I don't know what is ailing the Turf Tiger demo machine, but in the past I have serviced several TTs that had a clutch slipping, badly worn V belt on the clutch, or the tensioner spring had lost its pull. Moving to the deck area, there are more V belts with gear boxes and a drive shaft between.
On some newer machines, the high idle speed has been reduced to 3,200 to 3,300 RPM set by the engine manufacturers in the interest of extending engine life verses 3,600 RPM engines, this slows down blade tip speed substantially.
Over the years I have run across machines where the full throttle RPM has decreased due to cable and other problems. I readjust them to bring them back up to 3,600 RPM.
I have heard the comment the this is a demo machine and it needs to be brought into the service department and checked out, but they haven't had the time to do it. I've heard this "song" many times over the years. Years back I was interested in a used aircraft. I insisted that the aircraft be flown so I could evaluate its performance. During the runup I noticed that the engine wouldn't achieve full RPM, the pilot/seller commented that the engine/prop governor needed to be readjusted. I told him to return to the ramp as I was no longer interested in this aircraft. Most aircraft piston engines have two spark plugs on each cylinder and have two magnetos for powering each set of spark plugs, one magneto had failed, he knew that, but was still going to fly the aircraft with a perspective buyer on board, not a good idea especially from my perspective being an FAA licensed aircraft mechanic, the seller wasn't aware of this.
Anyway, just a few comments from Mad Mackie in CT:laughing::biggrin::smile: