Since this bike sat for more than 25 years and I found water in the oil pan, I replaced the connecting rod bearings and the oil pan and oil pump suction gaskets. The bearings were in good condition, so that was a relief. The oil pump suction gasket was brittle so it was time to replace it. None of the oil pan bolt threads were stripped, so that was a good thing. I also had the oil pan, that was painted orange by a previous owner, vapor blasted by the Colorado Vapor Blasting division of Vintage Twins, a local independent shop in my hometown of Arvada, CO. When I told them I was going to auction this bike and donate all the proceeds to the Motorcycle Relief Project, they generously provided me a nice discount on the work. 🙂
Here is a before and after picture of the oil pan.
The Original Orange Oil Pan
All Done With Vapor Blasted Oil Pan
All Done With Vapor Blasted Oil Pan
You can read about how I do this work and see a short summary video here.
This “project” bike has over 63,000 miles on it. It’s not uncommon for the timing chain and crankshaft sprocket to wear enough at that mileage to affect valve timing. Too much slack causes uneven timing of the valves. If valve timing varies, then ignition timing will not be optimal. In situations with a lot of wear, the chain can be heard slapping inside the motor. As I’ve never heard this bike run, I do not know if the timing chain is that loose, but that much slop in the timing chain is more common at 100,000+ miles on the chain.
I repainted the inner timing cover and you can read about that work here:
This “project” bike has been sitting for over 25 years. So, for reliability, I’m going to replace the charging system which consists of the alternator, diode board and all associated wiring. I may try to rebuild the electronic ignition sensor, aka, the “bean can” that uses a Hall effect sensor to trigger the ignition. This document covers how I remove the components.
Also, I plan to replace the timing chain, crankshaft timing sprocket and the nose bearing which are behind the inner timing cover that the charging system and electronic ignition sensor are mounted to, so I have to remove all these components before I can remove the inner timing cover.
The original alternator looks a bit bedraggled.
Original Alternator Looks Bedraggled
I’ve replaced charging systems on other projects. Here are links to those documents.
There is a new podcast produced by, Daren Dortin, called “Airhead Type 247” available on Apple Podcasts and Spotify. “Type 247” is how BMW identifies the airhead motor and associated motorcycles from 1970 through 1995.
Daren is interviewing folks who have a lot experience with BMW airhead motorcycles. So far he has talked with Ted Porter, The Beemer Shop, Rick Jones, Motorrad Elektric, and Bud Provin, The Nickwackett Garage.
Daren posts a new podcast once every two weeks, +/-. He owns a number of airhead bikes and has had a career in radio for more than 30 years. His interviews open the door to learning more about folks who actively support the airhead community. You might want to subscribe to his podcasts and relax with a cup of coffee, or an adult beverage, and listen to the opinions, stories and experiences of longtime airhead folks who are passionate about keeping these Bavarian creations on the road.
Well, all the work on the rear of the engine is finished as I have completed installing a new clutch provided for free from Euro MotoElectrics who offered to provide free parts for this charity rebuild project to benefit the Motorcycle Relief Project.
Here is the link to the document about how I did this work.