I have 2 King Quad 300s '01 and '02, they each have less than 150 miles both bought new. I mainly use them around the house, never going to far just normal yard work, playing etc. Whenever we take them riding for any length of time on the trails, when we shut them off they won't start easily, if at all. They seem to be running hot to me when riding, I feel a fair amount of heat throught the seat but the oil temp light never comes on. We have had to have each one of them pulled out of the woods for not starting after we have shut them off for a break. I've had them to the dealer and they can't find the problem. The fuel vent line is clear on the gas cap but they act as they are having some kind of vapor lock and not getting fuel. When I do get them started after they cool down some they have large amounts of white smoke, sometimes backfire and sound like they are bogging down. I have changed to different gas in both of them trying to find something that makes a difference. Some people have mentioned to me they may be getting to hot and Boiling the gas in the carb or something. I been told anything from cooling fans, jetting the carb, or adding synthetic oil to them, I don't know where to start. Any suggestions of what to check that would make me a much nicer guy to go riding with. I'm getting fed up of having two nice looking fourwheelers and having to be towed out by my friends. Thanks

 

I have a 2000 King Quad LTF300F and it had the exact same problem. I purchased it new in 2000. I live at 8800 feet altitude and typically ride 11-12000 feet. I had to push it down the pass several times and took it back to the dealer 4 times for rejetting. The shop owner finally came in and determined that the fuel was 'percolating' (boiling) in the carb. He had his mechanics install a high-CFM fan for $320. That fixed the problem and I've not had any trouble since. What you cannot do with the fan is have it running while fording deep water. In other words don't run the fan if you are going to or have submerged it.
Michael

 

try turning the gas off the next time you turn it off. then start it, then turn the gas on. might be flooding the carb.