Yet more questions - Chain Drive Mod.

[Thom]

Right! Im back, yet again!

Atleast I keep you all on your toes!

Well, basically my bike seems to be derestricted, and i'm not really a fan of doing much more than 80-85mph, so i'm thinking, why not convert the extra 15mph i'm not using, into accelleration?

Now, if my years of mountain biking are anything to go by, by changing the front/rear cogs to ones with fewer teeth and a smaller diameter i should be able to get away from the mark quicker.

Does anybody have an idea of how i might find out how many teeth on each sprocket i would need?

Would there be a graph produced somewhere showing top speed/accell correlations?

Finally, has anybody done this?!

[Phil_P]

To increase acceleration at the expense of top speed, you need to reduce the size of the engine sprocket and/or increase the size of the rear wheel sprocket.

The amount you change will be up to you. Bear in mind that changing the engine sprocket by one tooth has roughly the effect of changing the rear by two teeth.
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It is not enough to win, others must fail.
Moto Guzzi 1100 Sport Injection '96

[hmmmnz]

what bike are we talking about??
i would drop one tooth on the front or add 2 on the back
that should be about right
wemoto sell pritty much all bike sprocket less 1or 2 teeth
____________________
the humans are dead
I kick arse for the lord
Wiring Diagrams BIDNIP it bitches

[hmmmnz]

phill beat me to it
____________________
the humans are dead
I kick arse for the lord
Wiring Diagrams BIDNIP it bitches

[G]

As above, but note on an 'average' 15 / 45 tooth setup, it will be 1 tooth on the front is the same as 3 on the rear.

You should be able to work out the ratios and how that will effect your top speed. People have made programs and spreadsheets to do this for you.

If you go up/down the same amount on each sprocket you won't need to change the size of your chain.

Remember, if you lose that 15mph top speed, sitting at or near your top speed you will be cruising at high rpm, which often isn't ideal.

[Thom]

well right into the redline the bikes supposidly capable of just over 100mph.

Sooo, i plan to maybe have a top speed of 90mph so that it gives me 20mph leeway for the legal speed limit.

thanks for the advice guys

oh by the way its a honda nsr 125r, 1990 spec bike with a 99 foxeye engine.

[ms51ves3]

Don't forget aswell that you will lose some fuel economy. I'd leave it how it is if I was you. Honda made the sprockets that size for a reason.

Mark

[salty21]

im currently running on a 12 tooth front and a 36 rear
that front -2
rear standard
top speed= 85 at the redline
acceleration=not sur on 0-60 but quick enough about 6.5 i think

personnaly i wouldnt advise 12 on the front as the chain rubs on the chain guide and makes a funny noise lol so i would say 13 front and 38 rear if you can find em
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04 NSR 125(sold) ---- 03 CBR 600rr(sold) ----90 pan euro ST1100 '' ----02 CG 125
94 CB400 Super Four ---- 2000 VTR SP1 (sold) ---- 08 ninja p8f(sold, meh) ----05 CBR600rr

[G]

I'm not sure you'll improve the NSR much - if you use the clutch in first you still get acceptable acceleration.

Yes, fouth gear might accelerate better, but change it by a reasonable amount and now it's just the same as third gear was.
Ok, so maybe you've changed the ratios so they're better suited to some conditions, but other conditions your gearing will now be out a bit more.

Overall acceleration will be slightly improved as you're gears are overall a shorter ratio, but not by much I expect.

[ncrn]

[salty21]

where did u get the +3 rear from?
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04 NSR 125(sold) ---- 03 CBR 600rr(sold) ----90 pan euro ST1100 '' ----02 CG 125
94 CB400 Super Four ---- 2000 VTR SP1 (sold) ---- 08 ninja p8f(sold, meh) ----05 CBR600rr

[G]

B & C are worth a shout (err, think it's them anyway). They did me a reasonable price on a custom made rear sprocket for my CRM125.

They then called me up a bit later and offered me another sprocket for it at their cost price (or so they told me ) because someone had cancelled an order.