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Discussion Starter #1
Hey folks, we have grown kids and a grand child in Alma, CO and also Leadville, CO. Both towns are above 10,000 ft. Our cars/trucks that are not turbo charged have a significant reduction in HP at those altitudes. We have not had our, new to us, '98 GW 1500 up there yet. Does anyone have experience with this elevation and how did your bike perform?
Thanks, Mark
Green Bay, WI
 

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Where your 1500 is carbureted, you will see some drop off in performance as you gain altitude. I run an 1800, which being fuel injected, fares a little better, but will lag a little at those altitudes. You may have to adjust how much choke you use when starting up. I would guess your fuel mileage will suffer as well, so make the most of your stops and top off when you can. Beyond that, have a safe trip.
 

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I never noticed any problems with my 1500 when at higher elevations.
 

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I spent some of my early years growing up in Colorado and remember my dad making adjustments to the carburetors on our vehicles when going into the mountains.
 

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Discussion Starter #5
Thanks for the feedback. This is the formula we use for a carbed snowmobile. HP Loss = {(elevation x 0.03 x horsepower @ sea level)/1000}. A carbed motorcycle in Alma would lose: {10,578' x 0.03 x 100HP / 1000} = 31.7%. Changing the carb jets brought back some of the loss. I am just curious about real life stories about hauling 400# of cargo on a Wing up the grades.
 

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Several years ago i ran a 1500 Valkyrie (six carbs) over many 10-11,000 ft passes. I was solo
but loaded down with gear (month long trip). I agree with Riders numbers - felt like I lost 25-30%
power, but still plenty left. Just made sure I had lots of room to pass the struggling RVs.
On the other hand, a very LARGE couple riding a Valk trike (250-300 lbs heavier) was down to second gear for the last 1000 ft of elevation.The trike and riders outweighed me by 550-600 lbs and still had plenty of torque to get the job done.
I wouldn't worry about adjusting carbs - just give yourself lots of time and enjoy!
 

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Discussion Starter #7
Several years ago i ran a 1500 Valkyrie (six carbs) over many 10-11,000 ft passes. I was solo
but loaded down with gear (month long trip). I agree with Riders numbers - felt like I lost 25-30%
power, but still plenty left. Just made sure I had lots of room to pass the struggling RVs.
On the other hand, a very LARGE couple riding a Valk trike (250-300 lbs heavier) was down to second gear for the last 1000 ft of elevation.The trike and riders outweighed me by 550-600 lbs and still had plenty of torque to get the job done.
I wouldn't worry about adjusting carbs - just give yourself lots of time and enjoy!
Hey Slowpoke, Thanks. That is exactly what I was looking for. We ride 2-up at 350# plus some luggage, so I'm guessing we are nearing 400# total. It sounds like we should be okay.
 
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Hey folks, we have grown kids and a grand child in Alma, CO and also Leadville, CO. Both towns are above 10,000 ft. Our cars/trucks that are not turbo charged have a significant reduction in HP at those altitudes. We have not had our, new to us, '98 GW 1500 up there yet. Does anyone have experience with this elevation and how did your bike perform?
Thanks, Mark
Green Bay, WI
I ride the Rockies regularly, going over all the mountain passes on 285, 160, 50 and 70. But, I have a 2012 that is injected. However, when I rode them with my 1985 Aspencade, though I noticed some drop in power, the engine is still larger than some of the smallest automobiles out there. Just adjust your estimation of power to speed ability when passing and don't mess with the carbs. You will be fine. Keep the shiny side up.
 

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I have never owned a GL1500 but they are equipped with CV carburetors. My previous bike was a Kawasaki Voyager 1200 which also has CV carbs and I rode that over the Beartooth Pass and the Big Horn mountains with no problems. The bike ran just fine, may of had some power loss a the very high altitudes but not significant.
I would not be concerned with anticipating any real problems.

EDIT: Forgot to mention that I was pulling a 375lb trailer behind the Voyager, and it did much better at altitude than my buddy's Harley Tri-Glide also pulling a trailer.

Found this:
"a CV carb by design can compensate for differences in atmospheric pressure. it has a vacuum chamber which measures/responds to engine vacuum, another chamber sealed off from vacuum chamber which is open to atmospheric. there is also a spring for the vacuum source to overcome.. if there is less atmospheric pressure (read Hi Altitude) there is not as much vacuum therefore the ability of the vacuum chamber to pull up the slide is reduced in effect limiting the amount of fuel introduced into the combustion chambers." quoted from a different forum.
 

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Discussion Starter #10
823 Thanks for posting the quote. This helps me to better understand how Honda managed atmospheric pressure variances.
 
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