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Kawasaki MX & Off-Road Dirt Bikes
04 KX250 Fouls Plugs Often / But intermittent
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[QUOTE="DanAKAL, post: 924627, member: 41820"] Were this my bike I would start by trying to eliminate possibilities. From what you have here you suspect two things. Carb jetting and burning oil. Lets eliminate one of these if possible. Tranny oil: Forget about looking in that little window. Drain the oil from your tranny and refill measuring how much you put in. If it requires 700 ml then measure it and put it in. Ride the bike for awhile and drain the oil. Measure how much you drained to see if the bike is truly using oil. If it is then determine where it is going. Without external leaks water pump and crank seals are the first places to look. Carb Jetting: As always start with a clean air filter and fresh fuel mixed at whatever your favorite rate is and whatever your favorite flavor of oil. With the bike shut down turn the air screw in counting the number of turns until it is all of the way in. Return the air screw the same number of turns until it is at its original starting point. Start your bike and adjust it up to a high idle. Increasing the idle set point works best. Adjust the air screw out until the idle increases to its highest RPM and turning the air screw further does not increase RPM. A tachometer is best for checking this but not many KX’s have tachometers. You’ll just have to listen to the engine. After you do this a few times you’ll get the hang of it. By turning the air screw in or out you will begin to hear the changes in RPM. These changes will be subtle so listen closely. Adjust the air screw in or out until you have found the point where turning it in will decrease RPM and turning it out will not increase RPM. Shut down the engine. Turn the air screw in counting the number of turns until it is fully against the seat and will go no further. Then turn the air screw out the same number of turns as it took to get it against the seat. If it required two full turns or more to get the air screw all of the way in then the pilot jet is too large (rich) and should be replaced with a smaller jet. If it required one turn or less to get the air screw all of the way in then the pilot jet is too small (lean) and should be replaced with a larger jet. Replace pilot jets as necessary and continue this procedure until your air screw is between 1 and 1 ¾ turn out. At this point your pilot jet is of the proper size and no further attention need be given to the pilot. The only method that I know besides vacuum gauges to check the main jet and needle position is by riding the bike. I go more by feel of what the bike is doing than anything else. Is the response sluggish or crisp in the mid or open throttle? Sluggish is a rich condition and crisp is lean. We all want a bike that responds quickly and fast. This is the condition we are trying to reach. However, response like this is obtained by leaning the fuel. We want to take it up to the point where it is lean but not so lean that it will damage the engine. I know my bike is lean when it is hitting very hard and feels like I am barley able to hold on to a big dog on a leash. Also, the radiators are quite hot. So much that I can feel the heat through the shrouds and my pants to my knees. DO NOT OPERATE THE BIKE IN THIS CONDITION! A few minutes, 3 or 4, of riding time will tell you quickly the bike is too lean. If riding your bike feels pretty good or you aren’t sure really what is going on then change the main jet and see what happens. As you change jets the response of your engine will change. Don’t do anything radical like six jet sizes. Just change one jet size and see what happens. If nothing then change another jet size in the same direction of lean or rich. Usually no more than two sizes will produce a different response from your bike. Keep doing this until your bike is lean then go up one jet size and see what the response is like. If it is still lean then go up another jet size until you find the one that provides the response you want without being too lean. After you have the main jet you want do the same procedure for the needle position. If you aren’t sure then change the clip position. Raising the needle will make the mid range richer and lowering the needle will make it leaner. There aren’t many bikes that have the needle clip in either the #1 or #5 position. Almost all of them are in the middle three. When you feel you have the main jet and needle where you want them run the bike and chop the throttle. Pull the spark plug out and it will tell you what is going on. Always error on the side of being too rich as this only fouls plugs where lean can burn pistons. The starting procedure that your dealer is telling you is the same procedure I have been using for almost thirty years of racing two strokes. The problem is that in order for this to work the bike has to be jetted properly. A rich bike will produce untold of starting problems. I once lost 44 minutes in an enduro trying to get my bike restarted after I stalled it. That won’t happen to me again! I only had six points until this happened in the last twenty miles of the race. Cold Bike: -Choke On -Don’t touch the throttle -Roll the kick starter over easily five or six times -Crack the throttle and kick it like you mean it! (Bike will usually start the first couple of kicks if it doesn’t start when you are just rolling it over) -Choke off as soon as the bike is running (Keep the engine alive by blipping the throttle) -Don’t let it idle more than 15 to 20 seconds until you get it moving. Warm Bike: -Crack the throttle and kick it like you mean it Hot Engine: i.e. at race pace - Fully open the throttle to get in as much air as possible and kick it like you mean something! These are the things that I do regardless what color or size my two stroke bike is. They have worked on everything from 125’s to 500’s. One of the biggest things about most of this is experience. It is very difficult to explain experience but as you go you will learn how to tell what your bike is doing and why. By knowing these you will learn what to do to correct problems. Dan [/QUOTE]
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04 KX250 Fouls Plugs Often / But intermittent
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