YZ65 Platform
The YZ65 entered the market with a massive advantage: the mechanical Yamaha Power Valve System (YPVS). Unlike its competitors, the YZ65 uses a ball-ramp governor for consistent valve opening. However, the stock port timing is often conservative to ensure reliability. We blueprint the YPVS mechanism to match our aggressive cylinder porting, turning a solid mini bike into a platform that pulls longer and harder than anything in the class.
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.
YZ65 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: YZ65 Platform
Does the YZ65 need a different pipe to work with your porting?
While we recommend aftermarket pipes, our 'Privateer Spec' is designed to maximize the efficiency of the stock pipe by matching the exhaust port duration to the pipe's resonant frequency.
Is the YZ65 mechanical power valve reliable?
Yes, but it requires precise timing. We shim the governor spring to alter when the valve opens, tailoring the hit for aggressive racers vs. flowy riders.