When filling up your 4 wheeler what octane do you use? Some of oour higher octane uses ethanol. I've heard that sometimes that not what should be used. What do you guys use to fill 'em up?

 

93% and if i buy 87% i have stp octane booster.. add a cap full of that with 87% and it seems to work

 

87 octane normally, but every once in a while I'll use 93.

 

Mncat,
well I'll be the other end of the spectrum. in my truck, (stock) quad (prarie 650 up 1 size on the mains & a little airbox work) I run regular, in my street bike (6 degrees more ignition advancethan stock, airbox & pipe work, & up 8 jet sizes in the carbs, I run mid grade.

I have found out that the octane does NOT make power, it keeps the spark from detonating to fast, & reduces the flame front. therefore I run just enough octane to keep detonation at bay (preignition) I have found by doing this it runs cooler & makes more power. Now the exception to the rule is high compression & more ignition advance earlier, that would require more octane in the fuel. I know that it is less than 50 cents a tank diffrence, but so far it has done just fine. when tuning & running hard on my bikes (2 wheelers) I would run premium while changing ignition advance curves, but that was to check 1/4 mile WOT response, so I wanted to take the fuel question out of the equation. I ended up backing off from 8 degrees more advance to 6, & running midgrade. it works for me.no detonation..

as far as ethanol, I think that in your owners manual it will state that up to a certain percent ethanaol can be used, as well as some of the other additives.

 

I use 87 octane nothing more....that is what they are designed to run on.

 

it may be what they say to run... but i still run 93..
my scrambler was supose to have 87..but ran alot better with 93.

 

Yep, I have also heard that the higher octane isn't always your best choice. Our mid octane is the ethanol blend. So, I've been torn between the lowest octane and the highest one

 

Only run the highest octane necessary to prevent detonation. After that you are wasting your money. I run 87 in my truck, 87 in my Wolv, and 93 in my Cannondale.

Most 4 wheelers are gold on 87, some need a lil more. Check your compression ratio and go from there.

 

Yup. That's the way to do it.

The only time more octane is needed is to prevent detonation (as said above). And that's caused by:

1) High compression ratio.
2) High degree of timing advance.
3) Boost or juice (turbo, supercharger, or NOS).

Otherwise you're wasting money. If your bike has a heating problem, then you can try premium to see if it fixes the problem. (It would have been caused by 1,2 or 3 above). Otherwise, just flushing good money.

 

Mn Cat,
In Minnesota all fuels are of an ethanol blend unless stated on the pump (for recreational use).
It's in the 87 your buying also.
When they first started selling ethanol they only put it in the 87 and marked the pump, then they put it in all gas (and labeled nothing) but the recreational types and high performance enthusiasts stated their concerns so they took it out of the 92 octane and labeled the pumps so