OK, I have a bone stock '04 Baja X. When I hammer around our field/track where we ride all the time, the headpipes begin to glow red. Last week, I changed the plugs to ND Iridium's and the pipes glowed MORE red. Maybe about 1" further down the pipe. Also, it seemed to lose a little power ( I use my friends Raptor as a gauge). So I swithed back to the stock plugs and the glowing went back to normal. Today I installed a K & N filter w/prefilter. I was told that the bike had been rich because they all are from the factory and the glowing red was unspent gases. So I tested it tonight. The pipes glowed red all the way to the muffler guard!!!! Also, on decel the bike always backfires slightly.

All this leads me to believe that the bike is lean from the factory. Also, most companies make engines slightly lean because of reduced emmisions. I have a Dynojet kit that I'm going to install. All the jets in the kit are going up in size also, which also makes me think the bike is lean. It just doesn't make sense to me that the machine is rich when everything points to a lean condition.

 

atleast your air/fuel mixture screw is lean- turn it out until, the glowing goes away - will get rid off the popping on deceleration too.

 

Raise the stock needle to the richest position and go to a 170 (mikuni) main. Set the air screw at about 4 turns out. You'll like it. BTW leave the air lid on.



MrHorsepower