Working on and off in spurts the past week or so.
Started working on the tank interior. First stage was a good rinse with Dawn dish detergent and hot water which removed a bunch of loose stuff. This was followed by a four day soak with two gallons of white vinegar and a scrub with a red Scotchbrite pad before dumping the vinegar. This was followed by an overnite soak and Scotchbrite scrub with Goo Gone to get more of the melted vibration damper out. What remained came out pretty well with paper towels and Isopropyl Rubbing Alcohol. Looks pretty good to me now.
Unfortunately, the damper goo seemed to have a real affinity for the fuel level sender, and in the course of cleaning it I destroyed the element and the wipers. Fortunately, the wiring for the fuel pump is still good, so I can run the bike using the tripmeter to judge when I need fuel until I can find a reasonably priced replacement.
The battery arrived and I wasted no time connecting it to troubleshoot the undefined electrical problems the previous owner said it had. Turn signals and horns didn't work. Cleaning the contacts on the bulb monitor and the combination switch connectors cured that problem. The horns still didn't work, and I found a dead horn relay. Replacing it didn't help, so I pulled the horns and found there was no continuity between the terminals on one of them. Turning the adjusting screw with 12V applied got the first horn working. The second one came to life with a gentle tap. About 15 seconds of continuous operation with a rag stuck in the throats indicates that they are in good working order again.
While I was at it, I pulled the fan relay and jumpered the terminals for the relay contacts on the socket. The fan works, which didn't really surprise me since the P.O. mentioned that it had been replaced at some point. To my great pleasure the electrical system all works now.
Since the bike was so dirty, I thought it would be a good idea to clean the ignition switch while I had things apart. Turned out to be a good idea as there was a bunch of waxy looking crap all over the place around the contacts.
Next was to bleed the brakes to clear out the brown D.O.T. 4 that was in the system. Pretty straightforward, and now the brakes have clean fluid and actually feel better than on any of my other bikes, even the rear master cylinder has a firm feel!!!
With all those jobs done, I was waiting for parts from MaxBMW so I could continue. I was shocked to learn that BMW has the lowest price I could find anywhere for submersible fuel line. I took the opportunity to remove some more of the body parts, specifically the rear tail cowl. I was expecting to find the rear loop to be rusty like every other brick I've owned, but surprisingly, it was in perfect condition without a single spot of rust or paint damage. I'm learning that this bike is in much better shape than I thought.
While waiting for parts I decided to check valve clearances, compression, and change the oil and filter. When I drained the oil I found it was brand new and clean, along with a clean oil filter. Must have been serviced at the dealer before it's long hibernation.
Valves were all in spec, but two of the exhaust and one intake were at the tight end of the spec so I changed the shims to get them to match the others. All valve clearances are now at the top of the spec.
Compression was good on cylinders 3 and 4, but really low on the other two. A shot of oil in those and they are all withing 10 psi of each other and reading nice and high.
Installed new NGK D7EA plugs and cleaned the plug wires and sockets followed by a bit of dielectric grease to make them easier to remove. The plugs I removed were brand new Bosch, made in Germany, not India, so I guess they were installed by the dealer those many years ago. I put them in my spares stash.
The crank breather Z-tube looked good except for some minor external cracking. I had a spare, so I replaced it.
I installed the injectors, and with their ports in the head filled I was able to do a good wash of the bike. Cleaning the bike with S-100 removed a LOT of dirt, leaves, and who knows what. What remained was in stunningly good shape. This bike doesn't need hardly any cosmetic work on the frame beyond a bit of compound on the chalky paint, and even that isn't really critical. The engine is in pretty good cosmetic shape as well. I am seriously reconsidering the frame up rebuild.
I did find some chafed wires in the taillight wiring harness, but I had a spare and replaced it. The wiring is now in perfect shape, as far as I can see. Even the connectors look clean, but I'm still shooting them all with Deoxit and coating them with a film of dielectric grease and putting Vaseline on the connector shells to make them easier to separate
The parts for the tank and fuel lines arrived on Thursday. An hour or so of putting things together in the tank and it was ready to see if the engine was going to start. Four or five quick stabs at the starter to prime the system and holding my breath I hit the starter and after a second or so of cranking the engine coughed and settled into a rough idle, spewing large clouds of oil smoke from the oil I injected when I did the compression test.
After a couple 15 minute sessions of idling the smoke cleared enough to do a throttle body balance. I found and replaced two of the vacuum caps that had bad cracks in them. The engine now idles fairly smoothly, but two of the adjusting screws are erratic, so I shot some carb cleaner in their holes in the throttle bodies. It helped, but they could still be better. Will be addressing this again when I get a new can of carb cleaner.
With the fairing removed I did a good cleaning with S-100 and replaced the broken headlight with a spare I had. Outside of a few stone chips and some crazing around a mirror mount the paint is in pretty good shape. Wow! The more I work on this bike the more it looks like it doesn't need much work.
With the engine running it was time to check the ABS system. Here's where I have found a bit of a mysterious problem. The ABS light doesn't go out when it should, even though there are no faults when I check for them. I've done several attempts to clear/reset the system, but the flashing continues and no faults are indicated. Puzzling...
Stay tuned. Photos are still in the camera, I'll be posting them tomorrow.