For getting an accurate main jet change reading... how far (or long) do you have to ride at 3/4 to WOT? I'm using a good used plug.

Can you use this same process at 1/2 throttle for needle changes?

I just put on a HMF with Quiet Core and the Noss Super Flow with Uni on a 2001 Wolverine. I started at a 141.3 OEM main jet, and have gone to up to a 150. I have ridden a couple of times about a 1/2 mi. at WOT, killed the ignition and coasted to a stop in between gears. I still think I'm lean or possibly I'm not giving the plug enough time to change shades??? The only carb change from the stock settings thus far, is the main jet (needle and idle air screw still at stock settings).

 

Not really an answer but one of these might help....

I'd like to know myself.....

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

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

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JETTING

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

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

 

a 1/2 mile is more than plenty to judge your main setting. Is the plug still white? you should be looking for straw colored insulator.

 

Thanks for the links. I found a couple I had not run across during my searches.

There seems to be a couple different schools of thought on WHERE to read the plug at for mixture. Some articles say the insulator near the tip is not an accurate indication, because if the heat range is correct, then it should burn off all the deposits. They say it should be Read down inside the plug where the insulator meets the metal shell. The theory being... the insulator is much cooler at its base and won't burn itself clean.

I just can't imagine all you guys are walking around, packing a lighted 10x magnifying glass. I looked at the plug closely before I made any of the mods and it looked nice and tan/brown on the ground strap tip and all around the insulator, near the tip. There was also a definite color change about half way up the ground strap, which I believe would indicate the proper heat range.

I don't see the tan/brown as of yet, with the jet changes I have made. That is why I was wondering how long it would take for an accurate color change.

Also, are you guys using a new plug or good used plug. There seems to be a difference in opinion there too.