THROTTLE BODY INJECTION
Dear Mr. Know-It-All,
Q: I just picked up a 2024 KTM 300XC-W TBI, and while it’s smooth and predictable, it just feels like it’s missing something compared to my carbureted 300. It doesn’t quite have the same response or grunt. What’s the best way to get that feeling back?
MR. 2-Stroke Die Hard
Premixville
A: Dear MR. 2-Stroke Die Hard, We hear this a lot from guys coming off older carbureted bikes. The new TBI is smoother, more linear and takes away some of that raw, hard-hitting feel that carb bikes have. Some riders love it because it makes the bike easier to control in technical terrain, but if you’re used to that two-stroke pep and playfulness, it can feel like something’s missing.
We’ve been testing products from around the world to bring back that classic two-stroke grunt and response while keeping the benefits of TBI. We have tested a lot of setups, and the winning combination we’ve found is the ERM oversized power-valve cover and high-compression head by Two Stroke Performance out of Australia. Each of these helps the bike feel more alive and connected to the throttle without making it unpredictable.
TSP ERM KIT: CLEANER, STRONGER RESPONSE
The first thing we’d recommend is the TSP ERM. This is an ECU re-flash module that fine-tunes ignition timing and fueling, helping the bike respond more like a well-tuned carb model. From the factory, the TBI mapping is on the richer side, which smooths out the power but can also make the bike feel a little sluggish. The ERM tightens up the throttle response and gives it a crisper, more reactive feel without making it too aggressive. It also allows you to read and clear codes that may pop up.
With TBI, the system meters fuel more precisely, which makes the transition smoother but less punchy. The ERM helps bridge that gap by sharpening how the bike delivers fuel and ignition timing. You’ll notice that rolling on the throttle feels more immediate and that the bike pulls harder through the midrange without feeling like you’re waiting on it to pick up before coming into power.
TSP OVERSIZED POWER-VALVE COVER: MORE POWER WHERE YOU NEED IT MOST
Next up is the TSP oversized power-valve cover. This one often gets overlooked as a “bling” part, but it makes a surprising difference at low throttle and low/mid revs where most riders need it most.
Two-strokes rely on pressure waves in the pipe to boost power at high rpm, but those same waves hurt low-end performance by disrupting flow into the cylinder. The TSP oversized power-valve cover increases the chamber’s volume, further reducing these negative effects and boosting power between 3000–5000 rpm. This gives the bike stronger low-end response without sacrificing top-end performance.
HIGH-COMPRESSION HEAD: MORE GRUNT OFF THE BOTTOM
Finally, if you really want more low-end torque and grunt, a high-compression head is the way to go, especially if you are riding at elevation like we are in Colorado.
A high-compression head does two things:
1. Increases torque and throttle response. With higher compression, the engine burns fuel more efficiently, so it produces more power earlier in the rpm range. This helps bring back that hit and grunt that carb bikes have when you crack the throttle.
2. Makes the bike feel more planted. Higher compression increases low-end power, meaning you don’t have to rev the bike as much to get traction. This is especially noticeable in technical terrain where you want smooth but strong power off the bottom.
This mod makes the biggest difference in tight, slower sections where you’re working the clutch a lot. It also pairs perfectly with the ERM kit and power-valve cover because it fills in the low-end grunt that the other two mods don’t touch as much.
HOW DOES IT RIDE AFTER THESE CHANGES?
Once you install these three mods, the bike immediately feels more responsive. The ERM cleans up the throttle response and flat spots, which makes the power more direct. The oversized power-valve cover gives you maximum torque at low revs before the power valve opens up, and the high-compression head provides that low-end grunt that you are missing.
You’ll feel the bike pull harder out of corners, rev quicker and respond more naturally when you get on the gas. The best part is that it doesn’t turn the bike into a wild, hard-to-control monster; it just brings back that raw, connected feel that’s missing from the stock setup.
If you’re looking for a way to get your 300 TBI feeling more like a well-tuned carb bike, this is the setup I’d recommend. It keeps the smoothness and efficiency of TBI while making the power delivery sharper, stronger and more fun to ride.
The post MY 300 TWO-STROKE FEELS SLOW, HELP! – MR. KNOW-IT-ALL appeared first on Dirt Bike Magazine.
