O.K. I got this atv brand new and broke it in under stock conditions.Later put on K-n-N filter and white brothers exhaust.After a few rides could not get it to start ,so changed plug and it was black and dry(not gray or white).Placed new plug then after a few rides same thing,wont start . Plug is the same way(Black and dry).According to white brothers ,exhaust works with stock jetting and no rejetting is needed.It seems it would be running lean but the plug is not white or gray.Has anyone had this problem or know what is going on?After I clean the plug it fires right up. I do have some backfiring but usually when engine is cold.

 

Fouling

* Will occur when spark plug tip temperature is insufficient to burn off carbon, fuel, oil or other deposits

* Will cause spark to leach to metal shell...no spark across plug gap will cause a misfire

* Wet-fouled spark plugs must be changed...spark plugs will not fire

* Dry-fouled spark plugs can sometimes be cleaned by bringing engine up to operating temperature

Before changing fouled spark plugs, be sure to eliminate root cause of fouling

http://www.ngksparkplugs.com/techinf...31000&country=

Sounds like you need to get a hotter plug....With the K&N and pipe you probably should go up in your jetting

 

Why would I need a different jet/shouldn't it be running lean due to the pipe and k-n-N which would leave the plug white or gray/or is it because the exhaust and filter are allowing a bigger better bang but the plug is not hot enough?

 

I don't know really...have you checked the gap on your plug? A pipe and better air filter should create better and more airflow thus requiring more fuel...why your plug isn't white I don't know...but it's better to be rich than lean.

Here are some more links....maybe something will make sense.

Plug reading

http://www.motocross.com/motoprof/mo...lug2/plug2.htm

http://www.gnttype.org/techarea/engine/plugs.html

http://www.strappe.com/plugs.html

http://www.nightrider.com/biketech/spkplghnbook.htm

http://www.hioutput.com/tech/plug.html

http://www.victorylibrary.com/mopar/plug-read.htm

http://www.cyclewerksracing.com/reading_spark_plugs.htm

http://www.splitfire.com/plugtips.htm

http://performanceunlimited.com/illu...parkplugs.html

------------------------------------------------------------------------------------

JETTING

http://www.speedandsport.com/jet.html

http://www.dynojet.com/motorjet.shtml

 

Have you tried putting it back to stock to see if the same thing happens. If it runs fine stock, then rejetting would most likely be the solution. This would be due to an insufficient air/fuel mixture. A minor carb adjustment may do the trick also. Sounds to me like there is to much gas and not enough air. Also running a low octane fuel may cause your problem too.