Originally Posted by Chris Peralta

I looked a little closer at the Rally 9 and it looks like it comes with the carb that is on the lower end engines so it's not the really good carb that comes on the B9 or the WS9. The bore and stroke are the same between the B9 and the R9 but they do use different piston/sleeve and a different crank. Most likely the power curve is going to be different and may not be ideal for offroad racing.