125-200cc Walt's WR-144 Mikuni TMXX Jetting Revealed!

OK. Since Walt loaned me his carb and left it with me, I've had a few people ask me about the jetting it has. First off, I have a 2012 WR-125 with the 144 kit, 2002 Pro Circuit pipe running on pump premium gas. Walt's carb is a stock Mikuni TMXX with no external or internal modifications except for two small holes drilled into the bowl drain cap to keep fuel around the main jet. We rode at about 4000 feet elevation and I can say I have rarely ridden a bike that ran as crisp as this one. Walt says that the main problem with the stock carb is that the needle is too lean and they try to make up for it with a fat pilot jet. You end up with a rich bottom end and a lean bog in the middle.

Carb: Mikuni TMXX
Slide: 5.0
Needle: 6CHY17-61
Main Jet: 480
Pilot Jet: 22.5
Starting Jet: 80
Float level: 8mm

Yes, I heard that from a few people. However, mine was almost unridable out of the crate. My guess is that someone who knew what they were doing set up the test bike.

A 22.5 pilot? Are you sure about that? That's leaner than anything I've ever seen on a Mikuni. Maybe a 32.5? Does Mikuni even make a 22.5 for the TMXX?

I bet it is 32.5 , I saw 22.5 and was Wtf that is leeeeean

22.5 Pilot.

'09 WR125's with E3 jetting came with 10 pilot jets.

I know Walt runs a lot of high elevations from 6000 - 9000 feet so you may have a good point. The needle was in the middle clip. I was having some trouble starting it so it may have been a bit lean on the bottom for me.

Far be it from me to second guess Walt. I just never imagined a 22.5 pilot.

Well I am finally home this evening from a great adventure to central California, more on that in another thread. First to preface the jetting in the TMXX that I lent to Doug. This is the jetting that worked wonderfully on my 165 from 6000-9000'+. When I gave it to Doug we installed one smaller main to the 480. I am also running a 50:50 mix of 113 and pump premium so the specific gravity of the mix is a bit heavier and needs some richening. I was somewhat concerned about the small pilot but figured that we could quickly change it at the staging area if it was obviously lean. It wasn't obviously lean at all to start and I think the starting issues also coincided with much cooler temps later on. I do believe that it is too lean but still do not think that going up more than one or two sizes will be needed to make it perfect. The reason I have been working away from the richer pilots is to get my bikes to run clean at altitude but still pull hard with the flick of wrist into the needle. I rarely ride with the throttle WFO and love the ability of the 165 to motor most anything on the bottom and pull anything else in the mid-range and reserve the top end for only those times it is really necessary(pulling on the 250F in front of me). Having a leaner pilot and richer needle has worked perfectly for me.

So I don't recommend that lean a pilot for anything other than what I am doing. I do believe these motors respond well to less pilot and more needle. But as has been posted ad nauseum every one of the husky tiddlers is a bit different. When I was running that carb with my 144 I was running a richer pilot, I believe it was a 27.5 and the 17-62 needle also in the middle and a 470 main. This was a high compression top end that ripped with that combination at all altitudes but was still a bit rich on the very bottom(pilot)(didn't like to idle well at 8000'+). I changed it out for the 165 before messing further and I have always used the PWK since then because it works so well on the bottom.

I always hesitate to post in jetting threads because what works for me rarely is what anyone else has in their bike. Most often that is due to altitude, temperature, and other considerations. Crazy thing about this trip was that at much lower elevations my jetting was perfect except for the pilot that was a bit rich. I am running a 38 in my PWK. I don't expect my jetting to work for anyone else but it did make Doug's bike rip. Now when he gets his TMXX back from RB Designs I expect him to have to start over as it will be much more efficient in the first half of the throttle range.

I don't know if any of this makes sense but this is what has worked for me. I have spent a lot of time working with richer pilots and leaner needles with very middling results, especially at altitude. Once again find what works for you and don't be afraid to try new stuff to get there just be always aware of what your plug and throttle responses are telling you.

Glad to hear you and John got back home safely! Thanks for all your help. I have my powervalve governor spring kit here and my RB Designs modified carb arrives tomorrow. I'll have to get up to Montana and ride with you guys real soon. Well... after the snow melts!

After the RB mods I had to drop my pilot two sizes. My bike likes lean jetting also. At about 35 degrees a 30 is perfect. I had a 27.5 for summer and it was always rich.

What elevation are you running at?

Yeah, that sounds about right. That CHY 17-62 needle is 1/2 clip richer than the CHY 16-62. I think my old settings were @ 2nd clip (1 Up from middle on the 16-62), 35 pilot, then sometimes in hot weather 32.5, 460 main @ 900 ft Elevation. If I went too far, I got a little hesitation and that ring ding run on, going from full throttle to first gear. Throw in the higher elevations/richer fuel, quite possible and Walt would know.

Walt, what is your take now on the new WR Ignition vs Cr ignition?

I am thinking, Celtic is gonna have a good running bike with the RB carb mods, spring kit, 150 kit, WR Ignition and Walt doing his magic on the powervalves.

i love these 144 threads

darty, those are very close to my settings as well for summer (~300 - 1000ft ASL: 470M, 32.5P, 17-62 3rd, 5.0 slide, AS 1.5 TO) but i need to go leaner still.

which spring from the kit are you guys using? ive looked at the kit from Hall's but haven't purchased yet to experiment.

I think it is the 17-61 so that makes it 1/2 clip richer. Higher numbers the leaner. Lower the numbers the richer. Gets confusing sometimes then they took off part of the numbers on the online fische. Now you have to call your dealer to get the whole number!!! Argggghhhh!

If you use a 1/2 clip washer shim, you can eliminate the 17 needles completely. Suzuki sells a red one further down the 04 RM125 fische along with a holder that still lets the needle float. When you don't use it, just store the shim on top of the clip so you don't lose it. I use it in the fall and spring when your temps are so erratic, beats changing the pilot underneath.

You can buy 1/2 clip shims for the PWK as well.

Spring kit, that is Walt's @ Hall's your looking at. Think it's $60. He is a mastermind to figure out all those spring rates and etc.....

oops, i didnt realize you were talking 17-61 vs 16-62 in your post, ive edited my comment thanks for clarification!

on the spring kit, got it, but i think these guys are only using one of the springs, correct? thought i read a mention of silver inner only these days (could be wrong on that), was just curious what Celtic is running.

Just to clarify for me.. the 17 needle has the clip grooves machined a 1/2 clip lower, or higher on the needle? Your post first says 1/2 clip richer, then it says higher numbers the leaner? Also, for the second set of numbers, "**-61", i thought the higher the number the leaner the needle? So 61 would be leaner than a 64. Im not sure??

Okay, let me try this without screwing up my mind. The 6CHY16-62 needle is in middle of chart. They go 61 and 60 towards richer (1 Full Clip represent each number). They go 63 and 64 leaner (1 Full Clip represents each number). The smaller the outside diameter, the richer the needle is. Suzuki has an inventory of leftover needles that are CHY 17's, designed for 1/2 clip fine moves (Supposedly, they will be discontinued, once they are gone). The Race teams switched over to a red, 1/2 clip washer shim and holder that eliminates the 17 needles. It was easier to use the washer than to switch out needles. For example: 6CHY17-64 @ 3rd clip position with red washer installed under the clip, is the same setting as the 6CHY16-64 @ 3rd clip.

Here is usually what I do: Stuck my 6CHY16- 62 needle in with a 40 pilot (Middle Clip #3 Position). Runs little rich on bottom, so I raised my clip up 1 full notch and stuck my 1/2 clip washer under it. All I did was do a 1/2 clip leaner move. Now it's better but still little rich. I took my washer out, so my clip move is now a full clip move. Bike runs great, crisp, good throttle response. So, I ordered a 6CHY16 -63 needle, put the clip in the middle and dropped it in. Now it's the same as the 6CHY16-62 needle in #2 clip position. Another way is to reduce your pilot size from the get go.