Fixing the Mikuni TMX Carburetor

[@herdfreak2]

I have watched this video 5 times now and ordered everything from JD Jetting for my 2001 Suzuki RM 125.

[@highlandcycles]

James Boreman awesome. I think you’ll be really happy. Just remember that every bike is a little different and you might have to make minor adjustments.

[@herdfreak2]

@@highlandcycles 761’ Elevation 93 Octane 32:1 oil mix ratio 430 main jet 27.5 pilot jet 1.5 turns out on air screw I’m learning a lot from your videos! 👍🏻

[@highlandcycles]

@@herdfreak2 Great to hear

[@herdfreak2]

@@highlandcycles The more I know, the more I enjoy riding my DIRTBIKE!!!!

[@rsendurouk3647]

2017 KTM 300 mikuni tmx38. Starting jet 80 Needle jet r8 Idle jet 37.5 Main jet 440 Jet needle 43-73 #2 Great crisp sound no booge. Great bottom end and crisp sound!!! Do not need to spend £90 to get most out of it...

[@highlandcycles]

RS ENDURO ABERDEEN thanks! Great info.

[@natestraeter5326]

What elevation are you at?

[@rsendurouk3647]

@@natestraeter5326 i could not be bother with constant adjustment every time weather changes... Bought lectron mule h series from Slavens racing US!

[@natestraeter5326]

@@rsendurouk3647 I gotcha. I’m actually going back to the mikuni after having the lectron for about a year. Not having to jet was nice but it had an incredibly hard throttle pull. Bought the supposed lite slide spring from slavens and felt exactly like factory. Trimmed down/polished the spring with only marginal benefits

[@mikebalzer9671]

Thanks for your specs on the Jetting but what fuel Ratio do you run and at what elevation? Just bought the jet needle and going to try it in my 2017 husky 300TE. My float was set way high from factory and would leak out of overflow. That was my first fix.

[@woodworm3615]

No O-Rings under the 2 screws in the Jet-Block-Seal area. Just the updated Gasket from David at JDJetting. On the Float Jet. Yes there is a crapOlla O-Ring here. Change out just as you have done. Alles Klar mein Ami Mechaniker. Servus!

[@highlandcycles]

Wood Worm thanks, I actually figured that out a while ago, just haven't made a new video. I will update soon.

[@SANDS78]

Yeah no O Rings here either on the 2019 150. I don't understand why or how it would need those on either side of those screws. Wouldn't that defeat the purpose of the jet block gasket? Those o rings sit higher than the gasket.

[@glenngertz9429]

My brand new 0 hours, 2019 Yamaha YZ125 with Mikuni TMX 38 has this problem as well. This problem is not exclusive to just KTM and Husky . Also the needle seat was wobbly in the carb body and leaking fuel, overflowing because of a shrunken seat Oring. 0 zero hours on this bike, crazy. These must be new old stock carbs like you mentioned. Thanks for the video

[@highlandcycles]

Glenn Gertz thanks for watching.

[@arloslab3469]

I think I should buy one of these kits, My 2015 yz125 (has Mikuni tmx38) Has bogging issues, It rides normal but when I slam the throttle all the way down in high gear while in low rpm it bogs, maybe the needle ?

[@highlandcycles]

Definitely could be.

[@arloslab3469]

@@highlandcycles ok

[@DavidMartinez-uz2vf]

I have a 1996 YZ 125 with a TMX 36. Will a TMX 38 work cause im having trouble finding 36 parts needle n seat

[@scottlichlyter1533]

Were is your shop located at great show buddy

[@highlandcycles]

Montrose CO

[@Daniel456324]

What do you call this main jet screw in brass fitting? Where do you get the replacement o-ring at?

[@highlandcycles]

Needle jet and most kits come with it.

[@FourthWayRanch]

I can't find a tuning manual for the TMX38 carbs. There is info in the catalog about them but no float height data?? did they make a tuning manual like they did for VM carbs?

[@highlandcycles]

Not that I know of.

[@highlandcycles]

@@FourthWayRanch I set them at 8-9mm. Seems to work well.

[@Aaron-fx5zi]

I’ve ordered the jd jet kit for my 2020 250sx along with the oring gasket. Is there any thing else that can be modified ie the slide, float bowl or overflow tube?

[@highlandcycles]

Some people have cut a notch in the slide but I don’t think it’s worth it. You need to set the float height for sure. And I like to loop the overflow tube over one of the vent lines too.

[@FourthWayRanch]

I just bought a couple of these, I wonder if they've fixed the bad seals issues yet?

[@highlandcycles]

Gotta check

[@highlandcycles]

@@FourthWayRanch it’s easy to check. I’d do it if they were mine.

[@FourthWayRanch]

@@highlandcycles they've been totally re designed, u can see in the catalog. only one o ring on a plastic insert now

[@highlandcycles]

@@FourthWayRanch that’s rad

[@farmer3242]

Do you do the filing mod to the 2019 mikuni slide? And drill the holes in the drain bung?

[@highlandcycles]

No

[@farmer3242]

Why dont you do that mod?

[@highlandcycles]

@@farmer3242 don’t need to.

[@lucianobragho3088]

hey man i have a husqvarna tc 125 2018 and is very rich at medium revs, i’ve tried to recarb it but nothing, this kit is it also good for my bike?

[@highlandcycles]

Yes

[@landonbutler4097]

I accidentally stripped the screws to the jet block. Do you by any chance know what kind of screws these are

[@highlandcycles]

Dang. I don’t.

[@jaybird99100]

Ever have any problems with the bike stalling during long downhills or during pivot turns? I have the mikuni carb in my 17 300 XCW. Put in the JD kit with jet block gasket and needle seat O-ring. Bike runs much much better than it did from stock, but have this stalling issue now. If the clutch is pulled in and it's sitting in first gear and I just lean the bike over to the right it will quit. My rpm is set properly, clutch is good, I'm leaning towards float bowl, but i've double checked that a few times now. Any thoughts?

[@highlandcycles]

Jason Keddy yeah man. That is common with the carb if you haven’t set the float level right. From the factory they seem to have the float to High which effectively make it too rich and over flow when ripped. Set that height at about 9mm and you should be good.

[@jaybird99100]

@@highlandcycles Awesome, thanks so much for the reply. I see the spec is 8.7mm +/- 1mm i've tinkered with it, but with very little success. I'm going to go back to the drawing board with it tomorrow and see if resetting it more accurately will solve the problem. My lectron didn't do it, so that's why I figured it must be a carb issue. i just prefer how the carb delivers the power so would like to stick with it if i can get the stalling issue out of the way. Thanks again. I'll let you know how I make out.

[@highlandcycles]

Jason Keddy right on. Also make sure you do the loop thing with the hose

[@jaybird99100]

@@highlandcycles yeah no dice. I set the float to 8.5mm (couldn't get that last little bend enough for the 9mm you recommend), but figured it was close enough. Bike still stalls when leaned over, but funny enough it only stalls when leaned to the right and not the left I noticed. Floats are equal in height. Would the angle the carb is situated in the intake boot make a difference. I've got it in the notch where it goes, but there is some movement to be had there. 10 degrees or so. Really scratching my head on this one. Runny 30 pilot, blue needle clip 3, 420 main with jet block fix and needle seat O-ring fix.

[@highlandcycles]

Jason Keddy that is odd. Doubt it has to do with the carb angle. Could be that the overflow tube is on one side and not the other.

[@keesgroeneveld965]

Nice video! could you advise what dimms yr o-rings are? does mikuni have that standard in? I have the mikuni TMX38/kawa kx125-05 and she is leaking gas. thanks

[@highlandcycles]

Unfortunately I don't know the size and I am not at the shop right now. But If you call JD Jetting they can probably tell you. The ones that come in their kit are a little bit fatter than the stock one.

[@purasenatus8783]

Having a issue with my 2016 yz 125 bike has a high idle. Air flow is nearly closed if I open it the bike sound like it’s about to blow. Search for leaks none visble with the naked eye. Can anyone help ?? Or know that having any of these known problems from this videos would cause the same issue I’m having.

[@highlandcycles]

Check your left main seal. Behind the stator.

[@stevemarquez9628]

Do you run pump gas? Looks like they are jacked by ethanol.

[@highlandcycles]

I run ethanol free pump gas

[@enmerdeur]

Here is my theory: What bike used to use this carb? The old Husky WR250/300. After KTM acquired Husqvarna some KTM employee stumbled upon a warehouse from the acquisition with a bunch of Mikuni TMX's stored in there (think end of Indiana Jones for a visual). Who knows how long those things have been sitting in there. Said employee sees $$$$ and goes to the marketing department and says, make something up that makes it sound like switching to the Mikuni is a good idea and voila!

[@highlandcycles]

Reno 1960 hahaha. Love it

[@eve1dance2experiment]

You mentioned the needle problem. What needle should I use? Thank you!

[@highlandcycles]

eve pollard I like the JD Red Needle.

[@eve1dance2experiment]

@@highlandcycles I'm Brian on Eve's account. If you use the JD red needle, do you use their jets? If so, which ones. I live in Richmond, Va. Altitude about 170 feet.Thanks for your replies.

[@highlandcycles]

eve pollard I do use their jets. I actually run one leaner on the main than what they call for. We are at 6000 ft

[@billybobbubbawubba9457]

At least they have a replaceable seat for the fuel needle. Keihin sucks for that.

[@highlandcycles]

Agree. I have never understood why Kehin doesn’t do that

[@johnhardiman871]

My bike never had the 2 small orings on the Jet Block? I got the JD kit....did come with 2 orings ... used 1 for the Needle / Seat deal. Bike runs great,,,,

[@highlandcycles]

John Hardiman those o rings are for beside the gasket because the new gasket is so much thicker than the old one. As long as yours is running well then I say run it!!

[@herdfreak2]

I made the change using the kit from JD Jetting, ready to ride here in Charlotte(NC). We’re at 761’ above sea level, using the Pro Circuit Racing jetting specs. I race in the nchsa.org/ here in NC, ride a 2001 Suzuki RM 125 and a 2018 Suzuki RMZ 250. Jim Boreman #304

[@highlandcycles]

Sweet!! Go fast!!!!

[@teemill450]

👍 this vid people!

[@tylerb137]

After seeing this video i checked my 2019 300xc with only 15 hours on it and the oring jet block oring is blown out

[@highlandcycles]

Tyler Burns it’s crazy