KTM 65 SX Porting & Performance Build
KTM 65 SX engine mods designed to broaden the powerband. Our porting specs reduce the need for constant shifting and eliminate the bog between gears.
The Stock Bottleneck
"Narrow powerband making it difficult to keep on the pipe between gear shifts."
The HP Race Dev Solution
"Broadening the mid-range torque curve to allow for 'short-shifting' without falling off the pipe."
We don't just "grind ports." We mathematically correct the engine's geometry to solve this specific flaw.
Engineering the MC 65 Platform
We modify the exhaust port roof shape to support over-rev without sacrificing the mid-range. A flatter roof profile allows for a wider blow-down window, keeping the pipe active for longer periods between shifts.
The 65cc transmission is prone to drag. We perform an Isotropic Superfinish (micro-polishing) on the gears to reduce friction, allowing for smoother, effortless shifting even under load.
Intake turbulence is a major thief of power on small bores. We case match the intake tract to the reed cage, removing casting flaws that disrupt the laminar flow of the fuel-air charge, ensuring instant throttle response.
Select Your Level
Choose the package that fits your racing class.
MC 65 Platform
65cc PlatformMinimum 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
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: MC 65 Platform
Why does my stock 65 bog on landings?
This is often float bowl turbulence combined with weak intake signal. Our intake tract porting increases signal strength to keep fuel atomized even during G-outs.
Can you fix the 'gap' between 2nd and 3rd gear?
We address this by carrying peak torque higher into the RPM range, allowing the rider to rev out 2nd gear further before grabbing 3rd.