All 2st WHY CHANGE FROM MIKUNI TMX38

FITS: Honda CR 125 (2003-2007) Two Stroke Models
Honda CR 250 (2004-2007) Two Stroke Models
Husqvarna WR 125 (2009) Two Stroke Models
Husqvarna WR 250 (2000-2009) Two Stroke Models
Kawasaki KX 125 (2001-2005) Two Stroke Models
Suzuki RM 125 (2003-2007) Two Stroke Models
Yamaha YZ 125 (2003-2009) Two Stroke Models
They all use the Mikuni TMX 38 Carburetor.

So would my 08 CR 144 improve if I switched to the TMX38 and if so where? Right now my bike runs like a champ and I'm far from good at jetting. Thanks, John

Thanks mate, good feed back? NEGATIVE I'm only seeking feeding back on the off chance that I may benifit from change, I run a 08 WR250 seeking advice?

i do think the same carb on the yz worked alot better there than on the husky, have not tried the pwk but seems everyone loves it on the husky

The TMXX can be made to work well , until you add alot of elevation changes to the mix , then they suffer IMHO

Lets not get our Mikunis confused. It is not easy since two differetn models are called the TMX.

the carb that came on the 125 through 08 and is still on the 250/300 is the one with the rectangular slide. I do not like this one at all. This carb also came on the 01 and up Honda CR250. Swapping this carb for a PWK is also a very common mod for the Honda owners.

The Mikuni on the 09 and newer 125/150 has an oval slide. It is called the TMXX in discussions on this board but I am not sure if that is the real name. Regardless it si the one used on the YZ125 and many others. I am not aware of people with these other bikes switching to a Keihin in large numbers. The main downside to this carb is the lack of needle choices. For myself the RM needle works really well with it.

I bought a PWK when my 09 144 was new and ran it for a while. When I tried the TMXX with the RM needle I thought it worked almost as well but switched to it because it fits a lot better. (the short Keihin from a newer KTM does fit as well as stock BTW). I had RB Designs put a divider plate in and do some low speed mods and it is excellent now. Throttle response is a little faster then the PWK was and it feels like there is more power on top. Bottom pull feels about the same except a bit more responsive. I have not done any large elevation changes but it has worked at least as well as the PWK over temerature changes.

I've never had a problem getting any of the newer (oval slide) Mikuni's dialed-in. The most tweaking I've done on the 3 I've owned has been on my 2011 CR 150. I finally listened to forum 125/150 guru Walt (wallybean) and switched to the RM needle and things have been great.

my TMX38 ('late style' w/oval slide) has been decent to date as well. just fine tuning mostly, no crazy dramas. '09 WR w/OEM 144 kit, RM needle.

krieg, where did you end up jetting wise for the CR150? still getting a lot of spooge at the connection?

what problems are you having ?

I've got a 460 main, 30 pilot, 1.5 turns, RM (17) needle on the 3rd clip. When I went from a 32:1 break-in mix to a 40:1 mix, my spooge went from "belching spooge all over the world" to "just enough spooge to let me know there's sufficient lubrication".

cool, thanks for the update, i'm right in that same ballpark (460M, 32.5P, 1.5TO, RM17-62, 3rd Clip, 5.0 Slide) might go back up on the main, not sure.

Hey MR54L did you think I was being negative?

Hey Johno1, I'm not implying you are being negative. I'm asking why change from a TMX38, not to change over to the TMX38. Sorry for any miss understanding

I have a 08 WR250 with the TMX38-flat slide #3 I did not receive any other slides with the bike and this slide with the below jetting specks, is still slightly too rich. I have been quoted $270 for #4.5 slide for the TMX38. I have even had the float level reset.
New #4.5 slide for the TMX38 or PWK?
Year & Bike Model = 2008 WR 250
Carb = TMX38
Pipe & Silencer = DEP PIPE & FMF TURBINE CORE 2
Other engine mods = 0
Premix ratio & fuel type = 98OCT 50:1 MOTUL 800
Temperature range (deg C) = 18-20
Elevation (meters) = 250
Main jet = JD 390
Pilot jet = JD 30
Needle = JD RED
Clip position = 3RD
Air screw setting = 2 1/4
Slide = 3

$270 for a slide? I paid less than that for a complete PWK airstryker from the US. If you are interested I have the original TMX from my 2010 WR300. I think there is both No5 and 7 slide with that you can have the lot including several spare mains and pilots for $170.00.

No problem MR54L. Your question is a very good one; I too wonder if changing would be better for me. Lots of members on this site have way more knowledge and are willing to try jets, needle, carbs , slides, etc in order to get their bikes running the best it can. I'm sure one of the guys will help answer your question. Good luck.

Is your air screw responsive when you make small adjustments? With a 30 pilot mine was not (all the way out to 2 3/4) so I went to a 35 pilot and the sweet spot was around 1 1/2 turns out. Now it is very responsive to even 1/8th of a turn and a lot more crisp on the low end. I'm using the stock needle so it may be a little different than the JD components that you are using but it seems that 2 1/4 turns out is on the edge of telling you that a pilot change might be an improvement.

Great advice. I read that: If you are less than 1 turn out on the PJ to go down on PJ size and more than 3 turns out go up on PJ size. Is this info correct?

I think that is the general rule but in my case I was within the 3 turns but one size centered the adjustment and made all the difference.

Thanks, good to know.