I have a 81 RM250X and the engine number is RM250 - 10120. If I'm reading the list of engine numbers correctly this belongs to a 76 RM250A but it is definitely an X the clutch arm, crank case , cylinder and reed are all X. I know the X has a problem with the main bearings chewing out the cases and I wonder if someone has done something fancy to get around it.
Or am I a Twat, that's reading the engine number list wrong ?
Any help would be greatly appreciated.