Black spark plug

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svtman79
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Black spark plug

Post by svtman79 »

I just pulled my plug. It was jet black, and smelled and looked like is was covered in gas. What would cause this? I just put new boyesen reeds in it and desert pipe on it about 5 miles ago. I plan on doing some carb tuning tomorrow. I have 3 mains and 3 pilots to play with other than the stock ones. I am running 50:1 motul 800 and 93 octane in it now. I have only put about 8 to 10 gallons through it since I have owned it. This is the first time I pulled the plug. It other wise runs great.
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canyncarvr
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Re: Black spark plug

Post by canyncarvr »

>|<>QBB<
svtman79 wrote:I just pulled my plug. It was jet black, and smelled and looked like is was covered in gas. What would cause this?
Engine is **most likely** running too rich.

It other wise runs great.

Nothing like it will when it's tuned.


**edit to be correct..but that's where my money is.
Last edited by canyncarvr on 12:26 am Dec 21 2009, edited 1 time in total.

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IdahoCharley
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Post by IdahoCharley »

CC is right - Lots of info on this site concerning jetting. Perform a search.

FWIW - Even a properly jetted bike can have a wet plug smelling like gas. Know what you need to do prior to pulling the plug for a plug check. New reeds and a quick run with a new pipe followed by a minute or two of putting around or just backing off the pipe and slowing down shifting through the gears will not give you a good plug reading.
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canyncarvr
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Post by canyncarvr »

That is a fact. A true one, too!

I stand corrected....and did.


The color of the plug doesn't tell you much of anything in the way of air/fuel mixture. Color comes more from temperature and fuel charactertistics (additives and such).

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