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Kawasaki MX & Off-Road Dirt Bikes
KX65 plug reading after full engine rebuild - with pics
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[QUOTE="Rich Rohrich, post: 1459046, member: 16241"] Unfortunately you can't read a plug from running it the way you've described, there is way too much overlapping of circuits to pin point any area other than wide open throttle (WOT). You can reliably read the main jet and timing with a fresh plug and a loaded (like a slight uphill) WOT run for 10-20 seconds. It's important to try and chop the throttle at the end of the WOT run, and pull the plug. Part throttle running back to your pits just confuses things if you are trying to get an accurate plug reading. All you can really tell from the pictures you posted is the plug is running a bit cold for the load you are putting on the engine and not burning off the deposits. This makes sense given that you were running it easy with a minimum of load. Richening the jetting to try and color the ceramic will just make it a slow burbling pig. The color on the nose of the plug merely indicates the plug running temperature. It may need more fuel but you can't say for sure by looking at those pics. As Gomer suggested, you should change the jetting based on the way the engine responds for the low speed and mid throttle positions. You can not read the plug to determine the fuel curve in those areas, so it's not worth wasting your time. You can use a plug reading to determine WOT jetting but that's about it from a jetting standpoint. The plug can tell you a lot of interesting stuff about what is happening in the engine, but sadly low and mid throttle jetting isn't on the list. Fuel requirement is a function of load and throttle position, technically manifold pressure but that tracks pretty closely to throttle opening. That's why you can't really tell anything useful about your jetting by blipping the throttle on the stand. In a crisp running engine a plug running at the correct temperature should look more like this. Whitish with just a touch of coloring : [IMG]http://dirtrider.net/forums3/attachments/ltm_9_noshell_drn-jpg.4932/[/IMG] The picture below is a plug running a bit too cool. The setup is safe safe but not as sharp as it could be. The plug pics you posted shows a lack of heat and that's what causes the coloring, not the jetting. As you add more fuel you will cool things down further in the chamber so it will add more color, but it isn't any indication of the jetting. An overly lean engine with too cold a plug can have coloring similar to the plugs you posted. All it's telling you is the plug isn't running hot enough to burn the deposits off of nose of the ceramic. [IMG]http://dirtrider.net/forums3/attachments/plugd_noshell-jpg.4930/[/IMG] Start rich on the pilot and needle settings and carefully lean them till the engine has the required throttle response you are looking for. Except in very special circumstances you can't hurt the engine by going too lean on the pilot or the needle setting. The worst thing that will happen is the engine will bog or feel flat. Here's a link to Eric Gorr's Carb Tuning article. It's the best explanation of the process you are ever likely to find. Happy Tuning ! [URL]http://dirtrider.net/forums3/threads/carburetor-tuning-intro-by-eric-gorr.184616/[/URL] [/QUOTE]
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Kawasaki MX & Off-Road Dirt Bikes
KX65 plug reading after full engine rebuild - with pics
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