I remove the crankshaft to check the condition of the main bearings. In order to remove it, I have to remove the camshaft first. I use the tools I bought from Cycle Works to remove the crankshaft.
Cycle Works Stage III Tools
I asked Matt Parkhouse, a long time airhead mechanic who lives about two hours from me, to assess the condition of the crankshaft main journals and the main bearings. He found the front bearing was serviceable but the rear main bearing was just outside the maximum clearance. He replaced the bearing and now the front and rear main bearing clearances are close.
Measuring ID of Original Rear Main Bearing
Since I have to heat the front of the engine block to 275 F, I removed the stater motor and crankcase vent housing hose so they would not be damaged.
Here is the block with the crankshaft and camshaft removed.
I made a short video summarizing the procedure that you will find here.
I will replace the crankshaft sprocket, nose bearing, chain tensioner, rubbing block and the internal components of the oil high pressure relief valve. I will post a separate write-up showing how I do that.
I am going to replace the timing chain, crankshaft sprocket, crankshaft nose bearing, and the front main seal. I’m also going to pull the crankshaft to inspect the main bearings.
But first, I have to remove the electrical components and wiring inside the front engine cover that includes the diode board, alternator and ignition sensor, aka, the “bean can”, aka, the “electronic points”. I plan to upgrade the alternator and diode board to a 400 watt system. I also plan on opening the bean can to lube the advance mechanism and replace the Hall effect sensors.
Here is the before and after pictures.
Diode Board, Alternator, Ignition Sensor Are Inside Front Engine Cover
And, I shot a video of this work which is a bit long at 20 mins.
VIDEO: 1983 BMW R100RS Remove Diode Board, Alternator and Ignition Sensor
My goal in the video is to explain more about what the wiring under the front engine cover does and how it’s routed, as well as show how to remove all the components, so that added to the length. I’ll try to keep future videos shorter.
The inside of the bell housing as well as the shelf under the transmission showed oil leaks, so one, or all, of these are the likely culprits.
Grunge Inside the Bell Housing Suggests O-rings and/or Rear Main Seal Leaks
Oil & Grudge On The Shelf Under The Transmission
When I opened up the oil pump to take measurements and do a visual inspection, I decided that I had to replace the oil pump due to a lot of wear and tear to the rotors inside the pump. You can see how I removed and measured the oil pump here:
When I first got the bike, in debugging a low oil pressure light that came on, I discovered that the oil filter high pressure bypass valve was hanging by a thread. So, unfiltered oil was circulating, but I didn’t know for how long. Based on the condition of the oil pump and the scores I found in the rod bearings, I think unfiltered oil circulated for while. Not what I wanted, but I’m glad I took a look at the pump.
And, you can see a short video that summarizes the work here:
Due to what I found with the oil pump, I’m making a detour on the project. I’m going to pull the crankshaft to inspect the main bearings. I suspect I won’t like what I find there either, but it makes sense to take a look.