high altitude menace

[sausage boy]

? hey,

is anyone out there experiencing problems riding above 9,000ft? i have an 05 WR450 165 main red needle #4 factory pilot and leak air screw 1 1/2 turns out. when i ride up moderately steep trails powering up in 3rd after a shot while it starts to pink and mis-fire like its running to weak or over heating. i'm worried its going to lock up. any ideas ?

[Indy_WR450]

160 Main, JD rd #4 , 45 pilot, 1.25 turns out should be fine at 70 degrees at 10,000 feet. ? Try some fresh fuel and put in a new spark plug as well. ?

[sausage boy]

hey Indy you seam to be the jetting guru ? i have removed the AIS would that make any difference? also what heat range plug?

thanks ?

[skidxr]

I just did a ride on Sunday with my 05 WR450... Elevation ranged from 6,500ft up to 11,522ft... The WR performed perfect.. I was very impressed.. I have the stock jetting,, don't even know what the numbers are.. The airbox snorkel out and the exhaust plug. Also removed AIS,,, poping on decel gone now.. The ride was 178 miles and the WR just kicked ass..

[ashakin]

My friend and I went riding last Saturday. I have a WR450F, he has a YZ 450F. We both experienced the same problem(Sputtering, missing, etc) as described in the beginning of this thread at exactly the same altitude. I suspected that it was overheating but noticed that there was fuel pouring out the overflow tube. It seemed like my float valve was stuck.

I tried it twice, I went back down and it stopped leaking at around 8000 feet. I went back up and it started leaking again. I ended up turning off the fuel valve and just turning it on for a count of 5 every minute or so(manual float valve). This worked fine except when the carb ran out of fuel in the middle of a tricky hill climb.

I would have thought it was just my bike, but my friends did exactly the same thing(both times). The carbs are almost identical between the two bikes...Strange, I can't understand what altitude would have to do with the float valve.

[sausage boy]

My friend and I went riding last Saturday. I have a WR450F, he has a YZ 450F. We both experienced the same problem(Sputtering, missing, etc) as described in the beginning of this thread at exactly the same altitude. I suspected that it was overheating but noticed that there was fuel pouring out the overflow tube. It seemed like my float valve was stuck.

I tried it twice, I went back down and it stopped leaking at around 8000 feet. I went back up and it started leaking again. I ended up turning off the fuel valve and just turning it on for a count of 5 every minute or so(manual float valve). This worked fine except when the carb ran out of fuel in the middle of a tricky hill climb.

I would have thought it was just my bike, but my friends did exactly the same thing(both times). The carbs are almost identical between the two bikes...Strange, I can't understand what altitude would have to do with the float valve.

where were you riding? maybe it was some weired shit going on ? what jetting are you running?

[Indy_WR450]

hey Indy you seam to be the jetting guru ? i have removed the AIS would that make any difference? also what heat range plug?

thanks ?

Stock heat range plug. BR8ES or BR8EIX

AIS removal is good for your jetting.

[sausage boy]

thanks all who replied

[Dan_Lorenze]

I just did a ride on Sunday with my 05 WR450... Elevation ranged from 6,500ft up to 11,522ft... The WR performed perfect.. I was very impressed.. I have the stock jetting,, don't even know what the numbers are.. The airbox snorkel out and the exhaust plug. Also removed AIS,,, poping on decel gone now.. The ride was 178 miles and the WR just kicked ass..

I would really be interested in the Jets... "Stock" is subjective.. Your dealer could've jetted your bike... If your bike runs great at that altitude I'd love to see the numbers... My bike will be in Colorado in August....

[story_rtw]

Last weekend I was riding here in Colorado at elevations between 8k-10k and my '05 WR ran perfectly. Here's my setup/jetting:

airbox snorkle removed

gray wire snipped

YZ throttle stop screw

AIS removed

stock muffler, small baffle removed

Zip Ty fuel screw 1.75

160 main

45 pilot

JD red needle #3

Might be a good starting point for your Colorado riding.

Dan, you said you'd be riding here in August. Does that mean I'll see you at the Colorado 500? We need more blue bikes to balance all the orange ?

Story

[Dan_Lorenze]

Dan, you said you'd be riding here in August. Does that mean I'll see you at the Colorado 500? We need more blue bikes to balance all the orange

Story

Do doubt!! ?

Actually, I'm letting my father borrow my bike, he's an excellent rider that's owned a few WRs. He was about to buy an 05 but I told him to wait for the 06's and borrow my bike for Colorado, he took the bait, he'll be on my bike... I have a heavy work load for August. I think it's the Colorado 1000, it's the one that Jerry Epperson organizes. Thanks for posting your jetting story, Story ( ), I'll jet it like your bike except I'll have the WR needle instead of the JD red... I'll install my Powernow just to give the old man some punch on the bottom. ?

Thanks for your reply....

Dan

[ashakin]

My friend figured it out. It was HOT and high up. We were climbing pretty fast. The pressure in the tank was building up faster than it could escape via the fuel vent(seems to be close to a one way valve) so it was forcing the fuel into the carb. The float valve couldn't close due to the pressure and the fuel poured out the overflow.