http://powerfactorproducts.com/
"The 5-85 engines utilize the Yamaha OEM crankcase. The cylinders are OEM quality, Nickasil lined with triple exhaust ports. Comes with PowerFactor billet aluminum girdled head cover and domes."
"The 5-85 engines utilize the Yamaha OEM crankcase. The cylinders are OEM quality, Nickasil lined with triple exhaust ports. Comes with PowerFactor billet aluminum girdled head cover and domes."