how long is a piece of string?

there are too many variables to consider to guestimate an accurate top speed!
what engine? is it leaned right out so it revs? what pipe? what fuel? what length header(this affects top RPM)? what type of tyres? tyre circumference? spur gear & clutchbell sizes? these are a few of the most important variables to consider[X(]


but as a rough guess, say about 40 MPH!