Question for you gasoline Guru's

[Adirondack Bill]

Does a higher octane fuel burn hotter than a lower octane fuel?  I know the higher the octane level is in gas, the more resistant it is to  igniting. And then we throw ethanol into the mix. A local gas station sells a 91 octane (non-ethanol) gas and that's what I usually put in my Valk. Is this higher octane fuel causing the bike to run hotter?

[Pete]

Probably not in normal riding.
An even if it did it would not be much and in a water cooled/thermostat engine a few degrees in the combustion chamber either direction matters little.

But unless you have advanced the timing high test is of little to no value, except the extra $$ you spend.
I use 100% regular and it works great. A few times I have had to use high test to stay with 100% gas, I could tell no difference.

[KUGO]

"A local gas station sells a 91 octane (non-ethanol) gas and that's what I usually put in my Valk. Is this higher octane fuel causing the bike to run hotter?"

I'm going to step up here and try to answer your question, at the risk of looking like a complete ignoramus to those more knowledgeable, yet less helpful.  An engine is basically "tuned" for a specific octane level.  Some of my high-performance cars have required it and you pay the price with knocks and pings if you stress those kind of engines on "whatever was available at that one-pump place in the country".  (Which is sometimes simply unavoidable.  Just don't hammer the car with that stuff in your tank.  And consider a change of fuel filter ASAP if the station looked very iffy.)

I had an MSD (brand) controller  put into the dash of my '80 'Vette that had a very custom motor built for it.  Stroker motor, nitrous, the works.  It allowed my to advance the distributor curve at will based on what I was up to.  Cruising down I-80?  Dial it back.  Doing a Quarter Mile and using nitrous?  Dial it up.  That simple.  No damaging knocking/pinging in the engine.

No, it does NOT make your engine run hotter to have a higher level of octane in your tank.  I always ONLY use 91 or better octane, NO ethanol for my '14 Valk.  (Some will say you're wasting your money.  I consider it cheap insurance and it helps when you have to fill up somewhere strange and get a bad load.)  Your bike will run hotter, however, if it pre-detonates  (pings) due to bad gas, lower octane, etc.  Hope this help ease your concerns.  We'll find out how stupid my response is, I'm sure, when more those more knowledgeable chime in to refute what I've told you.  

[goldstar903]

It's a low compression engine. It only needs 87 octane. 

[Crabballs]

It's a low compression engine. It only needs 87 octane. 

BINGO!!!  We have a winner!  Best and simple explanation.  I use the cheap stuff in the Valk and it runs great.  On a side note, I have a 2013 F150 Limited with the 3.5L EcoBoost, which is a twin turbo lawnmower engine that runs about 20# of boost and it never seen a drop of high-test.  Plenty of power and torque.  Plus the manufacturer recommends the 87 stuff and that's what it gets.

[st2sam]

It's a low compression engine. It only needs 87 octane. 

Yep,^^^ that's a Double Bingo goldie.

However, every now and then I'll fill'er up with corn free.
It cost twice as much, but I get a couple extra miles outa the fill up. 

[Pete]

Actually it is a moderate compression engine with good cooling, proper spark plug location and is designed to run properly on 87 octane (timing and timing advance).

If unchanged why use anything else - I guess so you can pay more.

[AdrianR]

Octane, not important, ethanol blows. Get gas without it if u can. If not, treat it with a fuel additive. You'll get better performance and mileage.

[Robert]

A higher octane fuel will not burn hotter it actually burns cooler and longer and its what higher octane does. Detonation or knock is the uncontrolled burning of the gas that preignites a flame front. Sometimes the choice of octane booster is ethanol.

The real truth of the matter is our bikes could run on just about anything. The non ethanol fuel is a good choice but you might like to try a few tanks of the premium and regular to see where the bike is happiest. I use premium all the time because its what I use in all my vehicles. The difference in price is less than a dollar and sometimes the bike does run better on premium. My cars all have knock sensors on them and most cars do, so when you use regular and if the car knocks it retards the timing and you could loose power and MPG. Its all in what each vehicle is happy with and to check you have to check MPG and seat of the pants power and smoothness. The Non Ethanol is less corrosive on the fuel systems but its not a major difference. With non ethanol you should gain some MPG also since the BTU value of ethanol is lower than gas.