Yes, it is possible to decrease the larger pulley diameter. However, you may have to change the idler pulley arm length and go with a shorter belt to ensure belt engagement.
If it was me, I would see if I can increase the governed RPM or throttle stops first to see if there is any improvement in performance. This is a cheap mod and you can always reverse it if it doesn't work out.
This message was modified Feb 24, 2010 by aa335
