Is my jetting good? (spark plug pic)

3 replies to this topic
  • iamadam1122

Posted August 21, 2009 - 11:39 PM


2008 YZ450F
FMF megabomb/carbon 4.1 full exhaust
stock jetting
Sea level HOT outside. if that makes a difference

Does this look ok? Only ran it for about 30 minutes, is that long enough to check? It seems harder to start now that I put the pipe on. Thanks.

It looks a little lighter in real life, but not much
Posted Image

  • grayracer513

Posted August 22, 2009 - 07:48 AM


If you are using unleaded gas, you cannot read spark plugs and tell much of anything regarding jetting. Even if using leaded fuel, the only thing that will mean much is if you chop the throttle at the end of a full throttle run and kill the engine, then remove the plug before it's run any more.



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  • davcon

Posted August 22, 2009 - 09:10 AM


Just for comparison.

50-60 degrees, 5000' elevation
Stock jetting

  • iamadam1122

Posted August 22, 2009 - 09:11 PM


Ok, makes sense. It runs fine other than being hard to cold start. Does this mean everything is good? I dont want it to be super lean and blow up or something.

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