Increase belt size for higher top speed?

[AveCat]

What belt size can I go to to increase my top speed?

Spree NQ50

[patthesoundguy]

I've done it and I'm pretty much one of the only ones who has been successfull with the belt change out to the 1/2" wide belt. I'll have to go look at the size. It was first thought to be an AX24 but it was too long. I think it was AX23 that fit. But... Remember when ever you change the gear ratio you loose bottom end take off. If you have a ton of miles on your stock spree and it has horrible compression it will be total junk in the low end. And a word of caution... Installing the belt is extremely difficult and you run the risk of stripped crank threads and or splines. Do at your own risk!!!!!!!
That being said you will see a top end gain of 4 to 5mph in top end. I had the big bore kit with pipe so I had decent bottom end and decent top end for a spree motor that is. Stiffer clutch springs along with tighter squish and better compression will help as well. (84/85 head with 86/87 piston)