XR 650L High Altitude Jetting


11 replies to this topic
  • tputnam

Posted April 02, 2008 - 06:17 PM

#1

I have a '03 650L that I will be taking up to Colorado this summer, riding between 8000-12000ft. Everything is bone stock right now, I ride at about 800ft. right now and everything works good now. What will I need to do to keep it running up there. I'm not looking for any high performance mods, just going to be doing some fire road/trail riding. Any help will be appreciated.
Thanks,

Thad

  • riding4life162

Posted April 02, 2008 - 07:28 PM

#2

I am no expert in carb work but I asked a similar question bout 2 days ago, because I am moving in a few days to utah, where the elevation is between 5000 and 10000 and he told me 155/52 f i had the daves mod.

  • RipperFox

Posted April 02, 2008 - 08:05 PM

#3

Keep in mind you are already lean with the stock jets. Then apply the following guide

http://www.4strokes....ch/howtojet.asp

Well written.

And dont forget...Gas is different at high elevations.

  • Denn10

Posted April 02, 2008 - 08:08 PM

#4

I am no expert in carb work but I asked a similar question bout 2 days ago, because I am moving in a few days to utah, where the elevation is between 5000 and 10000 and he told me 155/52 f i had the daves mod.


for8K and up you will prolly want even leaner than this, 50 pilot and 152 main will prolly be closer to the range you need for that high of elevation. but for 8K 155/52 would be good, so if you just wanna use that and run rich above 10k then thats your choice. Dont know how long youll be at the elevations, so alot depends on where most of your riding will be

  • martinfan30

Posted April 02, 2008 - 08:30 PM

#5

Ive ran 158/55 all the way up to 10,500 ft. Didnt run great, but it still ran ok. Very rich. Just keep a few jets in your bag to change out when you get real high up.

  • XR650L_Dave

Posted April 03, 2008 - 08:27 AM

#6

Stock jetting might be just fine for 8Kft. Try just drilling the slide and shimming the needle, and the foam filter and snorkel removal.


Dave

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  • cleonard

Posted April 03, 2008 - 09:08 AM

#7

Up to 10,000 you should be OK with what you got, at 12,000 you might need a little adjustment. The air pressure is down to about 60% of sea level. Even with proper jetting the power will be down by that amount.

Another thing to consider is how you are going to react to 12,000 feet.

Consider 152/52 or even 150.

  • cornelieaz

Posted April 03, 2008 - 02:31 PM

#8

I live at 7000ft. Bike runs great with stock setup. Perfect fix for all the lean stock jetting I always hear about.

  • glin60

Posted August 12, 2008 - 07:51 AM

#9

Seems like there's a wide bunch of opinions on this. I'm getting ready to do dave's mods, and realistically 80% of the riding I do is between 4000-6000 feet, occasionally going higher than that if that particular trail goes that way. Martinfan, you seem to want to go with the perscribed 55/158 at that elevation. Would the potential addition of an FMF pipe solidify that richer jetting? Thanks for your input guys, TT should pay you for this!

  • martinfan30

Posted August 12, 2008 - 08:00 AM

#10

Seems like there's a wide bunch of opinions on this. I'm getting ready to do dave's mods, and realistically 80% of the riding I do is between 4000-6000 feet, occasionally going higher than that if that particular trail goes that way. Martinfan, you seem to want to go with the perscribed 55/158 at that elevation. Would the potential addition of an FMF pipe solidify that richer jetting? Thanks for your input guys, TT should pay you for this!


I think so. Any higher, I'd drop to a 155/52. Or real high, 152/50.

  • motobikem1ke

Posted August 12, 2008 - 08:20 AM

#11

We trail ride Mount Kiliminjaro regularly and frequent Everest and K2 as part of our "Xr's for Sherpas" non-profit organization, and I prefer to go WAY leaner on the jetting at really really really really really high altitudes.

We go with a 25 main and a 4 on the pilot when we ride above 19,000 feet. When we are summiting Everest, we usually just stick bubble gum or an international flag in the carburetors to lean the jetting out completely.

  • Itchykawa

Posted August 12, 2008 - 04:00 PM

#12

I did a ride through Colorado and other western states on my 650L from 3 to 14 thousand feet. Bike is desmogged, desnorkled, has a K&N filter, Dave's Mods (55/158), the fuel/air screw is at 2 1/2 turns from lightly seated, and has the stock exhaust with the baffle removed and replaced with something that flows better (my own budget exhaust mod).

It lost some power in the higher elevations but, being a 650, it still had plenty left and this wasn't a problem AT ALL. It otherwise ran great and even had plenty of power left for some gnarly hillclimbs at 12,000 feet - no sputtering or missing at all. No fouled plugs either, though I wouldn't risk this trip without some. The ONLY adjustments I had to make were to the idle screw at different altitudes - simple adjustments that didn't even require me to step off the bike. The higher I went, the lower she idled.

Unless your bike is some kind of pure hotrod with cams, high compression piston, pumper carb, and the likes I wouldn't worry at all. Get familiar with the idle screw, (it's under the left side of the seat), practice adjusting it while sitting on the bike. To do this, your thumb goes OVER the fuel line and your index finger under it. Clockwise for more RPM and counterclockwise for less. AND HAVE FUN!

PS... I know this thread is old but figured others might want to know this. :)





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