I took on a project for a friends brother this past winter. He has a 76 R90/6 that needs a 'bit' of TLC. I am beginning to think I'm in over my head. What I thought would be a simple tune up, new tires, clean up, etc, has turned into a full blown 'tear it down and fix this miserable thing'. Thing is, I've never done something this extensive before.
There was so much oil caked on to the cylinder fins and under the push rod tubes, that I thought the tube seals needed to be replaced. I cleaned up the bike as much as I could, then rolled it back into the garage and started taking things apart. I pulled the exhaust off (its all rusted and pitted), and then pulled the heads and cylinders off. Now I'm treading into new territory here. I've never partially dismantled an engine before.
I find that the tube seals are just fine, but there is no O ring between the case and the cylinder. hmmm.....
These went to the local shop to be cleaned up:
The pistons were caked with crud:
I cleaned those up myself last week, today I pulled them out and ran them through the solvent tank.
Because I'm new at this, I don't quite know why the pistons and such are like this. Needs rings? Carbs not adjusted properly???? I have read that the piston rings should have the gaps staggered, but on both sides, the larger of the three had the gap at the top (as in the picture), and the other two were almost lined up together at the bottom. Is that part of the problem, or ??? Any advice would be appreciated. I want to put this thing back together and get it out of my garage.