The SR was fitted with about 3 different engines, your 1st problem is to find out which SR engine you have 1st
Second that ^^ Also different types eg Ditech so wont be simple if its one of those. Also youll have odd sized wheels. Like 13 rear and 10 on the front with a pizza tyre.
depends wat engine you have as aprilai's were fitted with minarelli engines piaggio engines... so if its a piaggio one it may fot it will have to be aircooled aswell