Diffference between round and flat slide carbs??

[two85atc250r's]

What's the difference between round and flat(or oval) slide carbs besides for the obvious way they look? Do they perform any differently? Is one or the other better for the R?

[wilkin250r]

The reasons get kinda complex, it has to do with turbulence at the jet, but I won't bore you with all the stupid details.

As a general rule, flat-slide is better. It gives you better airflow characteristics, which shows up most promintenly in throttle response, but also shows up in other areas as well.

Flatslide carbs have better throttle response than round slide carbs.

This also holds true for the in-between carb types, like oval-slide or D-slide carbs. The flatter the slide, the better the throttle response.

[two85atc250r's]

Thanks wilkin, I appreciate it. Now I know, and knowledge is power! I have a couple old keihins laying around but they are round slide PE's and I didn't know if they were any good or not.