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Octane


Kregerdoodle

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Guest JGorom

Mine runs fine with no problems using the manufacturers recommendation...87 octane. I do try to avoid the ethanol blends...in our area the Sunoco stations sell a 10% ethanol blend.

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I've tried them all on numerous occasions over the years but have yet to ever see any improvements in performance or MPG using the higher octane stuff. So...I run the 87 about 99% of the time. Every once in a while I will run a tank of high end stuff through it just because of some notion that it might help clean things out a bit but even that is just an old rumor that doesn't really hold true.

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I run 87 with 10% ethanol, with absolutely no problems. Almost every station in Central IL has the 10% Ethanol and I use it in everything. Tried some high octane once in my scoot and actually got worse mileage.

Jay

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What fuel does every one use?? I have been using the highest Octane I can get get, but read that some just run Regular gas???

 

 

a higher octane has nothing to do with getting better performance or "cleaning things out". It just means that it takes a higher temperature to burn, and if your engine is designed to burn at lower heat, it will not completely burn a higher octane fuel. --it will not cause your engine to burn hotter.

 

The only time I have noticed a problem with octane levels is when driving in the western mountains where they sell 85 octane--my bike ran like s* there unless I put the mid-grade in.

 

The only benefit to running with 91 is to the company selling it to you.

 

Rip

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a higher octane has nothing to do with getting better performance or "cleaning things out". It just means that it takes a higher temperature to burn, and if your engine is designed to burn at lower heat, it will not completely burn a higher octane fuel. --it will not cause your engine to burn hotter.

 

The only time I have noticed a problem with octane levels is when driving in the western mountains where they sell 85 octane--my bike ran like s* there unless I put the mid-grade in.

 

The only benefit to running with 91 is to the company selling it to you.

 

Rip

I agree with Rip.

 

High octane fuel is usually recommended for high compression engines. The 2nd generation venture has a 10:1 compression ratio which is considered high. My understanding is that octane is used to prevent “dieseling” or “run-on” and like Rip said does nothing to boost performance (it’s been a long time since I’ve heard an engine run-on). My scoot seems to run fine on regular fuel. One thing I won’t do is tank up when the ‘station’ is being refueled and I tend to look for stations that have a regular turnover of fuel.

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All Royal Star engines use 87 octane. The 91 reading you see is how they rate them in Europe I believe.

... for what it's worth my bike came from the US (NJ), there is a mfg lable inside the seat trunk that recommends 91 octane.

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I've tried them all on numerous occasions over the years but have yet to ever see any improvements in performance or MPG using the higher octane stuff. So...I run the 87 about 99% of the time. Every once in a while I will run a tank of high end stuff through it just because of some notion that it might help clean things out a bit but even that is just an old rumor that doesn't really hold true.

 

Ditto on what Don says... but, I've been down to California a couple times and found I had to put some Octane Booster in otherwise the pinging was so bad I thought the engine was coming apart.

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Over this past year of my affiliation with this site I have noticed that out of 10 different responses to a question there may be 6 variants on opinions. That is the beauty of these forums. You get to see what lots of folks are doing on any given subject.

 

Here is another one.......

 

When I purchased my 05 RSV last May I asked my mechanic at the dealer which fuel to run. His reply was that since it is a high compression engine, it would be better to run Premium fuel. He also said that 10% Ethanol would be acceptable. I have been dealing with this dealer and this mechanic in particular for the past three years. He has always been very helpful and never once steered me wrong.

 

I'm no expert. That is why in addition to my warranty I have a maintenance contract with my local Yamaha dealer to perform all my service work.

 

During my younger days when I had multiple muscle cars and built my own high compression engines it was easy to hear and feel the difference that premium fuel provided over lower octane blends. The Expedition I recently traded ran terrible on low octane, but my full size pickup runs fat, dumb and happy on the cheaper blend.

 

For me, the difference in cost for premium fuel in my scoot is minor... so I run premium. Obviously others are having success with the lower octane. Just see what works best in your scoot.... and ride that puppy!!!!!!

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I remember back in hi school Standard had three grades. I can't remember the octane of the lower two, regular and ethel, but the 'Supreme' was 102 octane. Made my POS 53 Ford run like it was new... :)

 

I also remember a sales meeting back in Ithaca NY where a bunch of us were trying to catch a flight to Kennady out of Thomkins County, and we ran out of gas in the rental just before getting to the airport because the idiot salesman from SoCal was to cheap to spend a couple of bucks on gas for the week we were there. So we sat there by the side of the road and watched as our plane took off. We made the guy hoof it to get fuel. So what does he do... We didn't know it but he goes and gets a gallon of avgas. We get the car started and finally get to the terminal. We pile out of the car to see what kind of conections we could salvage, and when the jerk turns the key off the damn rental car sat there and just kept dieseling. Never did stop. That's when he told us about the source of the fuel. Very high octane.... Sorry...wandering off and telling stories again....:backinmyday:

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If I understand this correctly... higher octane gas is used for engines with higher compression. The point of high octane gas is to retard the burn rate of the fuel to keep the engine from suffering "Preignition Knock" allowing the engine to run correctly respective to it's ignition timing. "Dieseling" can also happen as a result but is not the primary focus.

 

10:1 compression ratio is considered to be the separation point of a high compression engine as I understand it. The Royal Star engine will run fine on 87 Octane fuel in most cases. I hear it mentioned at higher elevations you would want to run a mid grade.

 

Higher octane fuel burn's slower and would not be the best choice for a engine that will burn a lower grade fuel. It is lower in octane not quality and in fact imparts more energy when burned then its higher octane cousin.

 

Having heard this discussion many times on a couple of forums it always seems to come down to two points... Run what the manufacturer says or better... run the lowest octane the engine will tolerate without pinging. It saves you money and the engine will run its best.

 

 

That would be my 2 cents for what it is worth.

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So what does he do... We didn't know it but he goes and gets a gallon of avgas.

 

On a side note, don't run Avgas in any car built after 1976. It still contains tetraethyl lead which will plug up your catalytic converter...

 

 

 

I run Regular in my vehicles. The RSV does not yet have EFI so you wont get higher gas mileage using premium fuels.

 

When I had my 1986 Corvette, it cost me less per mile to run premium over regular fuel.

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If I understand this correctly... higher octane gas is used for engines with higher compression. The point of high octane gas is to retard the burn rate of the fuel to keep the engine from suffering "Preignition Knock" allowing the engine to run correctly respective to it's ignition timing. "Dieseling" can also happen as a result but is not the primary focus.

 

10:1 compression ratio is considered to be the separation point of a high compression engine as I understand it. The Royal Star engine will run fine on 87 Octane fuel in most cases. I hear it mentioned at higher elevations you would want to run a mid grade.

 

Higher octane fuel burn's slower and would not be the best choice for a engine that will burn a lower grade fuel. It is lower in octane not quality and in fact imparts more energy when burned then its higher octane cousin.

 

Having heard this discussion many times on a couple of forums it always seems to come down to two points... Run what the manufacturer says or better... run the lowest octane the engine will tolerate without pinging. It saves you money and the engine will run its best.

 

 

That would be my 2 cents for what it is worth.

you and red neck are the only two that have hit the nail on the head in this thread. high octane fuel does burn slower than low octane fuel. that is the only difference in the two. if you use high octane fuel in a low compression engine it has a very slow flame front during combustion and will produce less hp.,and give worst mileage. in a high compression engine where the fuel and air mixture ar compressed into a smaller area the flame will jump from one fuel molecule to the next faster because the molecules are closer together causing an explosion rather than a smooth burn. this explosion is called detonation.the pinging noise you here is the burning flame front from the explosion hitting the internal metal surface of the piston and combustion chamber so hard it makes the metalic sound you hear as pinging. very distructive. so they add an additive to the fuel to slow down the burn rate of the flame front. a friend of mine had a cushman eagle motor scooter and swore by premium fuel in his 8 1/2 to 1 compression engine. he put it on a dyno and got a 1 hp. gain by switching from premium to 87 octane. i could really get tecnical on this subject cuz i've built alot of high performance engines. but this is the simplest way i can think of to explain it. bill
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There is a lot of info on this sight about that. Use search and type in Octane. All kinds of stuff comes up.

 

I have tryed them all. For my 02 RSV 87 octane runs the best. In hot weather, just can't imagine running anything higher then 87 octane.

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Another explanation on burn rate on the two and why higher octane runs hotter. With a slower burn rate, the fuel is still burning as the piston is bottoming out, therefore saturating the entire cylinder wall with burn. With lower octane fuel, the heat is more in the top part of the cylinder and head area, and is easier to remove from the engine.

RandyA

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  • 2 years later...

Thought I'd resurrect this '08 thread instead of starting a new one.

 

Until a few weeks ago, my '99 RSV has never had anything in it but 89 octane. Lately, it seems like it's knocking a little, and I am wondering :scratchchin: if this could be a fuel issue or a valve adjustment issue. So I've run a few tanks of 93, and it does seem to perform a little better and the knocking is all but gone now. So I'm thinking that as the engine gets a little older and more miles on it, that maybe a higher octane is now in order.

 

Anyone have a similar experience with higher milage RSV's (50,000+ miles)?

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