Snowmobile Repair: 1985 Artctic Cat Jag 440, plug caps, type of plugs

Question
I have a 440 Jag that starts easy, runs well but bogs down at high speed only when it gets hot. I have cleaned the carb, replaced the fuel lines, replaced the coil, new fuel filter, plugs, plug caps, fuel vent, check for muffler blockage. I als checked the timing which is suppose to be 18BTC and is showing 16 so I need to adjust that. Any othe thoughts why it would run lousy at high speed when hot only?  

Answer
Hello Steve,

  The timing could be some of the problem. The type of plugs you are using can have a large effect on the sled, also. The temperature outside also can affect it. If you are operating the sled in 20 degree weather or warmer, use a #290 MAIN jet. You can also use BR8ES plugs in that sled with out any trouble. Last of all, your seals may be getting worn out. Hope this helps. Let me know if you have any other questions. good luck with the sled! --Arcticatman