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What Carb?
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Posted by: baker250r

ok... i am running goona be running longrod with a 86 piston... and spacer plate... i got paul turner full exhaust... and goona be runnin cr250 boysen rad valve with reed spacer.... what carburetor will be better for me? stock, or 38mm? ive heard that bigger carbs are for top end and stuff. and i want a bottom, midrange monstor for MX. if i get a 38mm, do u recommend getting a cr250 carb? or gettin a kehein, the cylinder is also ported and polished

Posted by: racerx573

38mm Airstryker will suit you just fine. I had that on my old 265 engine. It had a Turner pipe as well, and V-force intake, it was a beast to say the least, and was easy to jet.. I now run a 39mm on my 265 Powervalve.

Posted by: beak7707

I have never ran an Airstryker but many people have and still do, so I'm sure its a good carb. But I would highly recommend the mikuni TMX carb. I have the 36mm on my stock motor R and raced XC and loved it. The throtle response and the lowend power was night and day over the stock carb. I got mine from ESR and it came prejetted ready to bolt on. It also came with a jet board with probaby 6-10 other jets if you ever mod you motor anymore.

Posted by: wilkin250r

Carburetors are not "top end" and "bottom end" the same way that pipes and porting are. A top-end pipe will have very poor low-end power, you actually, physically have less power in the lower RPM range. The trade-off is top end power for low end power.

A top-end carb will not physically have less power at low RPMs (unless it's jetted improperly). The trade-off is top end power for throttle response. Now, throttle response will FEEL like low-end power, because you'll have instant power off the line and out of corners.

Let's paint a scenario. You and your buddy are riding on identical machines, except for carb size. He has a 36mm, you have a 38mm. You're cruising along just above idle, and you both whip the throttle wide open. HIS machine, with the smaller carb, will respond instantly and take off. Your machine will stumble for a fraction of a second, then take off, but by this time, your buddy is already a quad length ahead of you, because he got faster throttle response.

For racing MX, throttle response is more important than top-end horsepower. If you're running the stock bore, or a 265, I'd suggest a 36mm, either the TMX or Air Stryker.

Posted by: MyKe2g3

Get the 38 mm a/s because if your like any of us you wont keep the bore stock on it for long. It will also save you on the long run if you ever decide to go big bore also. A properly tuned carb is hard to beat and imo the a/s is hard to beat for the 250r.