Help with carb size?

[hank22]

I recently bought my 250r and am having problems with the carb. This is my first R and 2-stroke at that. I forgot to ask the seller which carb is on the bike. It's got a 310 kit, and i'm having a little trouble with the carb now. I'm wondering what size carb i got if i should even work on it or if i need to buy a bigger one anyways? The carb is a Keihin PJ 07BWBK. Anyone know which carb this exactly is?

[Honda 250r 001]

well if i had to guess, i would say its stock. which is defeneatly too small. You need AT LEAST a 36 for bare bottom end performance. and a 39 for pure top end performance. the 38 airstryker would be a very good choice and there are a few on sale for cheap on here too.

[wilkin250r]

Someone can correct me if I'm wrong, but I don't think the carb size is encoded in the serial number an any way. The only way to determine the size is to measure it. Measure the small opening, the inside diameter is your carb size. Calipers work best, but you could probably approximate it with a ruler or tape measure. Even if you don't get exact with a ruler, you would certainly be able to tell the difference between a 35mm and a 37mm.

[1promodfan]

Originally posted by wilkin250r
Someone can correct me if I'm wrong, but I don't think the carb size is encoded in the serial number an any way. The only way to determine the size is to measure it. Measure the small opening, the inside diameter is your carb size. Calipers work best, but you could probably approximate it with a ruler or tape measure. Even if you don't get exact with a ruler, you would certainly be able to tell the difference between a 35mm and a 37mm.

I'm not saying you're wrong, but I think some carbs. can be identified by the numbers stamped on the carb. I know thats how I found out what I had (via the Keihin web-site). That being said, I don't think you can identify all carbs. that way.

[hank22]

Thanks for the help guys, i'll try to measure it to see what i can find out. I tried to look on Keihin's website but couldn't find anything about mine by the number on their site. So i'll measure it and go from there. If it's stock i'm goin to buy a bigger carb rather than try to fix this one. Anyone knows anything else about my carb by the numbers on it let me know, thanks.

[hank22]

Thanks for the help guys! i measured it.... def was a 34mm stock. Going to buy a 38 A/S, seems to be what everyone suggests for what i have done to it. Now i got to figure out the jetting for the new one!