i have a 2002 mxzx 440 that i bought, i put the low compression heads in, i have 310-300 jetting, 125 lbs compression, mixing my fuel 40/1, using octane boost off pump gas. i currently use BR9ES plugs but it is starting to foul them constantly, it will only foul them at low rpm, would a hotter plug help me out, it seems as though the plugs are blowing from being too cold, i am thinking of going BR8ES, what doyou think?

Drop your clip on the needle one slot to the number 2 spot. That should clear up your problem.

I may be mistaken, but arent you suppose to run around a 280 jet with the low comp heads?, also with the 12 to 1 heads 91 octane is more than enough, too much octane will cool you combustion temps down to zilch.

the skidoo bulletin i got said the jetting was to be at 310-300, as for the fuel im running 87 with octane torco octane boost, mixing it to add 4 points, so i am running 91 octane

dantrin, what your saying makes sense, the sled seems to run rich in the midrange.
hey ballsout, do you know anyone running theses sleds with 280 jets, i would like to come down but i wanna make sure im safe. i would be able to tell off the plugs but they dont last long enough to get a readable burn.

before you go fooling with your jets i'd try the br9eya's. my 99 ho was eating the br9es's and i switched to the eya's and I've only fouled one set in 1000kms. The worked for me, one of the mach guys told me about them.

i have a set of BR9EYA's that i had in my 670, i have one of them in the sled and its still going good, maybe i should give that a try
but i know for a fact its still pretty fat in the needles

I had the same problem with my 1999 Mxzx 440. Just drop the needle and it will take care of the problem. I would stick with the mains you got. Your sled has the power jet system so I would stick with what you got. You really dont need the octane boost. You could probably run it on 87 and be safe but that is up to you.

Hey make sure you are using a solid plug so that it has the metal cap. the aluminum caps will play hell on your plug caps. Gap the plugs to about .016-.018. All this stuff will make a difference.

hey dan, on your 99 how often were you fouling plugs? and what heads/fuel were you running.?

Before I changed the needle I fouled out two sets on my way home from work. I have low comp heads and run 87 octane.

how did your sled run wide open, mine is great at idle and at full throttle, but shes fat in the mid, but if it worked for you i will definetley try it, the way it runs at about 6000 rpm it cant hurt to lean it out a bit, thanks man.

common fix to that problem is to drop the needle.
Install clip on #2 position...leave pilot original.
Plug gap @ .016"


....if you need clutch kit, have information....
dynamo-joe@shaw.ca
dynamo617@hotmail.com

baddest 440 kit :thumbsup: