keihin oval slide vs round slide, pros, cons, ???

[Deathrocket]

So I bought a used 38mm round slide keihin carb for my 81 250r to replace my oval slide keihin with issues. my question is is whats the difference? what makes one better than the other?

[Red Rider]

The round slide carb worked best for top end power, but it's throttle response was a little slow. The oval, or flat slide, carb produced excellent throttle response, and okay top end power. The manufacturers felt that throttle response was more important than top end power, since most riders spent only a fraction of their time at top end power. These days, the latest thing is a "D-slide" carb. The "D" shaped slide combines the desired attributes of both round & flat slide carbs.

[Deathrocket]

ok i am running a 2 stroke, so how slow can throttle response be? lol also what about fuel economy? I got this thing in good shape off of ebay for $28 shipped so I am willing to try it.. anything else the round slide carb does better or worse?

[Red Rider]

According to the '81 250R spec sheets, on the forum here, your 250R came from the factory with a 27mm round slide carb. I don't know if you can trust that data though, since the data on the 85-86 250R's is wrong, but it sounds like it's in the ballpark. Personally, I don't think you'll notice much difference in the throttle response going from a flat slide carb to a round slide. I don't know what size flat slide carb you're replacing, but if it was smaller, you might notice slightly less bottom end power with the new carb. Basically, the bigger the carb, the better it flows at high rpms, or top end power, with a slight loss of power on the bottom end. Good luck.