you need to ajust your carb, i assme your putting it onto a stock carb. it will be faster once you get more fuel in the mix. try lowering the clip on the needle.
Read the UNI filter install, same idea. Follow the throttle cable to the carb and unscrew it. Remove the cable to expose the pin. Move the clip down a notch on the pin. Put it all back together.
It will help to have a pair of small needle nose plyers handy.
I was having similar problems in fact with the UNI, today I messed with the air screw and threw in a 60 main jet and wow what a difference, the jet is a must!!