XR 400 high altitude riding

CAB

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#1
Getting ready for a trip to Taylor Park, Colo. A friend is bringing a 2000 XR400 and XR200, bone stock. Does anyone know if they can get away with stock jetting. They normally ride at about 1000 ft (San Antonio). I know my DRZ400E (stock) runs fine up to about 13200 ft, but I'm not sure about the XR.

Any experience or advice?
 

Rodzilla

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#2
Cab,

Stock shouldn't be a problem, you say stock does that mean the snorkle is in?

I'll assume it's out. I'm running a 142 main on my '00 but for a vacation trip the XR should run O.K. stock jetting

I don't remember which pilot I'm running but I'll look tonight.

Rod in Denver

p.s. Taylor Park rocks!

Serious singletrack!
 
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mtngoat

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#3
Some of my family and friends bring their XR4s with stock jetting (good for sea level) up from the valley. Bikes run rich, but run OK at 7000'.

For 7000' riding, with no snorkel, K&N and a pipe, I'm running a 155 main, 55 pilot and a dual-taper needle in the middle position. Works well up to 10,000'.

I tried a 145 and didn't notice any "popping" at high RPM, but I think I was running very high head temps, since I noticed my head gasket "seeping", which went away when I jetted richer.

I used the correction factors from the manual to arrive at my current jetting. I know "leaner is meaner", but the XR doesn't seem to exhibit "tell-tale" lean pops/hesitation when jetted too lean, like I've experienced on too lean DRs.
 
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#4
Not just jetting.

If you are going to be riding that 400 on gnarly mountain trails, I'd suggest going one tooth smaller than stock on your countershaft sprocket. You'll be glad you did when the trail turns steep, tight, and rocky. I changed mine and it was the best mod I've made. Didn't even need to shorten the chain as the adjusters had enough travel to take up the slack.

Sorry I can't help with the jetting. I have it all written down, but it's at home. Mine has the snorkel removed, uni filter, and a Baja baffle. I had to go to what seemed very rich on the slo jet to get rid of the off idle hesitation. If this thread is still going this evening I'll chime in with my jetting for 5000-9000 ft.
 
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#5
I just came back from the Salida & Poncha springs area, I was riding between 6000' and 10'000 ft. 98 XR400 no snorkel , 152 main
 
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#6
Here's what I'm running in my '00 XR400 (Uni filter, snorkel off, baja baffle with '97XR400spark arrestor) for 5000' to probably 9000':

152 main jet
62 slo jet
Needle clip 2nd groove (from top)

Also, I highly recommend a 14T counter shaft sprocket.
 

fremontguy

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#7
One of the nice things about xr400 is once I dialed in the jetting-(4 tries), I haven't messed with it in a year and no fouled plugs like 2 stroke :) Currently run 58P, 158M, dual taper stock needle#2, snorkle out, Al Baker pipe, K&N, good up to 6k'+. VintageDirt,(VD?) does the 62 pilot elliminate throttle hesitation? I have noticed this problem the most in cold weather, so I assume lean down low. Stock 142 main sounds a little lean, might work though.
 
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#8
Originally posted by fremontguy
VintageDirt,(VD?) does the 62 pilot elliminate throttle hesitation
Doesn't eliminate it, but with the lower gearing and the 62 pilot, I barely notice it.
 
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#9
My '00XR4 has Gordon mods, snorkle removed, UNI filter. I run 155/55 here at home at 3600ft.. When I go to the mountains I jet it to 150/50 and drop the needle 1 position. I agree with the others about dropping the front sprocket to a 14. It will make a world of difference on knarlly mountain trails and will also help make up for poor jetting if you don't get it dialed in just right. Don't forget to readjust the fuel screw for best response once you're up there.
Derek