Cylinder head upgrade. Features CNC machined port shapes, larger high performance valve seats and custom made valves. Valve sizes are increased from the tiny stock 33mm intake & 28mm exhaust to 36mm intake & 32mm exhaust. This is not a radical modification. These bigger valves bring the valve sizes up to what would normally be found on other brands of 650 singles.

Big Valve Heads are sold only on an exchange basis. We need your stock head for the next batch of modified heads.

 We strongly recommend checking valve to piston clearance when installing oversized valves.