Jetting & Cold Plugs

[O'Deere]

W/o the air box on my jetting seems perfect (cardboard color on the electrodes). Install the airbox & suddenly the deposits go to a charcoal color. I've even gone to the next smaller size main jet (190) & cleaned the metal screen in the airbox but still just get a lighter charcoal color. Neighbor w/ believe it or not 104,000+ miles on a Polaris Indy tunnel (virtually everything else on the sled has been replaced multiple times) believes the BR9 plugs maybe too cool for my sled. Recommended running BR8s to get a more honest showing. He said that there could be to much 2 stroke oil in the mix messing up the plug reading. Any suggestions on this. Carb is a nearly new non powerjet VM34. Are there other checks I can make? Not exactly sure how to read carbon modeling on piston crown.

[O'Deere]

Going to try sanding off sharp edges in the intake track. Start w/ the air box to see what affect that has. Maybe the newer carb has sharper edges than an older 1. Also would like to heat & roll the mouth of the rubber snorkel. My F150 has a rubber "snout" at the beginning of the intake where the opening has rolled ends.

[SpitfireKing]

I don't think any of the JD sleds call for BR9's so I would go to an 8 forsure before I started sanding and heat rolling...they were never done like that from factory...so why change it now. DOes the sled not run right? If it's pulling strong and the plugs are a bit black who cares..it's fine...it's if their white you need to start worrying.

[O'Deere]

Hmmm. I believe I've been running BR9s all along. Have to check. That could be the problem right there.
Well as far as smoothing out the intake that might provide an opportunity for more power. Carefully watching the plug color of course & rejetting would be necessary if it does.

Thank you

[O'Deere]

No thats not right. The manual calls for N2 or QN2 Champions which cross to NGK BR9s.
Be nice to get a spark plug pyrometer or thermometer which ever it is to get the absolute best check.
After I went to the smaller 190 jet it felt as though the machine picked up some power so there seemed to be another indication I was way to rich w/ the 200. Just not trusting that plug reading.

[joshua16]

i have been running br9es's in my jdx4 special for four years and thay are the exacte crose for chapions

[SpitfireKing]

really? I ran some 9's in my 77 LF because it was all I had at the time...it HATED them...wouldn't idle right, and always fouling...I've used 7's and 8's and had way more success then 9's..only use 9's in newer stuff I have owned.