The times I've been up to 14,000 ft, my ST1100's have not missed a beat (87). Never really noticed a change.
Sure noticed it when walking slightly uphill though!
Sure noticed it when walking slightly uphill though!
Correction for that assumption, pistons are drawing SAME amout of air in cyls., just not as much OXYGEN content in what's being drawn in My normal riding elev. is 5,000ft., and everything goes UP from here in three out of four directions to over 10,000ft. elev. when traveling those three directions some 40-80mi. Cyl. compression or pressures has to do with compression ratios, NEVER altitude changes.Here's what I found on using lower octane at higher altitudes:
"Air is thinner the higher above sea level you go. Less air going into the cylinders means less pressure at top dead center when things go bang. It's a lot like lowering the compression ratio in the engine, reducing the need for high octane. Cars will run just fine on lower-octane fuel when they're well above sea level-"
Ray
Only change that is obvious is the 3% horsepower loss for every rise of a 1,000ft. elev..The times I've been up to 14,000 ft, my ST1100's have not missed a beat (87). Never really noticed a change.
Sure noticed it when walking slightly uphill though!
STraymond's comment that at altitude there is less air going into the cylinders, creating lower TDC cylinder pressure, is correct, assuming a given throttle opening.Correction for that assumption, pistons are drawing SAME amout of air in cyls., just not as much OXYGEN content in what's being drawn in My normal riding elev. is 5,000ft., and everything goes UP from here in three out of four directions to over 10,000ft. elev. when traveling those three directions some 40-80mi. Cyl. compression or pressures has to do with compression ratios, NEVER altitude changes.
That's an interesting comment, John. When I was in Iowa this year ( first time since 1974 ). I was surprised to see on the pump at two gas stations " All Grades Ethanol Free ". I have never seen that anywhere else in my travels. Usually the pump says something like " May contain up to 10% Ethanol".Here in the heartland it’s almost impossible to avoid 10%. Snip. Snip .....
John
Yes, and Yes. Since only Ethanol gas available in my area, I do add a stabilizer (Sta-Bil marine formula), and have had no issues as long as I've owned it.Does anyone run 87 octane gas on your ST1100, and is it ok.