think one had been sitting in the open position and got a bit of condensation/rust damage. The exhaust valves also have some pitting (maybe from oxidation or combustion??). My plan is to use lapping compound to see if I can clean up the seat faces enough. If not, then I have decide if its worth spending the money. 
Heres a pic before and after glass beading and jugs:

There was a bit of damage to the exhaust port threads on the left head. I think it'll work, but they are only about 50-60% there.
So I'm willing to put this back together as is with the knowledge that the valves may not be so hot. If I really like the bike, I can always pull the heads and get em done right. That shouldn't be too hard.

My plan had been to tear things down enough to make sure the engine was OK, clean things up, and as a result of tearing down - replace most of the seals. My initial thinking was to get the cylinders off and check the rings and bore, thinking they would probably be the worst of it. Once I got them off however, I found the conn rods had a lot of slop and weren't spinning very freely (kinda notchy). So that meant pulling the rods, which meant ordering the conn rod bolt tool. Skip forward a week or so and the tool showed up. Pulled the caps and found:

Yuck!
I found the rest of the big end bearings in the oil filter pleats! This bike probably had quite a knock, maybe that's why it was off the road??? However, the crank looked perfect - I guess BMW journal hardening is very good (better than my old Norton!). New bearings and I think we're good. 
The worst of the issues I've found so far have been these bearings being trashed and the valves (both guides and seats) looked a bit worn. I'm going to simply lap the valves and put in the new bearings then on to reassembly!