85 500 Xc jetting

Anyone know the factory jet specs? Also anyone have suggestions for jetting at around 4500ft elevation? It's got the 40 mm mikuni on it. Pretty much stock besides dynoport pipe. As of now it's running pretty rich. I use castor 927 at 50:1 in all bikes on 91 oct.

Much appreciated!

I am running an 85 motor and my riding area is from 3000-3800 feet. The following works well for me but my riding style is definitely not flat out and on it...all the time. It is conservative riding for a 73 year old. Motor runs clean and pulls hard without hesitation....decent starter...most of the time!

Mikuni 40mm
Main jet: 350
Needle jet: AA2
Idle Jet: 35
Needle Pos: three from the top
Air Jet: 0.7
Needle 7DH3
Slide 2.5
Air Screw 1.5 turns from the bottom.

Running Maxima @ 40:1 on 91 Octane. I could probably run the motor a little leaner but why take the chance and lean it to far....!

Hope this helps.

The weather conditions are a big factor to consider, not just elevation. For example where I am going riding today here in the north eastern part of Oregon the elevation will be 3400-3700 ft. But when I factor in the temperature barometric pressure and humidity I get a corrected altitude/density altitude of 1171 ft below sea level. Depending on the time of the year, where I ride and weather the Main jet size on my 420 auto will be anywhere from a #370 to #430. Also make changes to the needle clip position if needed.

Marty

I'll probably jet it for our summer weather as this one isn't going to see much winter weather. We see such a huge range in temps here that it would take to much time to re-jet all of them and I pretty much only put my 15te300 through the crap winters we get here. To much work into the old ones to abuse them. I take them out once or twice a month during summer/fall then they stay in the garage through the cold months. Thanks for all the input!

I was told to jet it correctly to your mix ratio. Then in the fall go up one number rich on the pilot if the balance screw isn't within 1 1/2" turns out. And raise the needle up one clip for winter riding. It depends on where we live too.

I been thinking, (maybe too much free time here) once you nailed down the jetting for summer why not change you mix ratio for the winter. You can richen the mix ratio (gas wise).

Years ago when the snow came we had an old drive in to ride in. The ice screws went in and we were the only ones there. Of course someone sued during the summer and we lost that place.

you may have been told about the "oil ratio jetting" somewhere else, but here many will tell you its a waste of time. we have before.