From Low To High Elevation

[Arkterra]

Hi all, I live in Nebraska and am pondering taking a trip to Colorado. My ST1100 works great at my home elevation (1100ft) but for a quick trip to higher elevations (some passes at 10,000ft) do I need to be concerned? I know the engine creates less power at elevation, but I'm more concerned with the fact it is carborated and possibly won't run correctly. Any advice or personal experiences would be greatly appreciated. Thanks!

 

[Uncle Phil]

I never had any trouble with any of my ST1100s except when I rode up Pikes Peak.

Uncle Phil - Highway 50 2017 Day 07

Monarch Pass at 11,000+ was fine on the same ST1100.

I've ran all the Sierra Passes in one day with no problem -

Uncle Phil - West 2007 Day 04

12,000 feet or below you should be fine.
Above that you may have issues depending on your ST1100.

 

[Al st1100]

Mine is a dog over 10,000 ft

 

[red one]

The Owners manual says some High altitude adjustment may be required. But I would listen to the ones here that know such as Phil and others.

 

[paulcb]

Mine is a dog over 10,000 ft

Mine is too. I've ridden many times over 10k ft., no problems. I've gone to 14k (Mt. Evans), still no issues, just low power and rough idle. I bump my idle up when I get over 8k ft. or so. Remember to give extra time when passing.

 

[John OoSTerhuis]

BTDT You may be down a bit on power above 10K’… downshift if necessary. Not to worry.

BTW, there is a carb procedure in the Honda Service Manual if you live and ride above 5K’. Edit: continuous operation above 6,500 ft per the Service Manual… basically just turn the pilot screws 1/2 turn CW with the Honda special tool.] Not worth the effort if you’re just passing through.

BTW2, make sure the little vent holes in the back side of the panniers are not plugged before venturing on up to altitude.

BTW3, if the gas stations at higher elevations have 85 octane, use it.

John

 

[sherob]

Plenty of higher octane fuel here... even Murphy's has "real" 87.

Oh, and enjoy your trip! I live off of 76, if you're riding down it. Ping me with your details when you decide to ride down and I'll buy you lunch at a hole in a wall burger place.

 

[oude geit]

Should not be a problem. loss of air pressure also means less air pressure pushing fuel in to engine. My 1300 prefers 87 oct at elevation...

 

[Al st1100]

Should not be a problem. loss of air pressure also means less air pressure pushing fuel in to engine. My 1300 prefers 87 oct at elevation...

Fuel injected vs carburetor = big difference .

 

[sherob]

Fuel injected vs carburetor = big difference .

One reason I went on a strict carb diet.

 

[mudduc]

This re-awakened my curiosity on why do we get better mileage when riding at high altitudes. Not to hijack this thread, I opened another over here: Better Mileage at Altitude

Come help me figure out why, if you feel like it.

Later,
Kent Larson in Minnesota

 

[Arkterra]

Thanks all! I've been to high elevations many times but never on a carborated machine. Looking forward to it!

 

[oude geit]

Ive not noticed any real difference between carbs and injection myself. My vtx performs just as well as the st.

 

[DeanR]

I noticed no problem on Pike's Peak, Rocky Mt Nat Park, Beartooth with either of my 1100's.

 

[tmoldovan]

Hello fellow Nebraskan, I don‘t know about carb adjustments, but I think you will want to make sure the highest octane fuel you can get.

 

[Uncle Phil]

I noticed no problem on Pike's Peak, Rocky Mt Nat Park, Beartooth with either of my 1100's.

I think it depends on the ST1100.
What is interesting is the one I had trouble with is the only one that has the pair system removed (before I got it).

 

[TipSTer]

Perhap adjusting your mixer screw on carburetor. Prime gas help too.

 

[Chris09]

my two cents before I do some research and get it right, but if I seem to recollect correctly on the operation of the basic CV is that it's more of a mass flow rate type of mechanism; thinner air has less mass and results in lower CV thingamabob aperture [I like that word, if no one says anything... it's gonna get used more] position and being connected directly to the whwowhwo [tappered rod in the main jet.. it's been a while, and a few brain cells] it tends to compensate for air density and maintain a fairly constant air / fuel ratio. Anyways, something along those lines, I know they don't use too many Rochester Quadrajets on them. I did look a bit on the specific differences and all going on with the CVs but I guess it's going the way of the doo doo, I've got a twin CVd with only 3k, at sea level here it's I wonder if I ever drove it in Calgary for example [3,450] if I might want to change the jetting; also maybe getting a bit off but I noticed during my time of advancing the odometer on said carbed machine from the 3 to 5k kilometer mark I think I'm solely responsible for the slight bluing of the pipe inlets, wondering if my using the 94 affects that. But a good link to the CV explained would be relative to this discussion, will post if I find.

 

[John OoSTerhuis]

Not to put too fine a point on it, but as designed 32+ years ago, the ST1100 carbureted engine does not require, nor does it benefit from, higher-rated-than-spec’d octane fuels, including at altitude. 85 octane fuel was formulated for carbureted engines at altitude and is fine in our ST1100s, we don’t need more of the anti-detonation additives in the higher rated octanes retarding combustion in our engines. Plenty of references available on this issue.

Caveat: bump up a grade if you do experience detonation/pinging and do a carb tune as soon as you can.

Running 85 at altitude should give you higher MPG than 87 does at sea level.

N.B. Words like “premium” and “high test” etc. do not mean better. ”Treating” your ST1100 to “the good stuff” is just a waste of money, IMNSHO. FWIW

Edit: the High Altitude Adjustment procedure for continuous operation above 6,500 feet is on page 5-16 in the Honda Service Manual. Basically turning the Pilot Screws in CW 1/2 turn with the appropriate Honda Special Tool (USA or Canadian version).

John

 

[Al st1100]

Hello fellow Nebraskan, I don‘t know about carb adjustments, but I think you will want to make sure the highest octane fuel you can get.

not.. it's the exact opposite of what you want to do