My bike revs out too far on the long straights but at the same time, that doesn't equate to much actual top speed.

Neal shared some info on his 21 sprocketing with me for the same track I am at this weekend. (His times are fast so I rate he is a good source for info). Stuck that into a gearing calculator along with the two bikes box ratios to try and come up with some sprocketing for the 28.

The calcs tell me to run a 15/41 combination. Anyone run this sort of gearing or have any input on it.
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If you want a proper 2 stroke get an RGV.

I ran a 42 rear on my MC21 for the track, livens up the acceleration and I don't think I ever found full top speed anywhere.

Saying that, I've never ridden it at Donnington...
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball

The 28's stock is 15/44 so it is already pretty low gearing.
I'm in top gear and at peak power just over half way down my regular track's back straight, By the time I get to the braking point I'm well into the red and waiting for the thing to blow up or run lean.

Next question, are the 21 and 28 sprockets the same?
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If you want a proper 2 stroke get an RGV.

Front sprocket? Yes. Rear? No. And neither is the gearbox or primary drive ratio.

I ran 15/39 on my '28 (which I believe was totally 28se) and it was flat out by the Dunlop Bridge.

I ran 15/40 on my mc18 (unknown box, but as it's a dry clutch, probably a '21) and was flat out about 2/3rds of the way along the "straight" between Church and Rocket at Anglesey, swapped the front to a 16 and instantly went 4 seconds a lap faster
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Please do not PM me technical questions, if you can't find it on the Forum start a thread

fontyyy wrote:Front sprocket? Yes. Rear? No. And neither is the gearbox or primary drive ratio.

Thanks, I do realise the boxes are different and calculated as such.
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If you want a proper 2 stroke get an RGV.

Howzit , go I have a 16 front srocket if you want to try it !At Phakisa , you want to come onto the backstraight in 4th changing into 5th , 6th should rev out as you hit the apex of the right hander . You hold it flat out in 6 th gear and the two corners bcome one . Watch out for the ripples on the exit of the corner , have fun !Neal

I ran a 16t once
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If I have to take the carbs off once more...

Well done Stephen....

Neal wrote:Howzit , go I have a 16 front srocket if you want to try it !At Phakisa , you want to come onto the backstraight in 4th changing into 5th , 6th should rev out as you hit the apex of the right hander . You hold it flat out in 6 th gear and the two corners bcome one . Watch out for the ripples on the exit of the corner , have fun !Neal

16 sounds like a good fix since I might not be able to get rears cut before the weekend.
I'll take your word on hitting that 6th gear flat out I'll walk before I run thanks.
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If you want a proper 2 stroke get an RGV.