keihin carb for 250r quest.

[QuadRacer041]

can someone tell me the difference in models of the keihin carbs like PJ, PWK, PWK AIRSTRYKER???????

my motor is being put back together with the following few mods:
full lrd exhaust, 21cc cool head, pro design super cooler, brand new cyl with low to mid range port work donwe by a local shop, and a k&n filter.

i spoke to Nac's racin and the recommended a PJ36mm, what do you guys think????

quad041

[NJ300ex]

Where is there a local shop?

[QuadRacer041]

dr bobs cycle shop,
its on long hill road in oakland.
let me know if you want the #

[Guy400]

Quad041, I was wondering the same thing. I don't know what the difference is in the models because you can get the same size in most of those (i.e., 36mm PJ or a 36mm PWK Airstryker). From doing my own research if you're building your motor for low/mid power than you want to stick with the 36mm. 38mm was suggested for full MX or open trail riding.

Here's there web site, not a whole lot of help but it's something.
http://www.keihin-us.com/

I'm assuming that the PE is their lowest end carb since it runs the round slide and all their other carbs use oval slides or flat slides which are described as being better than the round.

[QuadRacer041]

thanks,
i think ill go with the 36mm but should i get the PJ or the PWK AIRSTRYKER?????
who knows, im goona try to wait a little maybe some other guys can help me out too.

quad041

[NJ300ex]

What kind of work does he do and can he bore?

[rhino99]

I dont know the difference either, but I am running a 36 PJ on mine and it runs awesome. Lots of low end, perfect for MX. I have heard though that the AirStrykers are AWESOME carbs, but Nacs knows what they are talking about, I would listen to them.

[QuadRacer041]

thanks rhino,

yes nj300ex he does boring, and does very good work.
he did 2 big bore kits on 300ex's for 2 freinds of mine.
he made them 398's.

tell him you know me, he know me veru well.

[Guy400]

I've been reading up on Keihin's website and the Airstryker's seem to have a few upgrades on them. They've got a "D" shaped throttle slide that improves flow versus an oval on the PJ and a round on the PE. The PWK's also employ what they call a "quad vent". Keihin describes it as a vent to reduce bogging when fuel sloshes when landing a jump. The Airstrker's also has something internally that directs more air over the main jet ( I would guess for better fuel atomization).

I had a 38mm Keihin PJ on my '92 LT250R and it was awesome. If the PJ performed that well for me and the PWK has improvements to that design, that's the carb for me! I never knew which Keihin I had on my old Racer but looking at the Keihin site I now know. All I know is that it was a Keihin and had "38MM" on the side. Worked awesome for me.

Basicly the PJ is for low-end and mid. The PWK is for mid-topend. They are almost identical carbs on the outside, it's the internals that are different. Either on would be great, you just have to decide if you want low-mid or mid-top.

[Dave400ex]

My Brother has the 38mm AirStryker Carb on his 250R. He has about all the Engine Mods you can. His Motor is like the one Doug Gust won the Championship on in 99. Doug Gust ran a 38mm AirStryker Carb when he was with Nac`s. Curtis Sparks also runs the AirStryker on all of his 265 Motors too. I think the 38mm AirStryker is better.

[Guy400]

WarriorMan, the 38mm is better for MX or racing set-ups. I'm under the impression that Quad041 is looking for a trail set-up since he had port work done to enhance the low/mid range. For this style of riding the 36mm would be the better choice because of increased throttle response. Go to MacDizzy's site and look at the 250R forum in the message boards section. Someone asked what type of carb they should run for woods riding and the 36mm was the overwhelming response.

[Dave400ex]

Yeah, the 38mm is for MX. My Brother`s Motor is Setup for MX Racing. I thought that`s what he would be riding. That`s all the Pictures are of in his Picture Page. The 36mm would be better for the Woods.

[QuadRacer041]

i am running motocross, but i like to do alot of jumping so im looking for alot of power coming out of turns. most of the tracks i ride on have a lot of doubles coming out of turns and not very long straights, i would think that low/mid power increase would help me in that area.

[400exRacerX]

The airstryker has fins inside the mouth of the carb to direct more air into the main jet.