Snowmobile Repair: stalling, rich mixture, drive shaft

Question
my friend has a snowmobile that stalls out after 15 min. in order to keep it going you need to full throttle or your dead in the water.Wait 20 min. it works good  then  it starts all over again.1997 snowmobile. I believe he change the plugs, coil and all the easy things on it any idea. thanks Richard.

Answer
Hello Richard,

  I'm not sure what year make and model the sled is, so I can't  give any specific possibilities in those areas. What it sounds like to me, is the carb needs a very good cleaning, as it is most probably delivering a rich mixture and causing the plugs to foul. During the cleaning process, pay special attention to the inlet needles and seats. Another thing to check would be the crank seals. With the sled running and barely warmed up, spray carb cleaner behind the drive clutch so that it saturates the area where the drive shaft exits the engine. If the engine idles, or revs with the carb cleaner on it, the seals need to be replaced. If all else fails, use spark plugs one heat ranger higher, in other words if he is using NGK BR9ES he would change to BR8ES. Using cheap oil also fouls the plugs easily. hope this helps. Good luck with the sled! --Arcticatman