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jetting for trip to CO

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I searched but there is almost verging on too much jetting info in here, it gets quickly overwhelming, either that or I just suck at searching.

Anyway, currently at about 600 feet in average 90° daily highs (though the bike runs best in the 70s) and high humidity.

2008 DRZ400SM

stock exhaust w/ endcap drilled out (spark arrester still in place)

3x3 w/ JD kit, 155 main, 4th clip on the blue

currently 25 pilot with extended screw but will soon change back to 22.5 per Eddie's recommendation..after I finish getting my wife's KLR ready.

Will be spending 3 days riding at 9,000 to 12,500ft in southwest Colorado, average daily highs in the low 70s, lows in the 30s.

I could swear I read a "rule of thumb" on jet sizes per thousand feet of altitude or something, but can't remember or find it now. Don't know how accurate it really is anyway. But since we have a limited time to ride I'd like to start off as close as possible without having to spend a day tuning.

I will also have a bone stock KLR250 and a Honda TRX400EX quad w/ FMF powercore4 with us that we'll have to get tuned. The KLR is my wifes and I dont remember what was in it, but am 98% sure it's stock. CVK34 carb. The guy with the Honda quad is planning on putting the stock main jet back in, whatever it was before the exhaust. Is the difference in 9,000 feet of altitude roughly the same as the difference of stock exhaust vs aftermarket?

Any pointers that will save us some time? Unfortunately the only specs I know exactly are my own DRZ, but like I mentioned before is there a rule of thumb that might help us out for the rest of the stuff? I figure if Eddie can hit my jetting spot on like he did at 600 feet I trust him at 10k feet as well.

Thanks in advance...

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12% less than 155 is...136.4, so a 135? Good thing I posted this thread when I did, because I don't think I have any smaller than the stock 142.5.

Red needle is no problem....

Thanks, Eddie!

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so is it like a 1% per 1,000 feet of altitude?

I didn't want to start another thread on this...but what is going to happen to my fuel economy with this? We're doing the alpine loop starting at lake city, out to animas forks via engineer, california and corkscrew gulch out to the highway, double back and then cinnamon pass back to lake city. I think the total will probably be about 75 miles and I usually hit reserve at 90 on easy street riding. If I need to I can go into town and get gas in Ouray while we're relatively close but it'd be nice if we could do the whole loop on just our tanks and the 5 gallon gas can we'll have on the back of one of the quads.

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we did a little internet research and the owner of the Honda 400EX found a website that recommended a 170 main jet with his mods (a FMF powercore4 slipon). So he ordered a 150 for Colorado. Tonight we went to put it in and found a 155 in there. He then told me it hadn't run real well since he bought it a few months ago (and hasn't ridden, since he also has a 450R), and that it runs better partial throttle with the airbox lid off, but feels flat on top, like he's rich in the pilot circuit and/or needle but lean on the main. I told him he shouldn't try to jet for Colorado based on his jetting here if it's not even right to start with. It was getting dark and the mosquitoes were out in force so we didn't have time to put it back together and do a pilot circuit test. We also didn't take off the bowl and see what the pilot jet is, it's got a plug in the bottom that uncovers the main jet, but not the pilot.

It's a Keihin of some sort, not a CVK or a FCR. It has a butterfly and a slide that open in unison with the throttle cable (not a vacuum slide).

Also...we noticed that the jets for my Mikuni and his Keihin look identical. Are these things interchangeable between Mikuni and Keihin?

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re-jetted yesterday...is it normal that all the paint from the top of the needle is now gone? There's just a slight hint of blue over on the edge of the top...if my red needle comes out that way when I swap back next week I'll have to be real careful not to get them mixed up!

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