Tech Info

Welcome to South Bay Moto Performance!

Howdy folks, and welcome to the South Bay Moto Performance web site.  I have been riding and racing off road motorcycles for well over 25 years. I have two sons who have been racing enduros and hare scrambles since they were 5 and 7 years old. They are both grown young men now still riding and competing.  I have spent countless hours researching and testing, always looking for ways to improve the motorcycles. In this article, I’d like to share my experience with the Two Stroke Performance power kit upgrade for the KTM and Husky, fuel injected two stroke motorcycles.


In late 2017, when I first heard about KTM launching their TPI line (Transfer Port Injection), I was really excited to know that KTM was finally launching a fuel injected two stroke motorcycle.  Not having to spend time properly jetting a bike, as well as cleaning jets, seemed like a positive.  Having the bike auto adjust the fuel mixture for different elevation gains also seemed enticing.  Not having to mix oil in the fuel and having the bike auto inject the two-stroke oil based on throttle position and engine RPM seemed brilliant. I quickly called my local KTM dealer, The Motor Café, and put my order in asking to get the first 2018 KTM TPI that shows up.

When my new 2018 KTM 250 XC-W TPI arrived, I was eager to do the usual new bike prep, and get her out on the trails and experience the TPI.  Well, let’s just say, I was a little underwhelmed.  The bike started cold on a dime.  It idled great, and I was blown away how clean it ran.  No smoke and zero spooge or carbon build up on the muffler.  However, right away I noticed how soft the bike felt off idle, no punch at all.  It was very smooth and tractable but very little hit off the bottom.  This had me concerned, because I like to ride very technical trails with lots of obstacles, and I have always liked my bikes having a strong power delivery down low.  The mid-range seemed OK but not great, and overall the bike felt lean.  I played with different power valve settings, added a true idle screw, and adjusted the air screw.  I even tried a few different maps from the dealer, but overall, the bike was just OK.  It was not quite what I was expecting, and nowhere near what my previous Carb bikes felt like.  I was left with a feeling of wanting more.

In late 2018, I purchased a 2019 KTM 300 XCW TPI for my son who would race the local enduro series on the bike.  This bike had noticeably better low end and mid-range than the 250 TPI, but it too had some odd quirks that were a bit annoying from a brand-new, performance oriented, two stroke motorcycle. The KTM 300 TPI seemed to have a bog or stutter at certain throttle positions, and it seemed to sign off too soon up top.  UGH!  Feeling frustrated, and not being able to “tune” the bikes to our liking, I started researching options for aftermarket heads and ECUs.  We tried multiple product combinations and were able to find more power for both the 250 TPI and 300 TPI.  However, the increased power also came with some drawbacks, like unpredictable power surges, pinging, or pre-ignition at over-rev, and cold starting issues. Still not happy, my son asked me to pull everything off his KTM 300 XCW TPI, as he preferred how the bike ran stock vs. the aftermarket ECU and head we just spent $1,200 adding to his bike.

Then one day, I found Two Stroke Performance out of Australia.  The owner, Dave McCarthy, has been successfully building and tuning two stroke motorcycle engines for a very long time.  He advertised a TPI solution that reflashes the OEM ECU with improved fuel and ignition mapping and pairs it with his own custom design CNC head that can be ordered in different compression ratios to suit any rider’s preference. I spent many hours researching and reading reviews on the Two Stroke Performance Power Kits that Dave was offering for the KTM and Husky 2 stroke TPI’s.  Dave and I spoke on the phone several times, as I barraged him with tons of questions and sharing my experience and dissatisfaction with other aftermarket products I have tried.  I was not about to throw away anymore money chasing a tune that may not exist.  I was pleasantly surprised by Dave’s demeanor and low-key attitude.  In speaking with Dave, it was obvious he is an expert in his field, has done his homework, and knows what he is talking about when it comes to modifying these TPI motorcycles.

I decided to purchase the Power Kit for the 2018 KTM 250 XC-W TPI and see how it performs.  The kit came with an ECU reflash of my stock OEM ECU, a high compression head, a new spark plug with a different heat range, and an idle screw.  After installing the kit and taking the bike on a ride, all I could say was “WOW”.  Holy Smokes!  This was a completely different bike.  The bottom and mid-range power increase was significant.  Most noticeable was how smooth the power delivery was from bottom to top:  no hiccups and very predictable.  The bike even seemed to run a little cooler, probably from the richer fuel mixture. This new TSP set up exceeded my expectation, and I was ready to invest in the TSP Power Kit for the 2019 KTM 300 XC-W TPI.

Installing the TSP Power Kit on the 300 was going to be the true test, as my son is a huge critic on how he likes his bikes to run. He is a AA rider and has been racing since he was 5 years old.  We did the TSP ECU reflash with the medium compression head for his 300. The results were amazing.  Bike ran way better than stock, and my son was happy.  He ended up winning the AMA District 36 Enduro Overall Championship in 2019 on this bike.  He’s happy.  I’m happy.

Idaho trip and the 2020 KTM 250 XC TPI with TSP Power Kit

In late 2019, I heard KTM was going to be offering the TPI models in the XC line up, so we put our name on the list and picked it up at our local dealer, The Motor Café, the day it arrived.  The 2020 KTM 250 XC TPI ran much better stock than our previous TPI bikes, and I wasn’t even sure it needed any modifications. After speaking with Dave at Two Stroke Performance, about the new 2020 250 XC TPI, he agreed they were good right out of the box, but his new custom maps and heads would make it even better. So we gave it a try, and he was right.  Wow, the bike really has a strong bottom end, pulls smooth through all power transitions, and pulls very well up top. That’s three TPI bikes that we have owned, and all three are fitted with the TSP power kits. They are amazing running bikes.

Every year we plan a trip to Idaho.  This year we went to Gold Creek Lodge with a large group of riders from NorCal.  After one of the rides where the “fast guys” went off to hit some monster hill climb, my son came back with the biggest smile on his face saying, “you should have gotten that on video”  He was on the 2020 KTM 250 XC TPI with the TSP power kit, and he said he dragged raced a well running KTM 350 up a monster hill climb.  The 350 got a head start and he said he pulled and passed the 350 half way up the hill and couldn’t believe how strong the motor was on the 250 with the TSP set up.  His smile said it all.

When my boys are happy, I am happy, and it’s always nice to invest in products that exceed expectations and make the riding experience that much better. I am 100% sold on the TSP set up.

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