https://sbmotoperformance.com/product/tsp-power-kit-plus-ktm-husky-125c…
https://www.twostrokeperformance.com.au/
Picked up a low hour 22 KTM 125sx to build into a race bike for my son. He's a pretty solid C class rider, running local PNW races in the 125 and 250 Jr classes. Qualified for Mammoth this year so has some speed.
The 20 we've been running is mostly stock. Has an RK Tek head insert, VForce 4R reeds, and an FMF pipe w/Shorty. It's always run well with the Mikuni jetted per MJ's thread here. Nothing fancy and we get a solid 25 hours out of a piston thanks to quality work by Jim Haeseker.
I decided to give this kit a shot on the new bike. High compression insert with billet head (we cracked the head on the 20), custom ECU, and a Keihin carb. This bike has Vforce 4R reeds and the same exhaust as the 20. Right out of the box freshly installed it ran just fine. Did a touch of airscrew and Powervalve tuning and that was it.
We now have 5 hours and 12 gate drops on this build. 3 hole shots, 6 top 5 starts, with the other 3 starts bad launches (rider error). This is going up against other fast 125s or 250/450s in Open classes. This weekend he gated with the 250 Pro and Int class and was wheel-to-wheel with AMA Pro #480 Ashton Oudman, a very quick PNW kid, all the way into the first turn. So the motor makes really good power. Running T2, the plug is spotless and we're not seeing any detonation.
Over the winter I'll have Jim Haeseker do his stuff with this kit and the Powerparts factory cylinder we have, shooting for 15 hour piston life. I expect his work to really wake it up and push it past 40 HP.
Good products, rapidly delivered, easy to install, makes a noticeable difference. When we get the 20 all back together we'll do some back to back tests to see how they compare.
That's a lot of scratch, good thing it works well.
If you had a 4 stroke and bought a new vortex with map it's not far off that cost.
Tuning any smoker is usually jetting or carb and head work, having option to add ignition is cool... fuel, spark and head are the keys to power and if it's dialed in on a dyno then awesome.
Lots of reeds and pipes etc often make no difference or make it worse.
I agree on the pipe and reeds being a waste most of the time. That kit is spendy all the same, but clearly works well. I am a fan of CDI tuning especially. Be real curious on the Hard Parts cylinder from the OP.
Spendy is all relative right? We will be keeping this bike for at least 100 hours so I'm fine spending the coin up front to make it better.
I haven't tested pipes/reeds to any extent other than stock vs the FMF/VForce we usually run. Differences are subtle IMHO but I don't ride the bike. Sponsored by both so we run them.
Re the hard parts jug, bought that with some KTM contingency $$$ thru our local dealer (also a sponsor) so got a pretty good deal on it. Still had to buy all the power valve parts to make it a complete assembly. We put it on the 20 w/o any other changes, and my boy said it was noticeably better throughout the rev range. I could see it too - he was lifting the front with ease under hard throttle even at lower RPMs. The TSP kit seems to be a mid-top kit (hey, it's a 125 right?) so I think when we move the hard parts jug to the 22 it will help even more. Then I'll have Haeseker go over the motor this winter with some mild porting. He says the max he shoots for is about 42.5 HP on these to maintain reasonable reliability. I'll be happy with anything over 40 and 15 hour piston life.
For suspension we run MX Tech Luckys up front and their Tank on the shock, all set up by JB Covington at Ride JBI. The bike is very competitive as it sits, and I expect good reliability. The 20 has been solid, now at 130 hours. I did the crank at 100, and replaced 3rd and 4th gears then too. We did have the stock head water jacket crack near the spark plug hole at 110 hours. $39 part.
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Oh yes, totally relative! Kit sounds great and certainly works, cool thing that it is a bolt on. Looking forward to hearing more.
I've been running the new STIC
Super X2 carb, US cast Keihin clone modified body with unique internal metering block circuits. Makes smaller bores savage right off idle thru an extended stronger top end. Comparing jetting specs to a std Keihin, 45/178 vs 80/200! The pilot actually reverses flow and feeds right above the main jet. It sources air/fuel vapor accumulation at the intake bell via an air jet. Air speed injects hi pressured vapor into the jet tube, which has low pressure at the jet tube top, just below the outlet orifice.
The jet tube is perforated, receiving vapor from the venturi. This accelerates/lifts fuel from the float bowl. As the fuel level drops, the perforations lean the mixture. Thus resulting an increase in power.
The performance increase for a stock engine is astounding. To make mine manageable I installed a slow turn G2 #400 throttle cam.
The July introductory price was $564 US. Not sure about current pricing. FYI, Steinke ran the STIC block in a Keihin and Jared Lesher YZ250 in 450 SX and Nationals.
US cast Keihin clone? Is this specifically for the STIC? I have run several variations of the STIC myself on 125/250&500. I was most impressed on the small bore. Definitely curious on the newest incantation.
Yeah I coulda got this kit w/o the keihen. Happy to test for someone.
The small bores actually get strong low end power right! On technical trails it's like an electric motor. Almost no clutching. Just lug it and twist the grip.
Everybody gets the power down like a pro and shifts can be made in a much wider rpm range. No bad shifts. Always in the 'meat' of the power.
And yes, there are changes to the body, as to implement the full STIC system, i.e. hi-pressure vapor introduced at the bottom of the jet tube.
Well, the ppl that swapped to Keihin. They are happy they did, bc they don't need to fuss with jetting nearly as much. Besides better power below peak HP.
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