This article is an orphan, as few or no other articles link to it. Please introduce links to this page from other articles related to it. (December 2009)

A 4-stroke powervalve is a device fitted to 4 stroke engines that constantly adjusts the internal diameter of the exhaust system to perfectly suit engine revolutions.

This ensures superior low to mid-range performance (ca. 12-20% improvement), linear power output and reduced exhaust noise levels while the valve is in its reduced opening position.

• Yamaha EXUP (Exhaust Ultimate Power valve)
• Honda HTEV (Honda Titanium Exhaust Valve)
• Suzuki SET (Suzuki Exhaust Tuning)

This article about an automotive technology is a stub. You can help Wikipedia by expanding it. v • d • e