I've a 2004 low miles Kodiak with the 421cc engine. It wouldn't slow run well, now won't start at all. Checked plug, good spark, suspect dirt in carb as my wife (who uses it) ran it on reserve tank a little. Took carb off, cleaned the jets I could see, seemed okay, no dirt apparent but still won't start, not even firing. Plug is getting very slightly wet, but not as much as it should. I have the workshop manual on DVD but it's almost useless as it just gives exploded drawings for the carb. I'll try a complete carb. strip next, but can anyone a) suggest something or b) suggest a Mikuni information source? Also, I can't figure how to remove the cables from the carb... Doh! Many thanks.

 

Im assuming you were using the choke?
The only jet which will cause your problem is the pilot jet, also known as the idle jet. It has to be unscrewed, and removed. Look thru it, like you were looking down a drinking straw. If you cant see light coming thru the center hole....its plugged and the easiest solution, is to just buy a new one. Go to just about any motorcycle/atv dealer, and they should be able to get you a new one for under 7 bucks.
Running on reserve, probably didnt hurt a thing. The jet plugs up, because the float bowl was left filled, and the gas evaporated,refilled, evaporatd, refilled, and condensed and left dried deposits inside the tiny hole of the jet. Next time the quad is parked....turn the gas valve to off, and let the motor idle til it dies.( this leaves the float bowl dry and clean) Now the jets wont plug. When you want to start it up the next time. Turn the gas to on, shake the machine slightly for a few seconds ( to allow the gas to fill the float bowl), and itll start right up.

 

Hi, many thanks for your reply. The choke is never needed on it and we've had it from new. The plug doesn't get sooted up, surprisingly, as I expected it to be running rich. I unscrewed and looked through and blew through three jets, all clean, but I'll recheck tomorrow. The Kodiak is used every day and there were some small brown deposits inside the float bowl, though more of a stain than gritty stuff. It was left for over a week since running properly as we were on a trip.

Happy New Year from Scotland! (in the country near Loch Ness) Believe it or not, it's 00.10 and there's a bagpipe player strangling cats over the valley. Folks are letting off fireworks and there's a thick mist, they won't be able to see a thing...

 

This is driving me nuts now. Today I removed all four jets, including the pilot jet, not a trace of dirt in there. The diaphragm in the top looked okay, the float and needle looked okay. After a long session trying to start it, the plug was only slightly wet and the engine fired once after about 10 revolutions. So, I figured the float needle might be sticking closed, so I removed it again, connected the fuel tank (over the 'bars) and with the float chamber removed, the needle seemed to work and stop the fuel when the float was pushed up. I put it all back together and there was gas everywhere, the float chamber was overflowing.. So it got pushed to one side and left for a day with more patience.
Coincidentally, I have two buddies, both with the same ATV as mine. All of us have difficulty starting them at times. One is so bad the guy reckons his is a cunning method of revenge by the Japanese for WW2...