I am starting an MK indy build with fireblade powerplant.
Can anyone help me as to which ratio diff is best.
When i worked out top speed with 3.38 diff and 205/55 15 tyres it was doing 185mph at 12000rpm.
mmmm thing i did that wrong.

looking for best accel top speed of around 100mph will do.

i run a 3.89 diff, 15" 60 profile tyres, high 120's mph on 12600 rev limit, blade box.....does that help......?

i find that to be about rite, pretty much just under 1000rpm per 10mph in top, if you geared for 100mph max IMO you would get fed up of the noise whilst cruising at 80ish, and the back end would be all over in the lower gears.

Remember that there is a primary reduction between a bike engine and its gearbox, the output shaft never turns at the maximum engine revs.
Paul.

quote:

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When i worked out top speed with 3.38 diff and 205/55 15 tyres it was doing 185mph at 12000rpm.
mmmm thing i did that wrong.

looking for best accel top speed of around 100mph will do.

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Thanks jon


for paulf

primary reduction forgot about that.
(didnt even know about it, shows how thick i am)
any idea what it is on a blade?

I think the primary ratio is about 1.5-1.
I have a 3.89 diff in my car and intend to eventually fit a blade engine, but was thinking along the lines of changing to a 3.54 diff to allow me to keep 13 inch rubber.

quote:

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Thanks jon


for paulf

primary reduction forgot about that.
(didnt even know about it, shows how thick i am)
any idea what it is on a blade?

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Thanks paul

Have found out that it is 1.52 and have created a spead sheet to work out speeds.

Will email u sheet. (is a little untidy at moment but works ok)

Sorry I did'nt spot this thread.

(I asked the same question in another one)

Could you e-mail me that spreadsheet Tony?

I'm also building an MK with Blade.