You have to turn the carby around so with the blades on check that it wont strike the carby, Make sure all bolts are secure. I use a old towel and keep it under the exhaust to collect all the fuel and oil.I also make a template out of cardboard and place it in between the carby and head the amount of air that the blades turn out cools the engine to much...all my engines get the first 800ml to a liter on the bench where i can keep watch and heat into the engine... Then in the car..