To keep the valves working in unison, these Rotax-style valves use exhaust pressure to open and close the exhaust ports rather than cables that require adjustments.
Opening RPM can be tuned with an exterior adjuster. A pop-up indicator simulates valve action so tuners can synchronize and adjust the valve opening on a jackstand. The kit includes alteration of stock valves to fit the new valve assembly. Kits for Suzuki 800 and 900cc engines sell for $225 each. Supreme Tool & Machine, 248/673-8408; www.supremetoolinc.com.