25t engine sprocket 36t clutch. 32t trans 70t rear = 3.15 final ratio
31t trans. = 3.25 final ratio
30t trans. = 3.36 final ratio
All this with my stock 5 speed. With .21 change on a 30 t anybody remember RPM @ 75 mph Not going to be much of a long distance bike anymore as I have a newer one for that. Just a hot rod.
Working on swing arm now but want to make sure I can always use a HD belt
Thanks.
Hopefully I can go with a 6 speed later

 

the load on the belt goes way up when you gear down maybe 2 times what it was

MPH from final drive ratio

rpmX60
-------------------------------------------------
final drive ratio x tire revolutions per mile

5200 X 60
---------------------------------------
3.37 X 775.69 < revolutions per mile

312000
-------------
2614.08

= 119.35

 

Thanks for the final part to the math John. Helped a bunch as I don't do it much anymore....
Now to figure if I should trust the belt or just run a chain. Seems about 8 mph difference at 5200 from 3.15 to 3.37

 

anything making over 100 100 on the dyno we gun shots when we load the bike during testing one gear 4th only < the gun shots are the belt jumping over the pulley to another tooth

if you have never heard it before and after the change you dont hear it, your good to go, the ramp up speed of torque is at a different plane - its all in the mechanics of the parts and how they like each other i guess

my buell S2 thunder bolt has a copy of the motor we road raced with my son has one as well and his has a chain / mine has a belt < fibreglass reinforced kevlor - his is jerky at low engine speeds and much more in your hands in vibes - mine with the belt the harmonics are way less and more a rider with crazy power

have not broken a belt but i really dont go anyplace with it as i have a pile of machines, i am going to put it back on the road this year its been 3 since i drove it last

 

http://www.bigboyzheadporting.com/Gearratio.htm

 

Not following your math for revolutions per mile.
A 1998 FLHTCUI uses a tire sized MT90B16, which has an overall diameter of 25.70". My calculation of revolutions per mile is: 784.75
What tire are you basing your calculations on?

 

For what I wanted close is good enuff. I was looking for the spread not the actual numbers. I'll have to go plug the 170/60/17 in for final number later... Looked its 25.03. .7% change
Thank for thinking of it.

 

I have heard the gunshot/ slap slip. This one will push some respectable numbers More than 155 hp I am sure with gobs of torque as its cammed and other stuff to be a 2200-5800 stump puller. Plus it got a 15 hp shot of juice when done. Guess with a chain I could stuff more tire in it with out cutting the frame or swing arm. ( already need a little more room in frame for heads) Wanted to run the 170/60/17 rear wheel in a 08 swing arm. Not much on burnouts.....more of a roll on throttle in 3rd. Guess I got to break it to find out. How much HP on your builds do u run thru a belt?

 

Calculator.
I don't know if this will help you any, but here it is

 

I'm running 3.36 with a Baker OD6, have had a Screamin Eagle side car belt on it for a long time. First engine was around 150 with the bumped up compression and noticed the primary chain stretched more than the belt. That belt is a tough son of a biiiiatch, don't do throttle whacks but it sees a lot of throttle roll ons.