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

Notices

Closed Thread
 
Thread Tools Display Modes
  #1  
Old 05-15-2011, 01:06 AM
jrmints1415's Avatar
jrmints1415 jrmints1415 is offline
Senior Member
 
Join Date: Jan 2011
Location: Naperville Illinois
Posts: 571
Thanks: 14
Thanked 26 Times in 20 Posts
Default Jackshaft gear ratio

How does this ratio sound? 12 tooth to 18 tooth to 13 tooth to 60 tooth? I have 20 inch tires. What speed would i get with a degoverned engine??
__________________
Whats better... the ride or the build???
  #2  
Old 05-15-2011, 08:00 AM
amcjavelin amcjavelin is offline
amcjavelin
 
Join Date: Mar 2011
Location: western maine
Posts: 86
Thanks: 0
Thanked 0 Times in 0 Posts
Default

need to use the sprocket ratio calculator plus figuire in the size of rear tire and also top rpm that the engine will be allowed to run at
  #3  
Old 05-15-2011, 08:55 AM
r97's Avatar
r97 r97 is offline
Measure twice cut once
 
Join Date: Jul 2010
Location: Massachusetts, USA
Posts: 3,790
Thanks: 40
Thanked 236 Times in 222 Posts
Default

i suppose i would say its a little steep for a 6.5hp, but should work pretty good on flat ground.
__________________
Slow and steady wins the race, right? I'll get there eventually.
  #4  
Old 05-15-2011, 09:17 AM
Bluethunder3320's Avatar
Bluethunder3320 Bluethunder3320 is offline
Senior Member
 
Join Date: Sep 2010
Posts: 5,682
Thanks: 516
Thanked 185 Times in 166 Posts
Default

on my bike project (the current one....) ive got 12t clutch, 13t jackshaft to 18t, to 50t...... sort of the reverse that you have, but i knew that putting the 18t first would be too high.
  #5  
Old 05-15-2011, 09:20 AM
jrmints1415's Avatar
jrmints1415 jrmints1415 is offline
Senior Member
 
Join Date: Jan 2011
Location: Naperville Illinois
Posts: 571
Thanks: 14
Thanked 26 Times in 20 Posts
Default

yea i got the same kit you did. should i use the 13 toth first? How fast would i go? What would be my final gear ratio?
__________________
Whats better... the ride or the build???
  #6  
Old 05-15-2011, 09:22 AM
Bluethunder3320's Avatar
Bluethunder3320 Bluethunder3320 is offline
Senior Member
 
Join Date: Sep 2010
Posts: 5,682
Thanks: 516
Thanked 185 Times in 166 Posts
Default

you could always try it both ways. i am not sure how to figure out a ratio with a jackshaft, but i knew i was close anyways...
  #7  
Old 05-15-2011, 09:29 AM
jrmints1415's Avatar
jrmints1415 jrmints1415 is offline
Senior Member
 
Join Date: Jan 2011
Location: Naperville Illinois
Posts: 571
Thanks: 14
Thanked 26 Times in 20 Posts
Default

toy story where are u!
__________________
Whats better... the ride or the build???
  #8  
Old 05-15-2011, 10:04 AM
r97's Avatar
r97 r97 is offline
Measure twice cut once
 
Join Date: Jul 2010
Location: Massachusetts, USA
Posts: 3,790
Thanks: 40
Thanked 236 Times in 222 Posts
Default

/ = dived
* = multiply

jack shaft input / clutch sprocket * axle sprocket / jack shaft output = overall ratio

max engine rpm / overall ratio = rpm of axle

circumfrance of rear wheel (for example, in inches) * rpm of axle = inches of vehicle travel per minute.

inches of vehicle travel per minute / 12 = feet of travel per minute

feet of travel per minute / 5280 = miles of travel per minute

miles of travel per minute * 60 = miles per hour

__________________________________________________

example:

20 teeth on jack shaft input / 10 teeth on clutch = 2
45 teeth on axle / 10 teeth on jack shaft output = 4.5

2*4.5 = 9:1 overall ratio

3600 rpm / 9 = 400 rpm axle speed

11.5" tire DIA * pi = 36" tire circumfrance

36" circumfrance * 400 axle rpm = 14400 inches per minute of vehicle travel

14400 ipm / 12 inches (there are 12" in a foot) = 1200 feet per minute

1200 fpm / 5280 (5280 feet = 1 mile) = 0.22727272727272727272727272727273 miles per minute

0.22727272727272727272727272727273 mpm * 60 (60 min = 1hr) = about 13.63 MPH

__________________________________________________ ___________
if you want you can just find the overall ratio and plug that into the calculator.
__________________________________________________ _________

to answer your question, having he 13t first would make about a 3.6:1 overall ratio, not good.
__________________
Slow and steady wins the race, right? I'll get there eventually.
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 01:38 AM.


Powered by vBulletin® Version 3.8.4
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.