What octane gas are you using?

[SoftailDave]

My engine is pretty much stock except for an Andrews EV27 cam, stage 1 carb kit and Samson exhaust.
I have been filling up with premium 91 octane gas. Am I wasting my money?

[JC 92FXRS]

I'd keep using the premium...it's just better stuff (especially if the bike sits for extended periods) and for the difference in price you'd hardly notice it, plus you've got a cam in it.
That being said...mine is bone stock, except for the slip-ons and I've run regular in it numerous times, simply because in some of the smaller farm stations around here, all they've got is a deisel pump and a regular...so regular goes in. I must confess, I can't tell the difference when it's running regular. Still if I've got the premium option, that's what goes in.
Cheers, Jeff

[Norton Commando]

If your engine doesn't "ping" with regular fuel, then you are indeed wasting your money by buying premium.

[Harpo]

Softail,

Premium gas isn't any "better" than regular gas.  It simply has additives that prevent it from burning (to soon) under compression.  Hence the higher the octane the more compression that can be run.  Regular gas has just as much explosive capability as premioum gas, it just ignites quicker.  If your stock compression bike doesn't ping or rattle, then regular is fine.

[ScottFree]

What's your owner's manual say? Most of the carb'd Evos were set up for regular (87 octane); the fuel injected models (at least some of them) required premium. My '90 (carb) FLHTC runs just fine on 87 octane.

One thing to consider: in many places the only way to get gas without ethanol is to buy premium (f'rinstance, the KwikTrip stations in Wisconsin sell ethanol-free "Recreational Premium," but their regular and midgrade both have ethanol. If ethanol is a possible problem (you're going to store the bike for a while in a humid environment), you may want to use an ethanol-free premium.

[05FLHTC]

Wasting yr money, the motor will tell ya if it needs premium...it will be very obvious.

[mp]

Premium gas will burn slower in the same engine compared to regular.  It can burn as fast in a higher compression engine as regular will burn in a lower compression engine.  Regular will burn too fast in a higher compression engine and cause detonation, literally, meaning the fuel is exploding rather than burning.  You don't want explosions in your combustion chamber.  On the other hand, if you use a higher octane fuel in an engine without the compression for it, you're not getting a fast enough rate of burn and not getting all the energy out of the gasoline and your mpg and power will always suffer.  However, an older, high mileage vehicle may benefit from higher octane gas than when it was new because of carbon deposits in the combustion chamber which reduce its size and increase its compression.

[SoftailDave]

Thanks for all the responses and explanations!

I think I will try regular on my next fill as my bike has stock pistons etc and is not high compression.

[glideryder88]

I have run both in my '88 electraglide and find no differance,so usually just run the regular gas. I do how ever fill it with premium gas with a stalilizer for winter storage.

[badcooky]

Premium in all my engines.

[CaptMike]

One of my pals pulled gas for a living.   The current shelf life is much shorter that what it used to be...  He said in many cases they'd load him with Premium as Regular to get rid of it.  Legally they can Dump Mid or Prem in the Regular tanks.   In many cases there's absolutely no telling what grade you are buying.    He also said never buy gas when you see a truck delivering.  When they drop it in the tank it will stir up all the "Potty mouth" that's in the bottom of the tank (and they all have it).   Ever see the driver drag a hose across the ground?   

[mfalba]

Just curiously, at what compression would you consider premium over regular?

[badcooky]

Just curiously, at what compression would you consider premium over regular?

I spose anything over 10 to 1.
Each to his own, i run my engines hard with all the advance I CAN GIVE THEM THOUGH.

[hogpipes1]

Softail,

Premium gas isn't any "better" than regular gas.  It simply has additives that prevent it from burning (to soon) under compression.  Hence the higher the octane the more compression that can be run.  Regular gas has just as much explosive capability as premioum gas, it just ignites quicker.  If your stock compression bike doesn't ping or rattle, then regular is fine.

Right on the $$$

[hogpipes1]

Harley says to use  prem 91 to cover there ass. i never use it but my 85 frx and 01 xl will ping when hot . i use a shot of octane boost  when hot  takes care of that issue. Winter weather with your cars/trk when really cold ---- and slow cranken  reg gas will fire off sooner to get u running.

[robflstc90]

 I say let the engine make the decision for you. Premium does make a world of difference in some vehicles. Some of the trucks I've owned got significantly better mileage on premium. So it was cost effective to run it. My bike 1990 FLSTC gets better mileage on premium. So I run premium in it. My present truck gets about the same regardless the octane. So I run 87 in it. The oil you use can make a difference in mileage as well.

[Hillside Motorcycle]

I believe that a T/C, (I know, not an Evo) service manual, refers to the use of 91, in bone stock bikes.
Scott

[prodrag1320]

use the lowest octane that dosnt detonate.in my bagger (127"),i HAVE to use 93,but in the rest of my cars & stuff,just regular 87)

[dakota224]

No ethenol in Premium here, thats what i use.   

[speed limit]

cam2 100 proof ( i love the smell of race fuel in the morning ! )

[Chameleon90]

I run premium all the time in my 90 FLHTC with Stage 1, regular will ping when I run it.  I tried one gallon of Turbo Blue 110 octane and filled the rest of the tank with 87 octane and it ran quieter yet. 

Of course I have been told that I can run 87 octane all the time...

[GaryD]

I never run premium in any vehicle - Harleys or Vettes. I will never buy a vehicle that HAS TO RUN on premium.
My Harley manual does not say I HAVE TO USE PREMIUM.

If the manual says "requires" then you usually need to - if it says "recommends" then you don't have to use it.
Some bikes are just finiky and run better on 93 or even 91. Luckily I've never had a problem - for years or thousands of miles.

I have read so many magazine and newspaper Q&A columns and they all say pretty much the same thing as above. The computer will adjust for whatever you put in.

Now if I were to go to the track, then I would want the full potential of the engine and would more then likely use premium.  For everyday riding = NOPE.


I'm not giving our enemies any more money then I have to. 

Bottom line - try a tank or two and see for yourself if it works in YOUR engine.

[ScottFree]

The computer will adjust for whatever you put in.

Slightly off-topic story here... some years back my 75-year-old mother-in-law and her 80-year-old boyfriend drove to Florida in her Buick Ultra (with the supercharged 3800 V-6). Long story short, she broke her hip down there, so wife and I flew down to bring 'em back: wife and her mom flew back, boyfriend and I drove back in the Buick. I was surprised at how sluggish the car seemed--accelerating, merging, passing, it seemed no faster than the regular Park Avenue. I expected a lot more punch from a car with a blower.

Someplace in north Florida, I stopped for gas. Seeing the "PREMIUM UNLEADED" sticker in the fuel door, I filled it with the expensive stuff. Boyfriend said, "Why are you wasting your money? We always run the cheap stuff!" Whatever, said I, and got back in the car. On the ramp back to I-75, I floorboarded the thing, as I'd done before, and... ZOOOOOM! The afterburners kicked in. Eighty in nothing flat. Obviously the computer, sensing the crappy gas, had cut back boost and timing to keep from blowing up the engine.

Back home, I asked my brother-in-law (who lived down the street from Mom and worked at a car dealer) what was up with running the cheap gas in a car that preferred premium. He said GM assured him that running on regular wouldn't hurt the engine... then he said, "do you really want a 75-year-old woman and an 80-year-old man driving a car that goes the way that thing does on premium?"

Had to admit, he had a point there...

A few years later, I inherited the car. Ran it on premium till gas prices went way up. Then I tried regular to save money, only to find the gas mileage (as well as the performance) dropped so much that it was actually cheaper (in terms of miles per dollar) to run it on premium. Not to mention a lot more fun.

[GaryD]

That's what I said. If you want the full potential(track time) by all means use premium. If you are just riding around town or cruising down the super slab, regular is more then good enough.  I saw very little difference in mpg between the two.

If it makes people feel warm and fuzzy to use premium, go for it.