Tilting the Needle

Ok, so i leaned out my KX100 needle one step, and the bike runs way faster and quicker. Before the plugs were wet and black, and it was all smokey. I notice a good power increase. New problem, the engine feels like it doesnt need to be leaned more, but the plugs say it does. I have put like 3 new plugs in, all black and wet... ? :naughty:

several things come to mind.

1) reading a plug is much more complex than i ever thought. dont believe me? i've read NUMEROUS articles on the subject, and this one is by far the best.

2) you might be mixing too much pre-mix (i am assuming a KX100 is a 2 stroke). always make sure you mix the EXACT SAME amount of oil every time. this removes one variable from a plug reading problem. on the same note, you might have a small oil leak in the main seals, this lets transmission oil in the cylinder (does it burn oil?).

3.) Get on the throttle. If you dont get your 2 stroke "on the pipe" (in the power band) its very easy to foul plugs. these engines were made to be (over) reved.

4.) Your plug may be too cold. All plugs have a "self cleaning" temperature. Carbon deposits are cleaned/burned off of the electrode once this temperature is reached. too hot of a plug will cause pre-ignition and damage your topend.

5.) Your needle affects your jetting at mid throttle (pilot/air screw/fuel screw/slow jet = off idle throttle. main jet = mid to full throttle). so if you leaned out your needle (that is raise the clip, which drops the needle), and rode back to your truck, you probably were going very slow and idling around when you killed the engine. so your new needle setting wouldn't "read" on the plug. to read the needle setting you should keep your throttle open at 50% and ride in a straight line (or make big circles) for a few minutes. then hit the kill switch while your throttle is still 50% open. that way idling back to the truck doesn't "erase" the reading. to read the main jet do the same thing at full throttle, to read the slow jet just keep it BARELY above idle.

6.) before you begin, write down EVERY setting on your carb (fuel screw is measure in turns OUT). make sure your engine is 100% warmed up before doing anything. make sure your carb vent tubes are cleared and not blocked with mud. make sure your carb is clean and not gunked up with varnish or gum inside the jets. make sure your airfilter is cleaned. dont try to do anything while the filter is still sticky and gooey with oil either. a brand spanking new plug is hard to read...make sure you have ridden around with it for 30 minutes or so before experimenting to break in a new plug. ALWAYS make changes ONE at a time to your carb and note the affect of each setting.

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