Octane

[SIZE=14pt]I’ve searched the archives trying to get a fix on the different octane used and noticed results. I’ve found nothing specific to the point. So, the questions: [/SIZE]

1. what octane do you use

2. what result have you found

3. Speed improvement

4. mileage difference <_<

Oh God. It's an octane thread. Somebody shoot me!

I use the octane recommended by Yamaha in the owner's manual. Mininum of 86 IIRC. So 87 octane works just dandy, unless you experience detonation (pinging) which is not very common.

As for speed or mileage improvement, octane has nothing to do with those things. Me thinks you have some mis-conceptions about octane based on those questions. Google "octane" and there will be a wealth of info.

And, moving this thread to it's proper home..................

Here's a link for ya: Clicky Here

SkooterG said:

Somebody shoot me!


Here's a link for ya: Clicky Here

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Where, pray tell, are you getting these quotes?

Lift the seat. There's a label. Read it. It say to run 91 (RON). That roughly equates to 87 ((R+M)2).

- The Observer

twowheelnut said:

Lift the seat. There's a label. Read it. It say to run 91 (RON). That roughly equates to 87 ((R+M)2).
- The Observer

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ScooterG got it right! 86 is the bottom number!

I almost always fill my FJR w/ fuel that contains octane.

GunMD said:

I almost always fill my FJR w/ fuel that contains octane.

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Don't do that, octane causes tickers!

Regular here in my 2003 since it was new. Just like the owners manual says.

https://www.mcnews.com/mcn/articles/Article_Index_Jan04.pdf

2/2003 "Octane for Dummies"

I don't have the issue (I pass mine along) but maybe someone else does.

Compression ration 10:8:1 will run 87 octane just fine. Never ran anything higher in my 05.

My 03 gsxr is 12:0:1 and requires 91.

The higher the compression the more octane you need to eliminate predetination due to the fuel can self ignite under pressure if the octane is lower, bad!

Many of todays high performance sports cars have knock sensors that even if they require high octane they will sense the knock and retard the timing to adjust. So you could use 87 in a car even requiring 91 if you just needed to commute and then put in 91 if you wanted full performance.

Many times a vehicle requiring high octane will have no problem with 87 unless you are really hammering it or going up hill or towing or something where the engine comes under heavy load.

Running 91 in an engine that only requires 87 doesn't give you any better performance but does cost more.

While using the knock sensor feature and retarding timing can produce poor fuel mileage usually the trade off is still cheaper than paying for 91 fuel in todays high prices.

Um...yeah....what sparky said.

Octane requirements are determined by compression ratio, ignition curve, combustion chamber dsesign, valve timing, swirl and much more.

Using too high an octane fuel can actually decrese mileage and power as the fuel resists ignition and the octane enhancers generally have less BTU/litre than gasolene itself.

panthercity said:

Octane requirements are determined by compression ratio, ignition curve, combustion chamber dsesign, valve timing, swirl and much more.
Using too high an octane fuel can actually decrese mileage and power as the fuel resists ignition and the octane enhancers generally have less BTU/litre than gasolene itself.

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Now your starting to flood my head with TMI

What no stroke information in there???

sparky3008 said:

panthercity said:

Octane requirements are determined by compression ratio, ignition curve, combustion chamber dsesign, valve timing, swirl and much more.

Using too high an octane fuel can actually decrese mileage and power as the fuel resists ignition and the octane enhancers generally have less BTU/litre than gasolene itself.

Click to expand...

Now your starting to flood my head with TMI

What no stroke information in there???

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Just read what I typed twice as fast...

OK....it is either "preignition" or "detonation." "Predetonation" just does not exist....LOL.

"Premium fuel resists ignition".....????.....uh.....NO. Premium fuel is no harder to ignite than regular fuel and does not cause power loss.

The eternal premium vs. regular debate goes on forever and some of the old wives tales out there surface due to people's experience with oxygenated "premium" fuel that causes problems. Quite frequently alcohol is added to premium fuel to increase the octane rating so an alcohol blend will burn a little slower and cause a slight power loss. That confuses the issue because it is assumed to be because of premium. Regular fuel with alcohol added works the same way. As long as it is premium gasoline it runs the same as regular...it just resists spontaneous combustion of the end gas/detonation better than lower octane fuel.

The octane rating is a measure of the fuel's ability to resist spontaneous combustion of the end gas in the chamber...which is commonly called detonation. This occurs AFTER the spark plug has ignited the charge and the mixture has burned partially. The rising heat and pressure in the chamber (from the burning mixture) causes the end gas to spontaneously combust. Key here is that it occurs after the spark plug initiated combustion at the correct time.

Preignition indicates combustion in the chamber that initiates BEFORE the spark plug ignites the mixture. Octane rating has absolutely no effect on this phenomenon. Hi octane fuel can preignite just as easily as lower octane fuel as the ignition source is usually an overheated spark plug tip or a piece of glowing carbon in the chamber.

This whole discussion gets confusing because spark plug tips often overheat due to excessive detonation at high loads. Thus, there CAN be detonation induced preignition that might not have happened if a higher octane fuel had been run...or colder plugs.

This is why I always run premium in my FJR.... It simply gives you more insurance against detonation. Not that it is necessary. I just like the added security and it doesn't hurt anything. Besides, from the fuel analysis from the field that I have seen over the years the premium fuel marketed by the major suppliers always has the highest concentration and best additive package of detergents and cleaners. Not that you will always get the best additive package in every tank of premium but you do stack the odds in your favor against injector deposits, inlet valve and chamber deposits and the rock hard deposits on exhaust valves. Costs a little more but I really don't ride to save money, personally.

jestal said:

Blah, blah, blah...............................Costs a little more but I really don't ride to save money, personally.

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All good information except for the last part...........this was the excuse I used for wifey in order to buy the bike in the first place......... :lol:

NC

I'm sticking with regular.

Likewise. I'll stick with what Yamamama recomends and continue to believe my dyno results over that past 30-odd years. Had no idea that old wives ran dynos...

C&C said:

I'm sticking with regular.

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As am I. Though Jastel makes a valid point regarding premium gas generally having a better additive package of detergents and cleaners.

However, the bikes are my sole means of transportation, and I do have to look at the money issue to some degree. Riding over 30,000 miles a year definitely makes the price of Regular seem more attractive over the long haul.

Now, my R1, that's a different story. It has a fairly high compression ratio of 12.4:1, and you better believe that engine sees nothing but premium.

Damn you Jestal, I thought they had you confined to the oil threads.!!

Good info and after reading it about a half a dozen times I started to make sense of it

Very true on the additives but in my XTerra I will stick with 87, 91 in my GSXR and well plain old Diesel in my Diesel :dribble:

What mixture do you recommend for my 2 stroke weed eater. I think I am running 50:1 :lol: