I just replaced the engine in my lawn tractor with a new 26hp B&S v-twin vertical mounted engine. When I advance the throttle from slow to fast, the engine surges, and I am unable to get full power. There is a rod near the throttle stop that moves up and down when the engine surges. When light pressure is applied to this rod, it stops moving up and down, the engine stops surging, and the engine acts like it is allowed to get its full power when the throttle is advanced to the fast position. Does the carburetor need to be adjusted? If so, how do I adjust it?

Clean the carb, and check the fuel supply.

Mowerman:

Thanks for your advice. I tuned the carburetor, by adjusting the screw, and it did the trick! Cheers!

-WacoTX