I've just fitted a second hand flat bashplate to my 03 SY250. It's in good condition and came complete with the four allen head mounting bolts and nuts and it was considerably cheaper than a new one.
It came off a later model SY 250, a 04 or 05 model
Fitting it correctly was a bit harder than anticipated and I have two questions:
It only just misses (about 1 or 2mm at the closest point) the crankcase where the bolt connecting the magneto cover is at the lower front of the motor. In order to get this gap I had to tighten the rear bashplate mounting bolts first and then do up the front ones. Doing it in any other order resulted in the plate touching the crankcase. Is the 2mm clearance normal/sufficient? I can't imagine the plate moving or flexing and the original bashplate almost touched the crankcase at the same point anyway.
The plate being 6mm thick is quite stiff and in order to screw it to the front mounts I first had to insert a longer bolt on one side and tighten it so I could then get the plate closer enough to the engine/bashplate mount to use the correct mounting bolt on the other side, tighten that up and then screw up the other side. I think I had to pull it in about 3cms. The front bashplate mounting holes are a vertical slot and when pulling in the plate the bolt starts at the top of the slot and ends up at the bottom, so it looks like that's what had to be done. With the thickness/stiffness of the plate there was a fair bit of tension required to screw the bashplate into position. Is that mounting procedure and tension in the bashplate when it's in position normal? The plate is not twisted or bent and when installed it is flat on the bottom.
I had to extend the oil drain plug hole towards the front slightly so I could access the drain plug which has an allen key head without removing the bashplate. No worries, easy to do and negates the need to remove the plate for anything!
The standard rubber block that sits between the between the plate and the bottom of the crankcase is in place.
Cheers