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I just purchased a 2020 Grasshopper 729, having just sold my 2000 721. One noticeable difference other than more power and speed is the exhaust noise. On the 729 the exhaust sounds as if you are next to a wall and the exhaust is bouncing off it, that is when you are wide open throttle with the mower engaged and going about half speed. I find it somewhat annoying. My 721 had completely different exhaust noise, both had/have the 3 cylinder Kubota water cooled engine. One difference is the engine and muffler on the 721 was in an open area while the 729 the engine and muffler is in a full enclosure. What have others experienced. One other item, it seems the 729 uses more gas than the 721.

I now see that the exhaust muffler glows bright red/orange inside the muffler. I don't believe this is normal, will call service department to repair.

Service department found the problem. One of the coil packs was defective causing the engine to run on two cylinders instead of three. the unburned fuel from the deactivated cylinder was burning in the muffler. This Grasshopper was purchased new several months ago and now has 14 hours on it and has been running on only two cylinders the whole time.

The service shop is not concerned about the possibility of gasoline in the oil, gasoline washed away oil on piston/cylinder possibly scoring cylinder or burning out the muffler. I am concerned about those, what are your thoughts.

I'd be a little bit concerned. Did they tell you which cylinder wasn't firing.? Remember that as it could could come back to haunt you.
Hopefully not.?

Be sure the work order says one cylinder wasn't firing on brand new unit, and keep that work order till warranty is over, one thing i would do is contact Kubota and tell them what happened and ask for an extended warranty on engine, they might not do it, but they might.
that way if engine problems show up at end of warranty both you and Kubota have a record of it.
My thought on it is it might have washed oil off cylinder causing scoring which will cause oil consumption, if it is still at Dealer ask the to bore scope the cylinder that was dead to see how it looks, other than oil consumption it could have damaged piston rings but that is less likley.
if it starts using oil take back to dealer and call Kubota.

I was told they did contact Grasshopper and was told the Engine has a two year warranty and nothing further needed to be done. I did ask for the Grasshopper to be replaced or at least the Engine.

I would run a compression test on all cylinders and see if the non firing cylinder is different than the others.

Got the Grasshopper back yesterday, in the process of mounting the enclosure and snow blower. Did send an email to Grasshopper technical department to advise them of the issues, still waiting for a reply.

Some interesting reads....

I'd guess with the cylinder not firing and the actual much lower cylinder pressures and temperatures the engine would not be damaged at this point. Pressure and splash lubrication should have kept wear to a minimum, maybe even less than the other two cylinders that were doing all the work. Really good that you discovered this too!

Thanks for all of the replies. Still waiting for a reply from Grasshopper. Got the snow blower and enclosure mounted. Now some other questions. The engine now idles very high, prior to the fix it idled low or normal in my opinion, also when you mow etc. do you run with the throttle wide open, the reason I am asking is that this engine even when it was running on two cylinders had more power and had twice the speed that my old year 2000 grasshopper had with also a 3 cylinder Kubota gas engine.

Then your 2000 Grasshopper must've been very sick.

If someone set the idle with it running on two cylinders, is it reasonable to assume that the idle speed would be correspondingly higher when the third cylinder became active? It should have been readjusted at that time.

I don't know how much confidence I would have in this dealership. It would have done that at the dealership and they should have adjusted the idle without having to be told to do it.

The difference between the 2000 and the 2020 is hp 23 vs 29. I spoke with a Grasshopper Technician from the Grasshopper Factory this morning he advised that he didn't believe it hurt anything but he would have changed the oil. The muffler is now a catalytic converter and it should be alright also, he also advised that normal idle is 1600 rpm which is quite higher than what I was experiencing when it ran on two cylinders, which is to be expected.