Small Engines (Lawn Mowers, etc.): Higher Top end Please, fender clearance, hydrostatic transmissions

Question
Dear Sirs Please Help I have a Troy-bilt super Bronco with a Automatic tranny that's sick. I don't cut grass with this one but I do have a dozer blade on it. I'm a Disabled Vet "Can't Drive Car" But I can drive my tractor. I would like to have a higher top end. Any Ideas? Thank You

TONY FREEBIRD

25842 Streator Dr
Broken Arrow OK 74014-2739
Cell #  

Answer
It can be very challenging to change the speed on hydrostatic transmissions.  You options are:

1)  Change the pulley on the transmission input shaft.
   Issue:  Different size pulleys are hard to find and can be very specific.  Not likely to find an off the shelf part.  Custom made pulleys can be very expensive and you would probably have to change the belt size (length).  With the automatics even changing the input pulley may not change the high speed as some transmissions have a maximum RPM.

2)  Change the engine pulley.
   Issue:  Easier to find but the belt and max input RPM on the auto may not make a difference.

3)  Change the tire/wheel size.
   Easiest option
   Issue:  Costly to replace wheels/rims and tires.  Fender clearance?  The size difference would have to be significant to notice a speed change.

Other options:
Buy an older riding mower with a bad engine but has a gearbox with a sprocket output and a sprocket differential.  Swap engines and then source sprockets.  Sprockets are much easier to find as they are used in many go-kart applications.

Eric