A bigger carb will help any 250. the more mods you have, the bigger the gains.
Keep in mind that a carb inlet doesn't just reflect the size, but also the venturi (the passage inside the carb).obviously if the passage inside the carb is bigger than the one inside the stock carb, it's going to flow more air.
The stock carb is what honda refers to as "22mm piston-valve".
A stock 200x carb is 24mm. a XR200 carb is 26mm. the DG carb for both of those is i believe 27mm.
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2002 250ex- SOLD.
Creator of the 250EX Performance FAQ. For 250ex headwork and various porting , please email me at flyinryanporting@gmail.com