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2/16/2025
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MIDDLEBURG, PA, USA
posted this in another sub and just looking for more feedback.
has anyone else gotten their hands on one of these carbs from Stic? you see a lot of great things about the keihin pwk w stic metering but only a handful of people that have been able to use the stic carb itself, and those people say its even better than the pwk paired with stic. seriously considering one of the two to replace the mikuni on my 19’ 150sx.
What’s different on this vs a lectron or smart carb?
Everything.
The Keihn is a traditional carb with Jets. The “STIC” is a mod.
Something I’ve been meaning to buy but haven’t jumped on. To be completely honest my 38mm keihin with STIC on a 300sx is way too much fuckin power and response for my level. Every time I think about switching to the complete setup i talk myself out of it.
We're interested in the Super X carb also. While I'm here I have to say we are very happy with the STIC metering blocks in our 150sx and YZ250, currently in five bikes. More bottom and screams on top and runs cooler due to the way the stic spins the air in the emulsion tube. It's quite amazing, I wish all two stroke guys would pick one up. Be sure to get a 'thin tip' needle (JD does a proper stic needle).
The Shop
Free shipping: VITALMX
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
Luxon 4-Post Bar Mounts
$189.95 - $239.95
what size is the thin tip needle?
Thin tip needles are the NECx, NEDx, STIC red/blue/white, N3Wx etc. Can also use Yamaha N3Ex needles with the tip ground down.
I need to play with the STIC needles again but they seemed soft to me vs the Suzuki and Kawasaki needles.
For the 150sx 114a tube or the 113?
Metering rod carburetors suck for motocross. Theyre always lean, and give the rider the illusion of proper jetting. Maaaybe in the woods theyre "decent"? (Prob not) Did the metering rod salesman sell you on using less fuel? Hint: (always lean)
The best 2 set ups (pick your poison)
I dont expect anyone to follow this.
We were recommended 113A for 125/150 and 114A for 250. Definitely seems to work.
TMX jet block seal is poorly designed. Elastomer seals must be encapsulated to prevent extrusion, the Mikuni one isn't. JD has an improved seal that has a vulcanized metal core, but it's a bandaid. No amount of jetting will fix this carb until the seal is resolved. Once resolved, it's nowhere near the performance of the STIC. The 4 billion page Jarvis thread on TT wouldn't exist if the TMX were a great carb.
For anyone choosing to use this carb, be sure the slide stop is in far enough or the slide will crumble apart letting metal chunks travel through your engine.
Mikuni is easy to dial in. In the KTMs its replace the jet block gasket with the JD gasket , slide and thats it . The rest is playing with jets and float height like any other carb. I have a KTM with TMX38 that has that problem and now is running excellent , spending 100$ in carb parts. A lot of people just spend 550/600$ in a keihin ( wich is a excellent carb) when the mikuni is easy to fix, i only change main and pilot in extreme cold or hot weather. 50-80°F range i use the same jets only play with the air screw. After saying all this, im really curious and id love to try a keihin with theSTIC mod but its like 800$ in tokyo off road , i prefer spend a little less in tsp, apex head and keep that mikuni that works great
I've both looked at the dyno charts, and ridden them back to back. Mikuni after the repairs is slightly better on top. Exacerbating that is it's pretty hard to get a Keihin to not go a bit flat at 3/4 throttle. However, a Keihin is way better down low even compared to the Mikuni with S8. On a 250, the Keihin is leaps and bounds better due to the improvement on the bottom end. An argument for the Mikuni for a 125 is valid. Throw all this out the window for a STIC kit in a Keihin.
Other than the basic R304 silencer and Tassinari reeds, most changes to a 2T aren't additive. You are compromising one benefit for another. Porting shifts the optimum RPM range. The Keihin STIC kit increases power across the entire RPM range. The only penalty is fuel consumption. A Mikuni, or a Keihin, no matter how well tuned, will not compete with a STIC equipped Keihin. The difference is so profound you should anti-MXA the bike and drop a tooth on the rear. It's the real deal, no other bolt on comes close. I have no affiliation with STIC, in fact I find them hard to work with, but their technology is amazing and completely worth it.
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