Top Speeds...ooo errr

[dave higgins]

The primary drive ratio is critical in determining the relationship between engine & gearbox speeds.
If you had those figures you would be able to calculate the exact figure, given that the rest of the info is supplied.

[John Wakefield]

Dave the ratios given for both the Suzuki and the Greeves are OVERALL ratios so take into account both primary and final drive. I think if you check it out my calculations are near the mark, maybe a few revs lower or higher. My point is I dont think the 380 Griffon would safely rev to circa 9000 rpm.
According to Cycle World test on the 380 max bhp was 39@7000 rpm http://www.yeoldecycleshoppe.com/roa...-380-road-test

[dave higgins]

It might rev to 9000 rpm...... but only once.....

[Brian Catt]

A serious ISDT 250 should top out over 80 mph. My OSSA 6DR did this according to the almost accurate speedo, but it was a bit scary! Maybe with tyres upped a bit it might have been OK.