Spark plug

My bike is running rich or lean or optimum

Possibly a tad lean I would say.

It's not as simple as just looking at color to judge mixture. The mixture could be lean or rich in certain throttle positions and just the opposite in some other throttle positions. You need to do plug chops at specific throttle positions in order to properly judge mixture using plug color as the measure.

Plug chops are impractical. You can't exactly ride a bike at the constant rpm required to check each jet without dropping into pilot jet territory several times in the length of time it takes to colour a plug accurately and then stop the engine, coast to the hard shoulder and check the plug colour on all four after each run.
If you want to be pedantic about it a dyno is THE only way to set carbs accurately.
However, as the majority of us don't have access to or want to spend the money to have a dyno test done the most practical way is to read the plugs once they have been on a "Typical" ride and adjust them so they are good after a "typical" ride.
The chart I have posted gives a good indication of where there should be after that "typical" ride.

Warren3200gt wrote: Plug chops are impractical. You can't exactly ride a bike at the constant rpm required to check each jet without dropping into pilot jet territory several times in the length of time it takes to colour a plug accurately and then stop the engine, coast to the hard shoulder and check the plug colour on all four after each run.
If you want to be pedantic about it a dyno is THE only way to set carbs accurately.
However, as the majority of us don't have access to or want to spend the money to have a dyno test done the most practical way is to read the plugs once they have been on a "Typical" ride and adjust them so they are good after a "typical" ride.
The chart I have posted gives a good indication of where there should be after that "typical" ride.

Thanks. I've often wondered about plug chops. Some recommend running the bike at full throttle then shutting it off and checking the plugs. The problem I see with that approach is the fact that other than perhaps 1/4 mile track use most bikes will spend far more time running at less than full throttle. So should a plug chop be done after a typical fairly long ride on the street? I don't think I've ever seen that recommended, but that still would not show how the plugs looked at various throttle openings. Ed

I have also read that ethanol make reading plugs unreliable. Seems like color tune or exhaust sniffer on a dynamometer are more reliable. A sniffer mounted to the bike, recording while the bike is being ridden seems better yet.

Not sure if it works but I've read about guys that pull off a couple of spark plug caps as a way of allowing them to use more throttle for performing plug chops.

Plug chops are only useful to tell you if you are way way off. Once you get anywhere near close, plugs will be ambiguous as to which part of the jetting is causing the majority of the color. Again, only useful if you are pretty far off.

A good jetting will produce a good plug color, but good plug color does not mean all parts of the jetting are good.

If you are doing seat-of-the-pants jetting (which is how it was done back before wide bands etc,) the best method is to use the throttle to go lean and rich as you would on a practical ride. The instructions for this were spelled out nicely by Dynojet many years ago. There is a copy posted on the Tk22 site:

s3.amazonaws.com/gpzweb/TK22mainPage/TK22jetKit/TK22jetKit.html