[wacio]

I left original 15 tooth sprocket in place. These engines are not pressure lubricated (10 psi oil pump just squirts oil on the moving parts). All crank shaft bearings are roller bearings. This type engines are designed more to run at higher rpm rather than higher loads. As proven by many there is no top speed gain to be had, just weaker acceleration netting performance loss. The only reason to to the swap is to limit vibrations at cruising speed. But vibrations are minimal any way (thanks to balance shaft).