Snowmobile Repair: Sled wont idle, yamaha v max, new inlet

Question
I have a 1995 Yamaha V-Max 500cc snowmobile.I started it up drove for about 10 -15 minutes then shut it off. About an hour later started it again no problem and drove for 15 minutes.  But, as I was driving it the engine wanted to stop when I was at slow speeds or if I got off the throttle.  It did eventually stop.  I couldn't get it to restart so I changed both spark plugs.  I was then able to start it but after driving for a few minutes the same thing happened.  It just doen's want to idle at all.  The only way for me to keep it running is to stay on the throttle.  Any ideas.

Answer
Hello Mark,

  Sorry I wasn't able to get back to you sooner. I am about positive your carburetor is ready for a cleaning. Especially the inlet needle and seat. Removing the carbs on those sleds can be tuff. You may only be able to remove the carb partially, enough to get the float bowl on the bottom off. Here is a diagram of the carb http://216.37.204.202/yamaha_oem/YamahaSnow.asp?Type=13&A=97&B=9  .  With a good cleaning, and maybe a new inlet needle and seat, you should be good to go. After cleaning the carb, you may want to run STP additive for a little while. Hope this helps. Let me know if you have any other questions. Good luck with the sled! --Arcticatman