Plug check

1 reply to this topic
  • Jawmail

Posted May 01, 2006 - 12:17 PM


When you are checking for lean/rich conditions after rejetting do you have to use a brand new plug ? Do you just warm up the bike, go around the block, then turn it off. Any help is appreciated.


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  • rkuckkahn

Posted May 01, 2006 - 12:29 PM


I start with a new plug. Drive around until the engine is warmed up. Then I start a run far enough from my garage to run about 1/2 throttle for a minute (in a lower gear to match the local street speed limit) pull the clutch, kill the engine and glide to the driveway. Let it cool and check the plug for a nice warm brown color. You probably know that white is lean and black is rich (normally).

An older plug can also be a great indicator of engine ignition conditions. The condition of the electrode (the little thingy attached to the plug bottom) is helpful for longer term conditions like preignition, too hot/cool plug type, etc.

There are threads with pictures of plugs to help define what these are as well.

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