Sprocket Advice Needed!

[AZUSA]

Hey,
Im in the process of building a mini bike on an azusa 5" wheel frame, using a predator 212cc. I need some help on figuring out the right sprocket ratio that will allow me to achieve speeds around 40 MPH.
Thanks

 

[bob58o]

5" wheels, but what size tires? I'm sick and too tired to put in the grunt work today.
Stock engine? Governor or No governor?

 

[Randy H]

There is a speed calculator on the home page of diygokarts.com

Have some soup Bob.

 

[bob58o]

There is a speed calculator on the home page of diygokarts.com

Have some soup Bob.

But I'm using my kitchen table as a paint booth stand at the moment.

 

[Randy H]

But I'm using my kitchen table as a paint booth stand at the moment.

Well you've got your priorities established. Any good man will appreciate that. Women not so much.

An apartment machine shop is a lot like a vow of celibacy, like the vows of my father and his before him,

 

[Hellion]

Hey,
Im in the process of building a mini bike on an azusa 5" wheel frame, using a predator 212cc. I need some help on figuring out the right sprocket ratio that will allow me to achieve speeds around 40 MPH.
Thanks

Are you gonna "straight-chain" it, use a jack shaft (which means two chains) or do a jack shaft in conjunction with a Torq-A-Verter?

A straight chain (from clutch straight to rear sprocket) can work but it just won't have the low down grunt and will take a while to get up to 40.

 

[itsid]

An apartment machine shop is a lot like a vow of celibacy, like the vows of my father and his before him,

without weight, tyre size and engine rpms it's nothing but guesswork.
As Hellion said it might.. but it also might just not work

And as bob said:
tell us, or we can't help you really.

'sid

PS if you want to punch in the numbers on your own, try app.kartcalc.net from your mobile device.

 

[bob58o]

4.10x 3.50-5" Tires
so 12" tires.
3.14' traveled per axle revolution.

I would remove the governor and use a 30 series torque converter with 6" Driven Pulley.
Gear it 5:1
10T #41/#420 on TC, 50T #41/#420 on Rear
or 12T #35 on TC, 60T #35 on the rear

40mph at 5000 RPM

---------- Post added at 02:51 PM ---------- Previous post was at 02:40 PM ----------

Without the Torque Converter,
would need to still remove the governor and gear it 4.5: 1
45:10 or 54:12

No TC, with a governor... 3.2:1, no bueno.
TC, with a governor... 3.6:1, might work.