Yamaha rhino problems

It might be the spark plugs or plug , but it looks like a fuel, pressure, filter,and injector problems Changing the plug is really easy. If it still occurs , change out fuel and then check the fuel pressures.

It takes fuel, spark and compression to run. Check compression to verify within spec..

why do you think you should replace the rotor?
that is a parking brake and is not used to stop
but however if you do this is a big Job best I remember

gasoline..I have had people bring in numerous atv's/motorcycles with empty tanks...(swearing they have gas!!)..next is to make sure you are getting gas to the spark plug (NEW ONE) and gas is getting to the fuel system.

sounds like the decompressor has broken

First, Disconnect the battery.
Find the old one... R/R all the wires to the EXACT place on the new one.. Got a smart phone.. take several pictures,, make notes with colors and locations..

Its not a hard job!!

Worn or broken piston rings or warn valve guides. A compression test will let you know which one.

sounds like you are hitting the rev limiter. If it launches that hard im guessing you have a belt or clutch issue.

STOP TRYING TO START THIS ATV!!!

..Sounds like the valves are hitting the piston!!

Did you/your mechanic check the valve to piston clearance at max valve lift/PISTON HEIGHT??..you need at least .035" (.89mm) on the intake and .060" (1.5mm) on the exhaust.- MINIMUM - . THIS IS CRITICAL!!!

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.....11:1 is a pretty tall compression ratio. Are you racing this atv?.. one thing you will find out is that you NEED TO RUN HI-OCTANE fuel..NOT airplane fuel either (its got antifreeze and other additives you so not want to deal with)..11:1 might require a 110 OCTANE race gas to get it to run right... make SURE the timing is RIGHT!!..with this much compression the right fuel, timing, valve clearance, cam timing, etc, MUST be perfect!!!