Last time I wrote I knew that the engine didn’t start, but lets focus on the good things; The electrical system seems ok, ignition and fuel pump look also alright, and I haven’t seen any obvious leak. Since then, I’ve also taken the time to check the rear spline and it seems it’s in top condition.
Normally, I stand by the rule that you should always purchase quality tools. However, not being a professional, there are tools I’m a bit hesitant to buy as they will only be used once. One of such tools is a compression gauge. Therefore, at around 35€ I purchased the cheapest one on Amazon, just to get a general impression of the state of the engine. The results were as follows:
|Test (Average of 3 measurements)||Cyl. 1||Cyl. 2||Cyl. 3|
|Without adding oil||75 PSI||0 PSI||150 PSI|
|Adding 5cc of oil to each cyl||100 PSI||0 PSI||160 PSI|
So, found the problem. Cylinder 1 is wounded & 2 is dead, however, cylinder 3 is in spec (140-160 PSI). While I’m here I might also check the valve clearances
The workshop manual states that inlet valves should have a clearance between 0,15 and 0,20 while exhaust valves should have a clearance between 0,25 and 0,30. I measured the following clearances:
|Clearance||Cylinder 1||Cylinder 2||Cylinder 3|
As far as I understand I should change the shims on the exhausts valves of cylinders #1 and #3, but this doesn’t really make any sense if I have to install a new head. Technically I could remove the head with the bike still in the frame, but the engine is so filthy it could use a bit of cleaning. I convinced Álvaro Pérez and Javier Pérez (not brothers) to come by, and in a few hours we had removed the engine, gearbox and final drive from the frame.
After a bit more disassembly later with other buddies that wanted to take part, the engine made it to a fourth floor I can use as a workshop. I started cleaning the engine as I didn’t want a rogue grain of sand damaging anything sensible. Stuck to the engine there was a mix of oil and sand that tinted black anything that it touched.
All screws were removed and placed in bags labeling their position and any gasket residue was quickly removed with scotch brite. Another few days and the head was disassembled, and voila, here is the reason for the low compression on Cylinder 2; a broken valve…
Unfortunately a new set of valves will set me back around 650 euros bought from BMW, however I’m searching for alternatives.
Shout out to Alvaro and Javier who helped with the heavy lifting!