Two-Stroke Turbo Supermoto! KTM 300 “TworboStroke”

KTM EXC 300 Turbo by Sib Mustard… 

There’s no denying that we’re big fans of two-stroke builds here at BikeBound. Back in 2023, we featured one of the most mind-blowing smokers we’ve seen in some time, the 700cc “MEGASGAS” built by Sebastian “Sib” (@sib_mustard) of HAISL. The young German bike-builder and two-stroke lover took a lightweight GasGas EC300 dirt bike designed for hard enduro, yanked out the stock 293cc engine, and shoehorned in a 699cc liquid-cooled two-stroke Mega engine designed for sidecar motocross!

MEGASGAS: 700cc Two-Stroke Supermoto!

As you might well imagine, the smoking giant made quite the splash here on BikeBound and beyond. At the time, Sib confided in us that he had plans to follow up the giant-bore smoker with a two-stroke turbo build. Today, we’re thrilled to feature that newly completed project, the “TworboStroke” KTM!

The base bike is a 2018 KTM EXC 300 TPI, one of the Austrian company’s two-stroke enduro weapons that weighs in at just 230 pounds dry and makes around 50 hp. Fuel is injected into the transfer ports (TPI = transfer port injection) and transfers to the top of the piston and combustion chamber…though that would soon change.

While turbochargers are rarely seen on two-stroke motorcycles, they aren’t uncommon in the snowmobile world, where forced induction can help compensate for high elevation. Custom turbo snow machine setups first became popular in the 1990s, and in 2020 the Rotax 850 E-TEC Turbo became “the world’s first factory-built 2-stroke turbocharged engine,” making more than 165 horsepower and 100 pound-feet of torque…at altitude!

Sib drew inspiration from the snowmobile world for a turbocharged smoker that would run on two wheels instead of tracks. He converted the KTM from the existing TPI injection to TBI (throttle body injection) to work with his custom turbocharger setup, and you can only imagine the headaches of trying to tune a machine that combines fuel injection, oil injection, and forced induction.

Sib then went on to convert the enduro bike into a top-spec supermoto, outfitting it with 17-inch motard wheels, 320mm disc brakes, custom CNC swingarm, tuned sumo suspension, and enough paint, anodizing, and Cerakote to dizzy the eyes (and pocketbook).

Sib just got the bike finished and has yet to fully test and tune it, but it’s running, riding, and building boost. This “TworboStroke” is the first turbocharged two-stroke bike we’ve featured, and we look forward to hearing more about the riding experience as Sib gets more miles under his belt.

(If you know of any other two-stroke turbo builds, drop us a line (or link) in the comments!)

Here it Wind up!

Builder Interview: KTM 300 Turbo

• What’s the make, model, and year of the donor bike / engine?

It’s a KTM 2018 EXC 300 TPI.

• Why was this bike built?

This is my kind of content on social media. Making extraordinary bike builds. Last year it was the 700cc 2-stroke build (as you know).

What custom work was done to the bike?

The main focus is the turbo on a 2-stroke bike.

• Converted from TPI injection to TBI injection
• It was completely dismantled and recoated, painted and anodized.
• All possible screws were replaced with titanium screws or cerakote coated
• Engine completely cerakote coated
• Supermoto rims
• Tuned and anodized supermoto suspension
• Alcantara seat
• Custom decals in matte chrome
• CNC custom swingarm
• Titan Pipe
• 320mm disc supermoto brake system

• Can you tell us what it’s like to ride this turbo two-stroke?

It feels special because this is very rare and is actually only usually installed on snowmobile 2-stroke turbos.

• Is there anyone you’d like to thank?

My main sponsor HAISL, and the other parts sponsors and my followers, who make financing my projects much easier.

Follow the Builder

Instagram: @sib_mustard
Youtube: @sib_mustard
Main Sponsor: www.haisl-shop.com | @haisl_official