125-200cc WR 144 carb question

I see my bike comes with a 38mm carb. Which size works best? Keihin 36mm or the 38mm?

My 144 likes the PWK 38 better than it did as a 125. It would seem that a South Jersey sand guy would like the 38 over the 36.

Just got my 144 from Halls the other day. (also have 09 wr125) I myself just do not understand what is the big deal about the keihin carb?? Both of my bikes run GREAT and I never touch the jetting (once setup) Is the Keihin carb just a better thing for c-riders or what?? My 125 rocks and my 144 is awesome. I hope the carb switch is worth the money, but for myself I would not change the carb . To me the stock one simply works great!! good luck.

I've never had any problems either, but from what I've read the tmx
gets very temperamental with altitude changes.

I would still think a 34 or 36mm would work better than a 38mm on a 125. I had my 1982 Husky XC125 carb bored and sleeved down to a 35mm. I still had to run a 530 main jet.
Dwight

I am running a 36mm PWK with no issues. There is more info out there on jetting the 38mm but each bike and rider seems to be a little different anyway. If you ride it in the top of the RPM range then I have heard the 38mm will do a little better. The 36mm still rips on the top end but I have not rode a 38mm PWK equiped bike so I couldn't tell you if the power signs off any earlier.

Do you ride mostly WFO? My son is moving to a WR125 after a few years on a 450 & is a big kid so I expect it'll be at the stops most of the time. He's not picky with jetting, all the 125s he's been on are just pinned. Does the carb make that much of a difference at WFO, high RPM running? Mix of MX & fast woods. Thanks.

If you are riding mid-range to top end with most of your ride time then the TMX is just as effective as the PWK especially with elevation changes of less than 2000'. If you spend much time on the bottom to mid and ride through elevation changes of 4000' or more the PWK handles these conditions much more consistantly. The new TMXX that is on the 09 and newer 125/150 is much better at low end variations but still isn't at the level of the airstriker PWK.

Walt

Thanks Walt, we are sea level only & I doubt he'll ever use anything below 5k besides moving the bike in the pits. Thanks for the clarification.

I agree. Also, what's up with the 144 kits? I have a 125 and it works great, do you guys just like the 144 kits because you're so much slower than me? And is that really why you like the Keihin's so much, because you're a bunch of slow c-riders?

Oh wait...I have a 144 kit and a Keihin, I withdraw the comment.

LOL but you hit the nail on the head for me. I'm a big guy (235 lbs w/gear) and getting older (2nd shoulder surgery) so I put the KX250 out to pasture for a milder and lighter WR125. Anymore I ride off the pipe 50% of the time so having a bit more on the bottom to haul my lard butt around is a bonus.

I am also glad that Fletchman is able to cope with those extreme elevation changes in the mid-west. I rode for a few days between 1000' and 3000' last December before I installed the PWK in March. The bike ran great...oh wait, my rides don't even start below 5000'.

I also spend a lot of time below the power valve opening and sure like the way the 144/167 pull in those areas.

Walt