There are cheaper RNV's, but I'd highly recommend a Jett Universal RNV. The threads are pretty fine, so small adjustments are easy.


http://www.jettengineering.com/accy/accy.html

$25-$35 depending on which one you get.

This is of course if you want to use a RNV. If not, you will need to modify the carb thats on it or get a different carb....