Mikuni 38mm TMX vs Keihin 38mm PWK Airstryker

[xcxtr3e]

I'm just trying to do a little research, and am hoping there may be tangible reasons for choosing one carb vs the other. Hope it doesn't turn into a debate, a la "what 2-stroke oil" do you use! :lol:

85 250R - My plan is to have porting done to my stock cylinder/head, and I am pretty sure I have my exhaust upgrades covered, just looking at the best options on intake side.

Woods/MX or low/mid range power is what I hope to achieve with port job, for exhaust I'll be running an FMF fatty pipe (got a good deal on a new one) and ESR silencer with spark arrestor. I am open to upgrading pipe down the road, for now I'm sticking with the FMF.

From what I've researched so far, both of these carbs have good reputations but I could not find a thread on an actual head-to-head comparison of the two. The Mikuni is about $50+ cheaper on Ebay (NEW), so if these two carbs are virtually even performance/reliability wise then that could be the deciding factor.

Also, wondering if either carb (perhaps both) require modifying for proper fitment.

Thank you kindly, -Chris

[Mosh]

Without question get the PWK 38. The mikuni will be a P.i.t.a to jet. You will have to heat up both intake and reed boots to get the carb to go in. IMO I would buy a new UPP intake for the 38 mil carb.
You will also need a Special application Motion pro cable to fit the PWK 38 correctly. Motion Pro cable part number is 06-1604. That number will fit your stock thumb throttle and PWK carb.

[3wheelrider]

Im no expert -but ive tried both on 250Rs and cannot stand the Mikuni. Its a PITA (IMO) + fuel inlet & idle on opposite side -I cant stand that alone. The jets for the Keihin are more common/available also.The Mikuni might even perform better-I dont know & dont care. They both fit and work great but for me its Keihin PWK-no brainer.
Mosh U beat me by a few seconds....lol

[xcxtr3e]

Thanks you guys! I also appreciate the reminder on the throttle cable, with part #

[christph]

I investigated this too--Mikuni vs. Keihin--and discovered the overwhelming opinion agrees with what has been said above. Something not said, however, is that the Mikunis are also very temperature sensitive. The Keihins run better over a wider temperature range before you have to rejet them. Just another reason to go with the Keihin.

[pcs]

For the shade tree mechanic, pwk. For dyno tuning the mikuni is better and if u decide that you need more carb in the future for more hp or bc u add a b.b. Kit the mikuni can be bored out up to 41.5mm

[xcxtr3e]

Thank you for all the great advice. I think I'm going with the PWK Air Striker - and for anyone else shopping/researching, you may find this helpful - There is a small difference between the PWK and the PWK Airstriker.

I'm guessing many of you are aware, however I thought I'd share. I've attached a photo highlighting the "air strikers" accompanied by a brief explanation borrowed from dirtbikeworld.net, here's the link to the original thread http://www.dirtbikeworld.net/forum/showthread.php?t=22003

1. not a huge difference really as far as perfrmance goes ,some say the airstrykers are harder to jet on drag bikes ....the air stryker has giuded fins directed and aimed at the needle jet which improves lowend response ,also theres quadvents whcih are just basiclly a couple more specialized vent lines ,this is done for mx/freestyle applications when you are jumping and such so theres no trouble with airlock from fuel sloshing around in the bowl

175472

[jb104]

I installed a mikuni tmx 38 on my tecate about two weeks ago with a new motion pro twist. It fit perfect on the stock intake and started on the first kick. I only rode a little bit at the dunes last week but to me it seemed good out of the box. I had a pwk 39 on my other tecate and it also worked well. I do know that the tmx will fit on the stock honda intake but the pwk I don't think it will. Good luck let us know how she runs after you slap the new carb on.

[xcxtr3e]

Also wanted to thank yamaha225dr & RIDE-RED 250r for the valuable information contained in the thread "Holy horsepower!" - I wish I had seen that thread earlier, it probably never came back in any of my search results because the of the title, but I discovered it just browsing back through previous threads. I too hope I can share good news once I have everything.

[RIDE-RED 250r]

For the shade tree mechanic, pwk. For dyno tuning the mikuni is better and if u decide that you need more carb in the future for more hp or bc u add a b.b. Kit the mikuni can be bored out up to 41.5mm

Just a friendly FYI, the PWK can be bored to 40.5 as well....

[pcs]

The center of the carb body on the mikuni where the needle slides in is brass and can be removed when u bore it out, on the pwk that portion is casted to the body so u cant truely bore the pwk but u can still taper bore it

[TecateDan]

I had both at one point and I threw all of my mik stuff in the trash. After a year of messing with Jet's boled on a PWK and BOOM problem solved. Don't care if it's faster I'll never run mik products again

[Jason Hall]

The tube can be removed on a PWK from under the bowl with 2 tamper proof torx screws. I have bored PWK's to 41mm..

[yamaha225dr]

I have never had problems with Mikuni carburetors that came stock but I would never buy a Mikuni over a Kehin when it comes to upgrading.

[stroberts22]

I got a tecate with a 38 mikuni carb on it. It runs very well with it but it's allot of trouble just to raise and lower the needle so I see where it would be hard to tune to get right. The keihin takes no time to change the needle height. Why did all the old racers use the mikuni? Must be something there.