I have been working quite a lot on the Ok Supreme. My first plan with the engine was to overhaul the magneto and check the cylinder and head. I wanted to leave the bottom halve alone.
But it is not supposed to be easy, so when I saw the state of the cylinder and head I knew that the crank cases had to be opened…..
The engine has not the usual main bearing set up of ball and rollers. There are long rollers straight on the shafts. So when you have worn shafts……you have trouble…..
The shafts has too much damage for grinding and “spray” welding don`t work well with rollers. New shafts are the only solution.
The JAP speedway engines have the same set up but not the same size…..So where can I find new shafts? A Swedish friend pointed me in the right direction…..There was a place that could help…..After a phone call we agreed that I took the crank apart and sent the shafts and bearing rings to get the everything to the right sizes.
Need some pressure to keep the crankshaft in place when unscrewing the big end nuts.
There were more problems…….The rollers of the big end bearing had “eaten” a 3mm groove in both sides of the crank weights…..Another phone call and everything are on their way to Sweden.