Pete
A 13t or 14t should be all you need for a 250cc 5 speed spot on Tony
SHAFTS
BTW this is the difference between a 4 and 5 speed shaft. 5 top 4 lower.The stop plate is 2mm wider on a 4 and theyre welded to the shaft. And the quadrant arm of the 4 has 3 notches, the 5 has 4
To replace the shaft means spliting the cases
Cheers