I know what you did last Winter

On this episode of I know what you did last Winter- major projects included BMW R75/6 rebuild and MG Stelvio Sump Pump Gasket replacement.
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So it started with freshening up the heads since the BMW's in the 70's were raised to ingest leaded gas but a steady diet of ethanol laden Corn Gas had wreaked havoc on the valve seats. This led the mind to wander (trigger warning- the following includes going down a rabbit hole with money and effort never to be recouped in this lifetime). Can't just have fresh heads and leave the rings alone....not after 50k miles. I bought this bike when I was 20 so the majority of miles are mine.
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Off with the cylinders. Now 1976 had iron liners set in aluminum cylinders.
-Options included a re-hone with hard to find and expensive oversize pistons and rings
-Send off for Nikasil plating and size to stock pistons and new rings. Nikasil plated iron is ok at best.
- Source used 800cc cylinders which had Nikasil coating when new with piston and rings. 800cc Cylinders have a ridge that would need to be machined off.
- Purchase and install 1000cc kit, Nikasil Cylinders, Pistons, Rings and be done with it.
I went with the latter
But wait...there's more...if you decide to go down this road...you might as well check the lower end, the bolts are stretch type so have a set of those ready, oh and might as well put new bearing shells in since...well, since you're in there:

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The left side was good but the right side looked like it passed something through the bearing sometime in the past 46 years. Nothing catastrophic but enough to catch a finger nail.
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Pulled the lifters and checked for pitting- this is what suffers with use of modern low zinc motor oil. Once the coating on the lifter becomes pitted, the cam takes a beating and its all down hill. Mine looked good so back in they went.
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Bench O' Heads!
I'll take Cylinder Heads for $1000 Alex: The question is "Where are upgraded BMW Cylinders Made?"
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What is ITALY...by Gilardoni....So both my R75/6 and Eldorado have a set of Gilardoni kits...lots of shared DNA in my garage- 2004 Harley Road Glide and 1974 Eldorado have identical floor board pads which is something you notice while staring creepily in the dead of Winter, at night, hiding from the women in your life...anyways.
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Cylinders on, Pistons in place, Rings in correct order and orientation...but wait...the final drive ratio on an R75/6 is 37/11 which will make a 1000 cc motor hit red line way to early...I placed an add on the Airhead forums seeking a final drive with 33/11. Some German guy had one on fleabay way over priced. I made him an offer- he never responded and then he stated..."eit haz been zold" Then out of the blue I get a call from a Michigan area code. Guy said he had one in the basement. Fill thread was stripped (one of the most stripped plugs on an Airhead) but other than that in good condition. We agreed on a fair price, sent him a check and the last piece of the puzzle fell in place.
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Early in the project, I decided to remove the Windjammer fairing but doing so exposed a slight dent in the tank that was placed there by a service tech who had so much crap in his his work area its safe to assume something fell on my bike. He denied it. Anyways- since then, I never had a bike serviced from an outside source...All Baking Done On Premises from now on. I went ahead and had the tank sealed and painted.
With everything back together - it was time for initial start up. Want to seat these rings so with all riding gear on, started bike and rode off. No warm up period. Varied the speed with plenty of engine braking to pump oil through the cylinders. After the first 20 miles whatever break in occurred, did, so now just a matter of varying the speed for the next 600 miles and keeping it away from red line. Power increase definitely noticeable with the bike producing a considerable bark. Have to take it easy since the frame doesn't have the bracing that the R100's incorporated when BMW bumped up to this size. I didn't notice the chassis being overwhelmed by the power band though. Next on the agenda is to sync the carbs- I had to up the main jet since it gobbles more fuel now. Good Times!
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Nice work Mike. With 4 girls in the house it’s no wonder you get a lot of work done!

Where did you go for the tank repair and repaint?

Cam

Hey Cam-

I had the tank sealed and painted here: [You must be registered and logged in to see this link.]

Guy's name is Craig- he did a great job and saved me the trouble of trying to seal my own tank.

I sealed the Eldorado tank myself since I wanted to keep the original paint. Had decent results but once is enough for me. Eldo had a failed sealer from the previous owner so that was a chore trying to remove. Box of sheet metal screws, aircraft stripper, and endless shaking.