KTM 250 SX Platform

Big bore two-strokes aren't about lacking power; they're about managing it. For the 250SX rider, we focus on broadening the hit to create a '450-killer' weapon. For the 300 XC/Enduro rider, our focus shifts to 'Linear Torque.' We reshape the power valve and transfer ports to eliminate the violent 'hit,' turning your 2-stroke into a traction-finding tractor that creates grip where others spin.

📉 Dyno Verified Performance

The Stock Bottleneck

"Factory limitations holding you back."

The HP Race Dev Solution

"Engineered performance."

We don't just "grind ports." We mathematically correct the engine's geometry to solve this specific flaw.

Select Your Level

Choose the package that fits your racing class.

KTM 250 SX Platform

250cc Platform

Minimum Spec

Reliability, clean-up, throttle response. The entry-level fix.

  • •Cylinder Truing & Casting Cleanup
  • •Power Valve Mechanism Check & Calibration
  • •Deck Height Verification

Recommended For

Local Racing & Practice Bikes

Privateer Spec

The sweet spot. High performance, durable enough for a full season.

  • •Stage 2 Cylinder Porting
  • •Cylinder Head Machining (Squish & Combustion Chamber)
  • •Exhaust Port Polishing
  • •Carburetor Taper Bore

Recommended For

Regional Championships & Competitive Stock Class

Best Performance

Factory Works Spec

No compromise. Maximum power, exotic coatings, extensive labor.

  • •Stage 3 Full Race Porting
  • •Engine Case Matching (Blueprinting)
  • •Ceramic Coatings (Piston Crown & Combustion Chamber)
  • •ISF Process Transmission Tumbling
  • •Dynamically Balanced Crankshaft

Recommended For

Loretta Lynn's, Mini Os, Pro Nationals

Common Questions: KTM 250 SX Platform

Can you make my 250SX smoother for woods riding?

Yes. We use a different head profile (lower compression ratio) and conservative exhaust port timing to make the bike tractable in low-grip situations.

Why balance the crank on a 300?

The heavy piston of a 300 creates significant vibration. Balancing the crank assembly not only saves your hands from numbness but frees up horsepower lost to parasitic shaking.

KTM 250 SX & 300 XC Race Engine Builds