I've seen this complaint many times here,and the other day I ran across an article on roller chain drive designs. In it he says that any sprocket has a "top speed" and after that power falls off!! Maybe it's the sprocket not the engine? Alright I don't know how to do a link but follow these steps 1 Google "Standard Roller Chain Drive Design" 2 First entry should be "Mechanical Design Handbook:Standard roller chain drive design 3 Click on here. 4 Read the article, but what I'm talking about is the paragraph above the drawing of Lubrication Methods Let's see what you genius' think, if anyone wants to make an easier link feel free. Happy Thanksgiving Walter F.