Way back when I had a brain (back in the '60s), I slightly remember that there were formulas not just for drinking but for drive ratios also. Our beloved scooters had both a secondary and a primary drive ratio.

What sprockets do best with a 93" and 5-speed trans. Anybody know how to calculate this?? Strokers do enjoy certain specific tooth counts and before I slap mine together, I wanna make sure. I'm gettin' too old for wrenching and I'll be ducked if anybody else touches her

 

the info you did not provide is the answer

does it have a Front chain or belt drive ( flat side ) ?????? it matters
does it have a drum brake or rear sprocket ?????? it also matters

if you find math not a challenge / or kind of interesting i can give you the formulas and some suggestions -- anybody can do it

 

Yupp ... she's got a front chain and a rear sprocket. Gimme all the math you got.
There was a book out there once by a guy named Bill Denish. It was nothing but pages of math calculations, ratios & everything else.

Thanks!

 

Primary - number of theath on clutch shell - say 37
divide number of teeth on motor sprocket say 24 37 / 24 = 1.54

secondary - teeth on rear wheel sprocket say belt drive 70
By the number of teeth on the trans sprocket say 32 70 / 32 = 2.19

1.54 / 2.19 = 3.37 is the final ratio for that combo late 5 speed evo also has 1993 on 2.94 as the final ratio with changes

MPH from final ratio

RPM X 60 = ( MPH )
----------------------------
final ratio X tire revolitions per mile

Note -- at 3000 RPMs in high gear a standard tire size ( harley 16 inch ) will turn 775.69 revolutions per mile soooo

3000 X 60 = 180,000
------------- -------- = 68.858001 MPH @ 3000 RPMs in high
3.37 X 7775.69 2614.0753

do you need more info ??????























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any number into any number will produce a ratio this is an early evo example i have it in my head as i do this quite a bit ratio changing

 

my eyes just went crossed and my head now hurts

 

5 speeds already have a low first gear in them so with your set up there's 2 ways to figure depending on what you want a street bike or better & smoother highway .

Street I like 22 front with a 47 or 48 rear , shortens the chain a bit and tightens up the OD of everything for a bit more clearance on the hard parts , the change won't chew into things so bad when it loosens up a bit .

Better Highway I ran 23 front and 48 rear , did that on stock 74", 80" and my old 88" , they all pulled fine around town you just had to use the gears instead of lunging it and moved the buzz from 55 to 60 up to around 70mph or a little better & smoothed a lot of the bar & footpeg buzz out too .


This is tried & true time & mileage tested combo's been doing them forever .