125-200cc 2012 WR 144 OEM Mikuni vs. Keihin pwk

I just got this bike new with the 144 kit and love it. Other than fuel dripping out when leaning on the stand, the bike is performing great. I have been reading some of the posts and noticed that most have replaced the oem carb.

Is the Keihim carb that much better than the oem Mikuni? And are you getting the carb from Motosportz.com with the JD kit?

Yes the Keihn carb is that much better. Some have got the Mikuni to work great. I swapped out and noticed a huge difference. Worth the money for sure IMO.

The lastest poop on the tiddler carb war seems to indicate that the Mikuni can work well with a needle from a Suzuki RM 125 and modifications from a fellow named Ron Black of RB Designs. The advantage to using the stock Mikuni is that it fits the intake and air boot a bit better than the PWK, which is a couple millimeters longer. However, the PWK works very well, is easy to tune, and pretty inexpensive.

I had a PWK then switched back to stock. There might have been a tad better low end with the Keihin but I like the top a lot better with the Mikuni. These bikes all seem to want different jetting though so you have to see if a Mikuni needle works for you. The advantage of the keihin is that there are lots more needle choices.

Instead of buying a Keihin, if your Mikuni is already working decent, I would send it to RB Designs and get the divider and slow speed mods. After I did that the Mikuni seems better then I could ever get the PWK.

If you do get a keihin I would get the short bodied one like a KTM uses (PWM ??). That way it will fit in the boots better. I hated trying to get the PWK on and off and it make my air boot rub the shock spring.

If you value low end the most get a 36mm.

I do not do a lot of major elevation changes though. The Keihin is supposed to be less fussy so it might be better for this situation. But after the RB mods my carb does not seem to picky as even when it is real rich it still runs decent.

Oh, I found the stock needle to work better then the RM one but like I said, these bikes all want different jetting.

Good luck

Thanks for the info guys.

The oem Mukini seems to be working decent, but I am getting fuel spill when leaning on the stand (alot of fuel), and my freind says also a little dripping riding over rocks and rough stuff. So I guess I have to check the float level and maybe lower it a little.

Would a high float level cuase any low speed sputtering untill I clean it up with some revs?

RB Mikuni

Do you guys who do the Mikuni RB carb mod have him change the slide or leave it stock?

Keihin is better on the 250 for sure....much less finicky on the bottom end...a little less top.

The Mikuni is never right on the bottom end, it does make more top end on the 125 for sure.

cut to a 5.0

I argree fully with Motosports views
I tested just about every carb I could get to fit between the boots, the best combination I found was a 39mm pwk fitted with a divider plate (reed side)
it pulled harder off the bottom than the 36mm and was far better way up on top, I did end up with the KTM 37.cant remember the point lol, but only because it fit in the boots the same as stock (also fitted with divider plate)
Didnt care for the stock mikuni at all ! I could get it spot on one minute then it would all go to pot as the day warmed up or elevation changed.

If you run the RM needle then the 5 is the way to go. I use my 4 with the stock needle.

To the guys running the Mikuni - is that with a CR ignition set up?

Yes.

Nope, I'm running the stock ignition on a 2012 WR144. I have an RB modified Mikuni and just finished running a 2 day qualifier this weekend. Started first kick every time and ran great!

I see there is a TMX and TMXX Mik. Which one comes on a 2012 wr125? My 2012 has TMX stamped on the side, but I read somewhere the newer ones comes with the TMXX.

I think they all should be the TMXX.

Thanks. And will the carb have TMXX stamped on the side? Becuase like I mentioned my 2012 has TMX stamped on the right side of the carb.

My 2010 wr 144 has the tmxx and it has"tmx" on the side and yours will have the tmxx even though it has tmx on it.

Just here to confirm that I am running my 2012 WR with the stock Mikuni with the RB mods......divider plate, cut slide to 5.0, low speed mods, and bored to 39mm.
I have the RM needle in it, the 144 kit, and installed a .4 base gasket. I ride enduro/hare scramble trails at a fun "A" pace and the bike plain "shits and gits"