Short answer is that if you go too big you lose the pressure drop in the carb throat that draws fuel into the airstream. Otherwise, bikes would all have massive carb throats as there would be no downside. Smaller throats mean better metering of fuel and better atomization.
Unless you have done some substantial work to your bike to make a LOT more power at the very top end of the engine's rev range, you'll only hurt the bike's throttle response and fuel economy by making a sizable upward jump in carb throat size.
| 1990 Kawasaki Zephyr 615 (Daphne) -=- 1986 Kawa Ninja 250 (stolen) |
| The Motorcycle Fuel Injection Handbook -=-
http://tinyurl.com/297abo |
