KTM 85 SX Platform
In the 85cc and Supermini classes, the physics of airflow change drastically. We are pushing these small cylinders to 14,000+ RPM. At these speeds, boundary layer separation in the transfer ports kills power. Our Factory Spec packages involve extensive epoxy work and reshaping of the transfer tunnels to maintain laminar flow, ensuring your Supermini doesn't just rev, but actually accelerates at high RPM.
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 85 SX Platform
85cc 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: KTM 85 SX Platform
What is the difference between a Mod 85 and a Supermini build?
A Mod 85 retains stock displacement but maximizes efficiency. A Supermini often involves boring and stroking, which requires completely different port timing to handle the increased piston speed.
How often do I need to do top ends on a Factory Spec 85?
High-performance engines demand maintenance. We recommend rings every 10-15 hours for peak competition, though our balanced cranks significantly reduce wear on the bottom end.