octane

[elevatorman]

what octane fuel do you use and why? just curious if there is a advantage and makes the moter happy. do you run fuel additives and why? thx guys for your response.im trying to learn whats best for my 250es.

[rjs89ia]

low compression low octane high compression high octane. i run 91 in my stock 400ex sometimes 87 just depends on the price of 91 but thats what it calls for in the owners manual i believe so thats what i run. I run 100LL avgas in my esr 310 engine on my R because i have the high compression dome. I also called esr to verify what could be run with this dome which is an updated one that you could run 91 during normal riding and any heavy loading like racing or dune riding with paddles i should run 110. I chose a happy medium and avgas is easily excesible for me. you should always try to run the lowest octane point for your application so unless your hopped up full blown race 87-91 octane would be best.

[Flyingw]

Unleaded 87 octane 100% gas is all the ES needs. Dont run blended gas if you can avoid it.

[yaegerb]

I run 93 octane in my 1985 250R (stock motor) and I run VP 110 octane in the 200x (bored and stroked motor with a 13:1 comp. ratio).

[elevatorman]

that answered my question, thanks alot...

[chuk85]

i run a mix of 4 gallons of av gas with 1 gallon of tolulene and 28 ounces of kerosene then golden spectrum at 50:1 in my 250r.

my compression is way higher than stock, i have not done the math to know for sure but the motor builder told me it would not run on pump gas.

this mix sounds odd i know, some sand rail guy came up with it because the slides in there carbs kept freezing (being im in oregon and its usually cold at the dunes).

my old boss ran it in his car and didnt want to pack different fuels for his car and quads so just ran it in everything

[barnett468]

Hello Elevatorman


Looks like you have a solid general consensus so I thought I would post this for just a little better explanation. Chuk85 is being a little “exotic” with his mix and it would require a bit more explanation that is not necessary or relevant to what you are doing however.

The following is some condensed information and recommendations from technical articles written about the effects of octane.

1. Run the LOWEST octane possible for your motor which still prevents detonation.

2. Using higher octane in a motor in which it is not required will NOT provide increased HP and can actually reduce HP in some cases.

3. Leaded gas is the best adding a quality lead substitute to non leaded gas is also beneficial however it is a bit of “overkill”. It mainly reduces wear on the valve face and valve seats.

4. AV GAS – It will work but is not ideal [complicated but I’ll post info if you want] if gas above octane levels above that of pump gas are needed. I ran it in my 64 GTO in the “old” days but can’t get anywhere near a private airport now due to 9-11.

[tri again]

Not sure of the octane in Oregon but they call it:
non ethanol premium.
About a dollar more per gallon than the 'best' 15 ethanol.
If I can't get to the local airport, Oregon allows non ethanol gas at marinas for boat motors.

Everything just runs cooler and happier.

My tractor would throw heat waves off the muffler about 8" high,
I came off the field to refuel and only had the expensive non etoh fuel.
Needing to finish the field, I put it in the tractor.
Lo and behold, it pulled waaay happier and the heat waves off the muff were like an inch tall instead of 8".
Nice to keep the tanks full too because without alcohol, it has less incentive to grab and hold moisture to rot the tank seams.
Additives?
MAYbe some marvels mystery oil in the gas if I need to run consecutive hours over 90*F. Upper end lube approved for small airplane engines.

Lead additive? Maybe not necessary for valves.
Zinc / phosphorus oil additive?
...seems to be more important for square cut valve lifters.
I DO like heet, that aclohol fuel drier, when rinsing out freshly hosed, pressure washed gas tanks to get moisture out of the deep seams in the tank.
I keep all my tanks and gas cans full so they don't sweat and condensate moisture from the air.
Had 2 trikes start with 1 kick after 6 months.
Tempted to try some sorrt of seafoam or stabil but these trikes never seem to sit long enuf to be a problem especially with the non ethanol fuel.

Where in Oregon ru?
We're near UoO

[tri again]

Unleaded 87 octane 100% gas is all the ES needs. Dont run blended gas if you can avoid it.
What is 'blended' gas?
I know my es and sx's have no problem with street level lawnmower pump gas
but they sure seem happier with the non ethanol stuff.

[tri again]

i run a mix of 4 gallons of av gas with 1 gallon of tolulene and 28 ounces of kerosene then golden spectrum at 50:1 in my 250r.

my compression is way higher than stock, i have not done the math to know for sure but the motor builder told me it would not run on pump gas.

this mix sounds odd i know, some sand rail guy came up with it because the slides in there carbs kept freezing (being im in oregon and its usually cold at the dunes).

my old boss ran it in his car and didnt want to pack different fuels for his car and quads so just ran it in everything

FlyW can probably help but I know carb ice can happen at 60 degrees or even higher..
Baaaad if you need power on landing.

[HappyTrail]

Hello Elevatorman


Looks like you have a solid general consensus so I thought I would post this for just a little better explanation. Chuk85 is being a little “exotic” with his mix and it would require a bit more explanation that is not necessary or relevant to what you are doing however.

The following is some condensed information and recommendations from technical articles written about the effects of octane.

1. Run the LOWEST octane possible for your motor which still prevents detonation.

2. Using higher octane in a motor in which it is not required will NOT provide increased HP and can actually reduce HP in some cases.

3. Leaded gas is the best adding a quality lead substitute to non leaded gas is also beneficial however it is a bit of “overkill”. It mainly reduces wear on the valve face and valve seats.

4. AV GAS – It will work but is not ideal [complicated but I’ll post info if you want] if gas above octane levels above that of pump gas are needed. I ran it in my 64 GTO in the “old” days but can’t get anywhere near a private airport now due to 9-11.
Barnett is right on the money I Just would like to add that the higher the octane the more carbon build up you will have in your combustion chamber. High octane is to help limit pre-ignition which can harm your motor. A trained ear can hear the pinging or knocking sound of pre-ignition which is more noticeable at lower rpm's. So yes run the lowest possible.

[tri again]

so? my question now is:
Is it just a waste to run octane higher than necessary to prevent pinging?
Is there anything else it's not good for except just a waste of $?

[barnett468]

Hello


"Lead additive? Maybe not necessary for valves.
Zinc / phosphorus oil additive?
...seems to be more important for square cut valve lifters."


More info from tech articles.

Lead is the most important additive when it comes to protecting valves and extending valve life NOT ZDDP/oil. In short these two chemicals not only act on two different principles, the valves are constantly "washed" in fuel but not oil. Therefore it makes more sense to run a valve "protectant" in the fuel and not the oil. The oil on some models is prohibited from running down the guide by the use of "positive" valve seals. It is further block from oil in the crankcase by the piston rings.

In 1974 all car models were required to run "unleaded" gas. To counter the damaging effects running non leaded gas would potentially have on the valve seats, the seats were "flame hardened". In some instances the exhaust valves were hardened also but not the intakes so the intakes were the first to fall victim of the unleaded gas and many cars required valve jobs much earlier than their lead guzzling predecessors.

[barnett468]

so? my question now is:
Is it just a waste to run octane higher than necessary to prevent pinging?


Is there anything else it's not good for except just a waste of $?


1. According to the tech articles and my previous post this is absolutely 100% correct.

2. Also as mentioned in my previous post the tech articles say it is NOT good for increasing HP when used in motors that do not require it. It could actually cause your motor to run COOLER since it is less volatile than pump gas, at least under low compression situations. This is generally why it reduces detonation/pinging.

[elevatorman]

Thanks guys. it is neat how you break down the subject and hit from all angles. I can walk away a little smarter and i feel lucky to have you answer my questions objectively.

[HappyTrail]

Thought I might add again the major cause of pre-ignition or pre-detionation. As a motor heats up so Does the sharp edges of carbon build up in the combustion chamber. This also goes for any sharp edges in the combustion chamber itself. When the edges get to hot they start to glow and cause the air fuel mix to ignite before the spark plug fires. Hence pre-ignition and bad timing hence bad performance. Yes octane only cools off these sharp edges so the spark plug has ignition control. I drive an old 85 GMC work van That's been around the world. It only likes 92 octane these days to run smoothly. Sucks for me. Now when it comes to passing my state emissions test my van only passes on 87. So I have to deal with some knocking and pinging and run lower octane for an 1/8 a tank Just to please the state. Octane lowers running temps like Barnett said and produces for hydro-carbons in the emissions.

[chuk85]

Not sure of the octane in Oregon but they call it:
non ethanol premium.
About a dollar more per gallon than the 'best' 15 ethanol.
If I can't get to the local airport, Oregon allows non ethanol gas at marinas for boat motors.

Everything just runs cooler and happier.

My tractor would throw heat waves off the muffler about 8" high,
I came off the field to refuel and only had the expensive non etoh fuel.
Needing to finish the field, I put it in the tractor.
Lo and behold, it pulled waaay happier and the heat waves off the muff were like an inch tall instead of 8".
Nice to keep the tanks full too because without alcohol, it has less incentive to grab and hold moisture to rot the tank seams.
Additives?
MAYbe some marvels mystery oil in the gas if I need to run consecutive hours over 90*F. Upper end lube approved for small airplane engines.

Lead additive? Maybe not necessary for valves.
Zinc / phosphorus oil additive?
...seems to be more important for square cut valve lifters.
I DO like heet, that aclohol fuel drier, when rinsing out freshly hosed, pressure washed gas tanks to get moisture out of the deep seams in the tank.
I keep all my tanks and gas cans full so they don't sweat and condensate moisture from the air.
Had 2 trikes start with 1 kick after 6 months.
Tempted to try some sorrt of seafoam or stabil but these trikes never seem to sit long enuf to be a problem especially with the non ethanol fuel.

Where in Oregon ru?
We're near UoO

portland.

oh yea? hit the dunes yet this year?

[ngunter2]

I run Highest pump octane (93?) In my all stock tri-z. Should I lower the octane? From the previous information. I see yes? I thought that higher octanes made the engine "happier" and last longer. So i am wrong?

[barnett468]

I run Highest pump octane (93?) In my all stock tri-z. Should I lower the octane? From the previous information. I see yes? I thought that higher octanes made the engine "happier" and last longer. So i am wrong?

Hello

Please slowly read the posts, you will understand them better. Run whatever your manual recommends, 93 is typically ok for stock compression bikes.I'ts complicated.

[kb0nly]

Just plain old ethanol blended fuel here... Nothing special goes in the tank, nor has it in 20+ years of riding ATC's and ATV's... We don't even have non-ethanol gas here at most stations.