TFC S-1 High Power Camshaft - GY6 Big Bore Builds

Maximize the power potential of your GY6 big-bore build with the TFC Special S-1 High Angle Camshaft. Designed specifically for engines running 58.5mm to 63mm cylinder bores, the S-1 delivers 6mm of valve lift — significantly more than a stock cam — keeping the valves open longer and pushing them further to pull in more air and fuel on every stroke. The result is stronger mid-range and top-end power that a big bore cylinder alone can't fully unlock without a matching cam upgrade.

This is the cam to run when you've already installed a big bore kit and want to extract the full power it's capable of. Pairs well with a high-flow head, performance exhaust, and upjetted carburetor.

Specifications

• Cam Profile: TFC Special S-1 high angle
• Valve Lift: 6mm
• Intake Lobe Diameter: 26.75mm
• Exhaust Lobe Diameter: 26.35mm
• Cam Gear Teeth: 34
• Cam Bearing: 6002C3
• Model Fitment: 58.5mm–63mm cylinder bores
• Made in Taiwan by TFC

Compatibility

Designed for GY6 QMI/QMJ 152/157 (125cc/150cc) 4-stroke engines running big bore cylinders from 58.5mm to 63mm. Not recommended for stock 57mm bore engines — the aggressive lift profile is optimized for larger displacement builds.

Build Tip: The S-1 cam works best paired with a big bore cylinder (61mm–63mm), a high-flow or big valve head, performance exhaust, and an upjetted carburetor. Running a high-lift cam on a stock head with stock jetting will limit gains and may cause a lean condition at high RPM.

This product is intended for off-road use only and is not legal for use in California on pollution-controlled vehicles. Check local laws before installing. Performance upgrades are not covered by warranty.

California Prop 65 Warning: www.p65warnings.ca.gov

• 6mm valve lift — significantly more than stock for stronger mid and top-end power
• High angle S-1 profile optimized for 58.5mm–63mm big bore cylinders
• 34-tooth cam gear, 6002C3 bearing — direct drop-in for GY6 QMI/QMJ 152/157
• Not recommended for stock 57mm bore — designed for big bore builds
• Made in Taiwan by TFC

Profile: TFC Special S-1 | Lift: 6mm | Intake Lobe: 26.75mm | Exhaust Lobe: 26.35mm | Cam Gear: 34T | Bearing: 6002C3 | Cylinder Fitment: 58.5-63mm bore | Engine: GY6 QMI/QMJ 152/157 | Origin: Taiwan

GY6 125cc and 150cc 4-stroke engines (QMI152, QMJ157) running 58.5mm-63mm big bore cylinders. Not recommended for stock 57mm bore. Off-road use only.