I have a 2004 Yamaha Kodiak 450, The speedometer (digital) displays motion (9-32mph) while idling in Park, when placed into reverse the engine starts misfiring badly, It stops misfiring when the speedo reads 0. Is this a common problem?

 

when everything was working find would it limit your reverse speed??probably to 10mph or something??? if your speedo is off your quad "thinks" your going to fast and slows it down witch would cause your missfire