Hopefully this will help you. The charts I have and have used successfully for my own stuff say this..............And remember
THESE ARE APPROXIMATIONS (not gospel) for stock applications. So here is what I can tell you.
For every 1000 ft you go above your factory setting (Usually 0 to 1500 ft above sea level) you need to reduce jet size by 2 percent. Then for every 20 degree temperature rise you can reduce by another 2 percent. Remember, this is a percentage of the factory jet size. So by my calculations if you are riding at 5000 ft. that is 3500 ft over the factory setting. So a reduction of 5 or 6 percent would seem safe. Then if the temperature is taken into account maybe another 2 percent reduction would be ok. With both factors added together a jet reduction of 7 to 8 percent would be tolerable. So if the factory jet was a 145... minus 7 percent of that (which would be around 10) that should give a proper jet size of 135.
Now to make it a little more complicated you have to factor in the use of the K&N filter which would require a slightly richer mixture. So I think to be safe you probably shouldnt go below a 138 or so then fine tune it with your needle clip.
I usually start in the middle position and work up or down from there.
These are general starting points but with time and patience in your tuning you will get optimum performance and with that optimum pleasure from your quad!! Good luck !!

 

TxDoc2
That's what I said.

 

Thanks for the info TrailBoss, The lowest I have gone was a 143 main so I will try a 140 and see how it goes on saturday.

Again thanks everyone for your time and ideas in helping me with this.

later.

 

If nothing else has changed, it should be easy to lean the motor a wee bit and quit fouling plugs (+ get some power back).