low octane @ high altitude

[tedkraus]

Just curious those who have ridden their motorcycles above 4 or 5 thousand feet.  As you are aware regular grade gas sold typically has a lower octane rating at altitude. Where I live now 7200ft regular is either 84 or 85 (r+m)/2.  So opinions on low octane gas?

[guywheatley]

If it's not knocking, don't sweat it. If it is, go up until it stops.

Blog Being fuelish



Blog Being fuelish

[tedkraus]

So I think I will try the low octane stuff in the bike, it seems to be fine in the car....Just nervous I guess.

[TLRam1]

I used low octane while in Colorado with no pinging I can remember.

[lragan]

I bought the cheapest gas at each fill up in Colorado, and the bike ran great.  Even over passes at 12,000 feet.  Also got great mileage.

[hop along]

+1 to what Iragan said... ran great, great mileage

[tedkraus]

I put 85 octane in the strom today, don't think it made a difference I could notice. I will run 85 unless I am leaving town for Nebraska, then I need to put some higher octane in before the altitude falls off steeply. Hopefully save a few bucks with the 85.

[ggeezer]

I normally run regular except in very hot weather combined with hard riding. The bike generally runs cooler on premium fuel and this is why.
On older bikes with carburetors and more primitive electronics, ignition timing is a compromise at best. The hotter the engine, the more likely there will be per-ignition even if it is so slight that you cannot hear it. This degrades efficiency and the engine has to work harder to maintain performance. More work, more heat, requiring more work resulting in more heat. Air cooled engines with high compression ratios are most effected. Liquid cooling helps but doesn't totally eliminate the problem. The energy content of non-ethanol based gasoline of different octanes is the same. High octane fuel is just more stable.

Orv.