Alright you Colorado guys what is the main jet size you use when going over 10 thousand to 14 thousand feet. Will the stock jet do? Thanks for your input

 

Are you talking a stock bike? I believe Bill Blue recomends 10% leaner on the main, thats all. I tried it (10% smaller main (on a stock bike) a couple years ago near Rocky Mountain Natl Park (8600' to 11,000' ) I couldn't get the thing to run right with the smaller jets. I will say I'm sure this was all due to my total lack of experience tuning carbs. What I finally did to get it run decently was to simply remove the air box lid. That was enough of an increase in the air fuel ratio to let her run ok. It still bogged a bit at full throttle but for the time I was there it was close enough.
I'm going back out to CO. soon and this time I have the 351 and a aftermarket exhaust, so I have to start all over. I'm interested to see any colorado riders responses. I know I'll go with an adjustable A/F screw and some smaller main jets.
Dan

 

It's still snowing in the high country so I've only been up to 7000 ft. so far. My bike currently has:

HMF exhaust with quiet core and spark arrester
stock air filter
snorkel removed
backfire screen still in place

With that, I'm running:

125 main
stock needle shimmed with .025" brass washer
38 pilot
Kouba fuel screw, 1.5 turns out

You'll need to go leaner from where you are now across the entire range, not just the main jet. At a guess, I'd say you'll need a couple of sizes down on the main, lower the needle one notch, maybe one size leaner on pilot and play with fuel screw position. Kouba screw would be a good idea.

Maybe someone else can chime in with their experience...

Debby

 

Often with the closed throttle idle mixture you end up going richer. The thin air doesn't pick up as much fuel as it passes though, has more effect than the lack of o2 in the air.
what you'll usually notice is the idle gets lower and lower as you go up, till at some point it stalls when you stop. Then you reach down and turn the idle speed up and all is fine again. Then at some point you notice more closed throttle deceleration popping, which you either ignore, roll the throttle off slower, or get off and adjust your fuel screw.

Different with the mainjet at wideopen throttle lots or airflow, the lack of o2 is predominant. So you go leaner, or just live with the lower mpg. At some point it starts to blubber real bad and won't take full throttle you either rejet, pull the airbox lid, uncork the pipe, find some oxygenated fuel or some combination of all. Or you just finish the ride off the mainjet, knowing that what goes up must come down and it'll be fine again on the other side of the pass.

The needle or the partial throttle positions, have your right wrist and the diaphragm effect of the vacuum slide to somewhat compensate, so you usually get by without much problem there.

Luckily the klx isn't too hard to rejet on the road, now my full faired 4 cyl bikes? I just suffered the altitude sickness and plowed on.

 

I have the dyno kit and have not installed it because I will be going to Colorado in August. The bike runs ok for now, starts easy and runs ok but it definitely needs to be jetted. I was hoping on leaving the stock kit in but it looks like I am going to just go ahead and do the jetting twice. This sucks because the carb is a pain to take off. I guess I will get better at this with practice.

 

You can rotate the bottom of the carb to the pipe side and change jets, and get to the needle from the top. No need to pull carb. I pull the hoses and throttle cables to make it easier.

When the bowl is off take the 4 screws to the screw store and replace them with socket head screws, and pick up a ball head allen wrench that size. The future jet changes will be cake.

 

I was in Moab earlier this month, and I got to 10,000 feet on a couple of runs over the La Sals. My '06 ran surprisingly well with its 1700 foot altitude jetting from here at home. It has a Kaw 300 cylinder, DJ128 main, DJ needle in 3rd groove, 35 pilot, Kouba fuel screw, open airbox, and full Muzzy exhaust. Idle slowed a bit, but I didn't even have to adjust it or the fuel screw. Frankly I was surprised. I'll go to the Silverton/Ouray area in Colorado as usual in August, and I'm not going to change anything. I'm sure it will chug a bit as I summit Imogene Pass at 13,000 just like my KLR650 did, but I think it will be fine for 95% of the riding there. These CV carbs have a decent fudge factor at altitude unless you're already on the rich side.

 

+1 Easier to spin the carb in the boots, and rejett. I replaced my bowl screws before heading out west last time. The Allen head bolts won't cam out like the stock Phillips heads will. I replaced the screw that holds the throttle cables on with an Allen head too. Definitely makes things easier.

Thanks for the replies, Sounds backwards to richen the idle, but makes sense the way you explained it. I don't have the Kouba screw but am ordering one asap.
Dan

 

I live at 7000 ft and I've settled on a 125 main and a 35 pilot. Screw is 2.5 turns out. I have an adjustable needle and the clip is on the top groove, the leanest position. it's running really good. If you plan to spend all your time higher than 10K ft. then maybe a 122 main would be be the way to go.