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Foreman 500 Ecosystem, Unifilter and Jetting

2130 Views 4 Replies 3 Participants Last post by  KAGRIFF
Last weekend, at 4500ft and at about 50*F I took the 500 for a full throttle pull up a long hill. Quad was running real good so I thought I would pull the plug to take a look. Running a DJ 165.

To my surprise, the plug was white/grey or lean. Air density at 100ft elevation with air temperatures around 75*F is 0.074lbs/ft3. At 4500ft at 50*F the air density is 0.066lbs/ft3. Most of the Florida guys seem to be running DJ 170's, yet with a way lower air density, I can't believe a 165 is so lean.

Am I missing something? Any help would be appreciated.

What are the guys that ride 500's further north or at higher elevations and using HMF pipes and high flow air filters using for jetting.
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Any help would be appreciated.

If the plug is tan/brown, its perfect.

We all run the 170s around here, like you said. The elavation where you would decrease your jet size is @3k ft. So you should be real good where your set now, ecspecial w/ the Eco pipe. Did you put in a new plug after jetting? Perhaps old crud on it?
Thanks for the reply. I have jetted a lot of sleds but this is the first time I have jetted a 4 stroke. I was using the stock plug. I will try with a new plug. The whole electrode was greyish white. I couldn't believe how lean the quad was. I might put the stock filter in and try that just to see where I am. I was using the third clip position. With our air temps here and elevation, our air density is lower than yours right until freezing. I was hoping to just use the 165 until freezing than put the stock air filter back in for colder temps as these things are way too hard to jet.
I am running a k&n and an hmf pipe. i run a 172 jet and it seem to be just right here in the higher elevations of the hills here in TN. My 07 in not hard to jet as i can change one in about 20 min. hope this helps with your bike and jetting question.

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