I had the same issue of grass scorching with a two Toro ZTRs, with the 708cc Loncin engines. I tried to get off the grass, when not moving.
For the dust issue with the air filter, at least add a foam pre-filter over the stock filter.
If you want to spend some money, you can upgrade to a Donaldson style filter.
This kit includes everything you need to upgrade your Kawasaki FR series engine to the FX canister style air cleaner. Replaces air filter part number 11013-0752. This canister air filter setup greatly reduces the amount of dirt that accumulates around the filter by raising the air filter...
powerequipmentman.com
Good to see some one in the USA is finally offering the complete kit as a kit .
We have had them down here from day 1 but Oz tends to be lot dustier than most places .
When I fit them I do not use the metal FX blower housing as it adds a lot to the cost
As TimeCutters come with ROPS standard I buy a length of convoluted rubber tubing long enough to go to the ROPS and bolt the air filter to the ROPS
IT can be fitted vertical or horizontal, makes no difference to the filter
Inside on the right side seems to work best so it is sort of behind the seat
On a mower owned by a woman who has the seat full forward it is mounted to the seat bracket bolts .
Doing this makes it easy to remover the blower housing to do an annual fin clean which is a must if you bag
Spend the extra few $$$ and buy the flow gauge .
Do not touch the filter till the flow gauge is in the red
With domestic use you will probably never need to touch the filter for as long as you own it .
Stens, Rotary, Prime Line all do aftermarket filter elements .
I replace the OUTER only on the commercial mowers at around 1000 hours , this is well before the red zone
In 11 years I have never replaced an inner on any of them apart from the 2 skid steers and the Ditch Witch.
They get new outers around every 3 years or so and a new inner on every second outer but of course it costs then a lot more than just the repair if the equipment breaks down or is off the road for a week or more for an engine rebuild ( actually they just get me to instal replacement engines if I tell them a major engine job is needed , even if it is just a leaking sump gasket )
There are lots of heat shields available but if your mower is burning the grass as bad a you are telling us I would guess that it is overheating which causes it to run lean so the exhaust is a lot hotter than it should be .