Carb Question?

[4LEAFCLOVER]

What's the difference in size on the carberators got to do with performance to a quad. Like FCR 39mm, and FCR 40mm for instance. I'm also wondering what is the size on a stock 2005 450R and if I wanted to change it out, what would be the best size to go with. And when you change this out on a quad what other fabrications do people usually do?

[OKTRX450R]

Stock for an 04/05 is 42mm...

Now, what changes, you have to get an adapter from someone like Baldwin Racing/Noss machine and wire up the TPS.

What size I think is still up in the air...some guys I know are about to test the FCR bored out to 42mm.