Slow mow

[Donnie Lee]

My Father-in-law recently got a 2004 troybilt super bronco. Joker drives slow. I adjusted belt tension on pedal, helped a little. We then noticed that someone took out the 21hp engine and installed a 17hp engine. Is it possible that the drive pulleys are of different diameter, causing the lack of speed?

 

[Arwing64]

The drive pulleys would be a big factor in the mower's speed. It's all about the ratios. Assuming that this has a hydrostatic transmission, it would go around 5 MPH. When the engine was swapped, the pulley sizes must have also been changed. The pulley on the front probably has two pulleys. One for the transmission and one for the blades. The front pulley might not be the one that matches the tractor. If it is, then the rear pulley is too big. If it isn't, then I assume the belt must be stretched out and it can't grip the pulleys very well. The engine itself should not dictate the speed of the tractor.