Hi my names Andy, 25 from England. I recently had the idea of buying an old ish rm250 and doing it up. I found a 98 rm250 in good condition, but it needed a new piston as the old one had broken up and left half it's skirt in the crank case in 1000's of little pieces. When I picked the bike up the cylinder was already removed. The seller told me the bike was a 98, but the engine was a 99. He also have me a spare empty crankcase which he said was a 98. so now I have the bike, yesterday I got the motor out while I had a quite few moments at work. Once I was ready to go home I went to just place the cylinder and head on the case just for the sake of it. It didn't fit! Strangely though the cylinder does fit the spare cases. The problem I have is I don't know what year cylinder I need to buy as I don't know what year my bottom end is. Even if I find out used cylinders from these bikes of this age are almost impossible to find. Do I find another cylinder or do I transfer all the internals from my bottom end into my spare cases, as I know I have a cylinder that fits? Here's an image of my cases, if anyone could help me with the years? Many thanks!