New exhaust, jetting question in Colorado

[dlee]

I ordered a new big gun slip on pipe the other day for my 06 XR650L, I was wondering if anyone knows what jets I will need at 5500- 9000 feet in Colorado, also how many turns on air/ fuel and possibly needle position

 

Thanks

Edited April 7, 2017 by dlee

[ScottRNelson]

Assuming you've also opened up the airbox, a 152 or 155 main jet is what you'll want.  You'll have to check for yourself on the mixture screw, but it should be between 2.0 and 2.5 turns out.  There are several posts here about how to set it.  I've read them, but never bothered to actually do it, since I'm happy with how my bike runs currently at 2.5 turns out.  As for the needle, you'll probably want to leave it in the original position rather than shimming it to make the midrange a bit richer.

[dlee]

Do you have a Big gun exhaust on your bike? Did you have to re jet yours?

[ScottRNelson]

10 minutes ago, dlee said:

Do you have a Big gun exhaust on your bike? Did you have to re jet yours?

The brand of exhaust on an XR650L doesn't have all that big of effect on correct jetting for the bike.  I'm pretty sure that I could swap on the top ten most favorite pipes and my bike would run just fine with all of them.  Besides, in my experience, what you do to the intake has a bigger effect on the jetting than what you do to the exhaust.

When I bought my XR650L, it already had a White Brothers exhaust on it and a modified airbox.  It ran pretty well, but I pulled all of the jets out and put new ones in there just to be sure of what it had.  I swapped on a SuperTrapp muffler for a while, in hopes of reducing the noise it produced, but went back to the White Brothers because I could tell a slight difference in power and it didn't improve noise at lower speeds where it mattered most to me.  I didn't feel the need to do anything with the jetting during that switch.

Stick your new pipe on there, put a 155 main jet in it, then see how it runs.  If you feel that it's rich, swap down to a 152.  You can separately figure out if the midrange is okay or not and then consider fiddling with the metering needle.  Find the post on adjusting the idle mixture screw and do that.  Then go ride the bike and enjoy it.

[dlee]

Thanks, I will give it a go!

[dlee]

I put on the new pipe tonight, it was back firing and poping pretty good, I pulled the carb to see what size main jet is in there, to my surprise I had a 142 main jet. In my manual it calls out for a 150 main at or above 6500 ft. Do you think i will need to change the pilot jet?