I think its a Warrior (black and white 350). Just bought ran fine on trailer, I put gas in it and now it idles great but as you give it gas it back fires and spits. it acts like the four wheel drive 4-wheelers when you put them in reverse and have to hold down that button to get them to back up- I have changed the plug etc. makes no difference- it will not run past idle even though 5-minutes before I unloaded it, it reved up fine. I did put a little crank case oil in it cause it looked low- could I have overfilled it? would that cause it to misfire? Help thanks! Daddy bought this for his girl "trying to make a boy" outta her- -dr

 

welcome! i would try asking this in the yamaha section of the forums.

 

Had you asked before your purchase, I would have recommended AVOIDING the Warrior!!!

Could be a carb problem. Never hurts to clean a carb anyway! Pay particular attention to the idle/slow/pilot jet. These get easily clogged by scum when the fuel sits in the carb. This makes you lean overall.

Another possibility is that the reverse rev limiter is sticking on. While I have not owned a Warrior in 15 years, I do recall that this was an issue with this machine! Don't recall the details, but you may find some old posts on this issue.

Again, head for the Yamaha forum.....