Somebody help me out.

I am not sure about how carburator mods work on 4-stroke motors.
Basically;
1) What does the size have to do with performance? i.e. 27mm, 34mm, etc...
2) Is it wise to increase size with a stock motor? Any gains, benefits, pit-falls?
3) Case Study: What if I replaced a 27mm carb with a 34mm carb?

Reason for asking, I need a new carburator for my ATC 250SX. Rather than put a stock carb back on it, I am curious if there is something to gain by swapping for a better set-up. I do plan on modifying the engine at a later date and a K&N filter will be put on real soon.

Thanks.

 

A slightly larger carb will help Honda typically undercarbs their quads. For your application I would try to find a carb from a 300ex. Going too large will cause poor low speed performance. I f you were to add a pipe, cam, and piston a little larger carb would really help.

 

Air,

What size is a 300ex? What about a 34mm from an ATC 350x?

Thanks.

 

A stock 300EX carb is a 32mm Keihin.