220 jetting...am I on the right track

[Headset]

I have a 220 with all the standard mods (FMF rev pipe/silencer, airbox lid removed, boyseen reeds, running Golden Spectro @ 50:1)
I just moved from Virginia (Sea Level) to New Mexico (altitude 5k-6K)
Back East the bike ran great with stock jetting
Out here in NM at the higher elevation, it runs like crap on the top end. It pulls pretty good off the bottom but then it falls apart on the top...kind of sputters.
Am I on the right track by going from stock jetting to a 142 main and a 40 pilot?

 

[Green Hornet]

Got Bigger Jets
go to http://www.dirtrider.net/justkdx/carbtuning.html

 

[razrbakcrzy]

Try this example:

Example- I’m presently running a 45 pilot jet with the air screw 1.25 turns out, an 1173 jet needle in the second from the top clip position and a 152 main jet. This jetting was optimized at 20° C and 2240 ft above sea level. For this example lets assume I’m going riding in the mountains where the temperature is 20° C at 9600 ft. The first thing I do is adjust the bottom of the table so that it reflects the condition where my jetting was optimized. Using the illustration below as an example I draw a straight line from 20° C horizontally across the graph until I hit the line that represents 2240 ft., then draw a line vertically to the bottom axis on the graph. This point becomes 1.0. Adjust the work sheet by subtracting 0.02 for each increment to the left of this point and adding 0.02 for each increment to the right of this point. My graph now looks like this:



Now using my personalized graph I can calculate what jetting I should install before making the trip to the mountains. I draw a horizontal line from 20° C over to 10000 ft and then vertically down to determine the correction factor of 0.95. To find the correct pilot jet size I multiply 45 by 0.95 and the new jet size would be 42.75. The closest available size is a 42 and I’ll fine-tune the pilot circuit with the air screw once I get there. I then multiply my main jet size ,152, by 0.95 and the new jet size would be 145. Now remember this is intended to give you a rough indication.

Using a correction table should allow you to closely meet the requirements of changing conditions. It is however intended to be used as a guide. You should always carry an assortment of jetting in your toolbox and check any jetting suggestions you receive. At a minimum do a plug reading at WOT after changing your jetting to insure you aren’t running lean. Jetting recommendations that work well for one bike may not necessarily work for another even if it is being ridden in the same area with identical modifications.

The graph he is refering to is on the page the previous link will take you to.

 

[Green Hornet]

Razor-Thank God for Cut n Paste, Ehh

 

[razrbakcrzy]

yes sir!