Gearbox ratios ST2

[Paul James]

Odd one this...my'98 ST2 fitted with 15 tooth front and 42 tooth rear sprocket revs too much (about 85mph @6,000rpm).

I've fitted a 39 tooth rear sprocket and it now runs just under 100mph @ 6,000 rpm.

The later bikes run 15/42 sprockets but seem to do around 100mph @ 6,000.

Anyone got the gerarbox and primary drive ratios for an early ST2 ?. Must be a change in the gearbox and my guess is it's the primary drive ratio that's been altered as it would be a real pain to change all the gearbox ratios.

[ST4]

My 1999 ST4 does 80mph for 5000 rpm on standard sprockets and with a 14 tooth front this goes up to about 5750. I dont think my ST2 (1998) that i used to have would do 100mph for 6000 rpm though, at 80mph it was the same 5000 rpm as the ST4.

Probably no help to whatsoever though!

Paul.

[nelly]

There doesn't appear to be any changes to the primary gearing from what I can find Paul.
The ST4 runs different primary ratios, so that explains that one.
Only thing that could make a "significant" difference is the tyre profiles etc. ie, the new Diablos are quite a tall tyre, visibly more than my old 010's.......
Don't the later bikes run a 180?