Go Back   DIY Go Kart Forum > Building Plans And Advice > Mini Bikes, Trikes, and Choppers

Notices

Closed Thread
 
Thread Tools Display Modes
  #1  
Old 10-10-2017, 03:37 PM
AZUSA AZUSA is offline
Junior Member
 
Join Date: Oct 2017
Posts: 1
Thanks: 0
Thanked 0 Times in 0 Posts
Default Sprocket Advice Needed!

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
  #2  
Old 10-10-2017, 05:51 PM
bob58o's Avatar
bob58o bob58o is offline
Assistant to the Manager
 
Join Date: Jan 2016
Location: Chicago-town USA
Posts: 7,528
Thanks: 3,232
Thanked 2,256 Times in 1,746 Posts
Default

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?
__________________
There are two types of people. Those who can extrapolate from incomplete data
  #3  
Old 10-10-2017, 07:36 PM
Randy H Randy H is offline
Senior Member
 
Join Date: Oct 2016
Posts: 895
Thanks: 851
Thanked 476 Times in 368 Posts
Default

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

Have some soup Bob.
  #4  
Old 10-10-2017, 08:36 PM
bob58o's Avatar
bob58o bob58o is offline
Assistant to the Manager
 
Join Date: Jan 2016
Location: Chicago-town USA
Posts: 7,528
Thanks: 3,232
Thanked 2,256 Times in 1,746 Posts
Default

Quote:
Originally Posted by Randy H View Post
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.
__________________
There are two types of people. Those who can extrapolate from incomplete data
  #5  
Old 10-10-2017, 09:25 PM
Randy H Randy H is offline
Senior Member
 
Join Date: Oct 2016
Posts: 895
Thanks: 851
Thanked 476 Times in 368 Posts
Default

Quote:
Originally Posted by bob58o View Post
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,
The Following User Says Thank You to Randy H For This Useful Post:
itsid (10-11-2017)
  #6  
Old 10-11-2017, 01:27 AM
Hellion's Avatar
Hellion Hellion is offline
Disc brakes'r for cowards
 
Join Date: May 2016
Location: Location: Location:
Posts: 4,772
Thanks: 1,721
Thanked 1,397 Times in 1,141 Posts
Default

Quote:
Originally Posted by AZUSA View Post
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.
__________________
"I'm just here for the gasoline"
  #7  
Old 10-11-2017, 10:00 AM
itsid's Avatar
itsid itsid is offline
Moderator
 
Join Date: Jul 2013
Location: Ruhrpott [Germany]
Posts: 11,049
Thanks: 1,483
Thanked 4,594 Times in 3,467 Posts
Default

Quote:
Originally Posted by Randy H View Post
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.
__________________
Jokes about german sausage are the wurst.
  #8  
Old 10-11-2017, 01:51 PM
bob58o's Avatar
bob58o bob58o is offline
Assistant to the Manager
 
Join Date: Jan 2016
Location: Chicago-town USA
Posts: 7,528
Thanks: 3,232
Thanked 2,256 Times in 1,746 Posts
Default

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.
__________________
There are two types of people. Those who can extrapolate from incomplete data
Closed Thread

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 02:42 AM.