I have a lt 160 john deere it has a 17 hp motor ,will not run on high,but will run on slow and medium but the muffler get so hot it will burn a hole in the right tire that how hot it get it a little loud ,just got this mower a couple ago looks like a new one what should I look for or do thanks ricky

Check the valve clearance and adjust if necessary.

If this is a kohler motor,you might check the muffler sounds like the baffle inside it came loose.

Hi,
Symptoms described point to the flywheel key. Overheats because timing is off. Cause is shutting down engine while revv'ed up. Replace key and throttle down for 20 seconds before shutdown.
Peace,
Clarke

Are we talking about the key in the fly wheel ,I check it seen to be goood ,could it be causr the baffle might be rusted out of the muffler it is real loud ,causeing the mower to get hot ?

Check the valve clearance and adjust if necessary.

This would be my next step