Tom, one tip the manuals never tell you with this type dyno is to never use the bike's brakes to slow it down after a run, it will fry the brakes in seconds. Lots of Dynojet operators have learned this lesson the hard way.
This dyno has no brake! Allowing it to slow down on its own takes about 3 minutes, which incidentally is how I performed the coast down test to determine rear wheel, chain, and bearing drag. As a result, I have to use the bikes brake to slow it down as gently as I can. So if the rear brakes wear out, I don't really need them anyway.
Also, it is imperative to tie the bike down in both directions... And don't try to bump start the motor from the speed after the run.
Like transporting a bike in a trailer or on a truck, I always tie the bike down with 4 straps. On the rear wheel, the tie downs don't want to be too tight and the tire pressure needs to be at the upper limit of their rating to prevent excessive drag.
Tom could you take the Yam to another Dyno get some results then fiddle with the software to replicate it.
Good advice on overrun from the roller you will need to be careful with the BSA gearbox,i usually pull the clutch and use the dyno's brake to slow down then select neutral once stopped.
Andy, I could test one of the bikes on another dyno, but the dyno guy I used before (Dan Dunn) has left the area. By using the Yamaha factory rating, I should get some "happy horsepower" numbers anyway. And as for not downshifting while the wheel is spinning, I think I've already learned the dangers of that - - twice! Remember my infamous transmission swap at Bonneville last year?
Drag chute won't do?
Good idea Jack. But I haven't figured out how to get the dyno moving fast enough to make that work! Although the wheel did slow down a bit faster when the tail end of one of the tie-down straps got caught in the rear wheel.
Tom