i also think its the rev limiter but there is a way around the reverse rev limiter when ya put it in reverse pull in the clutch twice and give it the gas or well thats how i can get around it on mine well at least it seems like the limiter doesnt kick in then

by the way im not an english major and im at work so i know i probably misspelled quite a few things but that doesnt discount what i say bacicly what im saying is before ya knock what i say try it out

 

So pull the clutch lever twice, get into reverse, hold throttle wide open and dump the clutch??

 

put it in reverse then give it a little gas then clutch twice and then you should be able to go full speed in reverse and with that you should start saying your prayers cause the raptor goes pretty dad-gum fast in reverse