I recently became the owner of what I think is a and#39;70 Cota. Its in fairly decent shape and I think a previous owner was refurbishing it a bit. They were doing an ok job but a but were lacking in some of the details.
The engine wasn't turning over at all. I assumed it was going to be a stuck piston from sitting. I have no idea how long it had been sitting. I pulled the head to find a brand new Tarabusi piston in the bore. I then pulled the engine covers off to see if something was amiss. No problems there. I then put a wrench on the crank nut and was able to turn the engine over with some difficultly, once it reach the upper half of the stroke it turned easily. I then removed the cylinder and the cranked turned easily. Nothing in the bore to cause any problems. Put the cylinder back on (didn't bolt it down) and the engine turned easily through the entire stroke. Put the bolts in, tightened them up evenly in increments and again the crank wouldn't turn. Loosen the bolts and it turns. At that point I needed to call it a day.
Will be getting back to it again but does anybody have any ideas? Been going over it in my head but haveing a hard time thinking of a reason why this might be happening. This is my first Montesa. I have had a couple Bultacos and an Ossa.
Thanks