Fuel Grade?

[Twism86]

Which fuel grade does everyone use in their bike? The previous owner always used regular (87). Should i continue doing so or use higher? I always though 93 was best, as that is what my dad uses in his Harley and other friends use as well. Is my GS, a 2002, designed for a specific grade (such as certain cars are)?

Thanks,
Tom

[fraze11]

I use good 'ol regular unleaded.  My owners manual say's to use regular 87 and thats fine with me, its the cheapest too 

Note: my bikes not modified engine wise at all so I dont know if pipes, filters, jets etc etc require something more.

[Porkchop]

Is my GS, a 2002, designed for a specific grade (such as certain cars are)?

Yes, regular unleaded 87 octane.

- Porkchop

[shchuka]

Interesting... In UK there are normally 2 grades of petrol: "standard" and "super" - with RON of 95 and 98 respectively.  I use standard (RON 95) in my GS - and as it is, with about 50/50 freeway/city mileage I get about 53-55 MPG.

I use super (RON 98) in my car - and get about 60 miles per tank extra mileage (which equates to about 4-5 MPG difference). I keep wanting - but never do - try "super" in my GS, as it's just so bloody expensive!

[offcamber]

I been using Mobil 93 Octane...mainly because it has the additive to help clean the carbs. It really does work as I use it in my boat and it has helped performance especially since it sits 8 months out of the year. I don't think I get any better HP or economy with the 93 but since I am only putting a couple of gallons in at a time the price difference is negligible. I'm sure my GS would run fine on 87.

[JEREMY JOCK]

I always ran 92 or 93, depending on what was available wherever I was. But, I'm sure it would have ran fine on 87.

[gsJack]

I had four Hondas before my two GS500s that were made to run on regular gas and I ran 20W-50 oil in them summers after they had some miles on them.  All four progressed from regular to mid grade to premium gas to eliminate heavy gas knock under acceleration in the summer as they became carboned up over the years.  I ran 15W-50 Mobil 1 synthetic in my 97 GS500E for 50k miles and it progressed to premium the same way the Hondas did.  After 50k miles when the oil consumption increased considerably I switched to the 15W-40 heavy duty dino truck oils like Delvac, Rotella T, etc that were becoming popular with bikers and were much less expensive and it ran on regular gas without any further gas knock for the next 30k miles I used it.

My current 02 GS500 has only seen the 15W-40 oils and regular grade gas since I've had it and has yet to have any gas knock.  It had 4k miles on it when I bought it and just turned 80k miles last week and still runs like new.  Oil has two functions in an air cooled engine, to lubricate and to cool, and a lighter oil flows more freely and cools the head area better than a heavier one and it's the combination of high compression and engine heat that causes gas knock.  Your GS500 will run better on regular gas than on premium if it doesn't knock on regular.  Premium gas causes the fuel/air mix to burn slower to eliminate knock on higher compression engines.  The Rotella T 15W-40 dino juice now carries the JASO MA designation.

[Twism86]

My current 02 GS500 has only seen the 15W-40 oils and regular grade gas since I've had it and has yet to have any gas knock.  It had 4k miles on it when I bought it and just turned 80k miles last week and still runs like new.  Oil has two functions in an air cooled engine, to lubricate and to cool, and a lighter oil flows more freely and cools the head area better than a heavier one and it's the combination of high compression and engine heat that causes gas knock.  Your GS500 will run better on regular gas than on premium if it doesn't knock on regular.  Premium gas causes the fuel/air mix to burn slower to eliminate knock on higher compression engines.  The Rotella T 15W-40 dino juice now carries the JASO MA designation.

Why 15/40 instead of the specified 10/40? I dont think mine knocks, but most people cant really tell unless its horribly bad, you need a knock sensor.

[shchuka]

I been using Mobil 93 Octane...mainly because it has the additive to help clean the carbs. It really does work as I use it in my boat and it has helped performance especially since it sits 8 months out of the year. I don't think I get any better HP or economy with the 93 but since I am only putting a couple of gallons in at a time the price difference is negligible. I'm sure my GS would run fine on 87.

Well, the price of petrol (gas) in UK is a lot higher than on the other side of the pond (like about $6.50 per gallon for the cheaper version).  And, yes, you do put only a couple of gallons at a time - but how often?  A full tank lasts me three trips to work (about 200 miles total) and the difference in price would be about $2.50 per tank - that would add up to about $23 per month - not that negligible any more.

[Homer]

My contribution:

[the mole]

Interesting... In UK there are normally 2 grades of petrol: "standard" and "super" - with RON of 95 and 98 respectively.  I use standard (RON 95) in my GS - and as it is, with about 50/50 freeway/city mileage I get about 53-55 MPG.

I use super (RON 98) in my car - and get about 60 miles per tank extra mileage (which equates to about 4-5 MPG difference). I keep wanting - but never do - try "super" in my GS, as it's just so bloody expensive!

If your car has electronic engine management, it will "re-tune" itself to take advantage of the higher octane fuel and give better economy (and maybe power). The GS with its carbs won't know the difference so you'd be throwing money away if you use premium fuel.

[tykho]

Regular unleaded in Colorado is 85 octane lolz

[marcusk]

Now i will throw in my 2 cents here baeacse now i have ridden 150 Km i am an expert on all things bikes  .  I ran 95 in my bike when i rode it on the weekend and it ran well.  I use the 95 because its what i put in my car no other reason at all.

I did try 98 in my car but it made no difference over the 95.

People have a lot of theories on octane ratings in fuel but i don't think it will make a huge difference unless your machine is tuned for it.  with a higher octane fuel maybe you could run a little leaner???  if it makes the back wheel turn its doing its job providing a bit of fun for those fortunate enough to enjoy it.   

[kml.krk]

when I first got my GS I used 93 just because I was told it was better. Now I run 87 and the difference I see is: NONE.

[black and silver twin]

Contrary to popular belief, premium gas does NOT increase power, not directly any way. actually higher octane gas has less energy-per-unit-volume, 1 gal of 87 octane has more potential energy than 1 gal 93 octane (im using {ron+mon}/2 rating method, its the method used in USA). So in theory lower octane gas will yield more power and better mileage, this is true to an extent.

octane is the resistance to detonation, detonation is bad. you need enough octane to prevent detonation but not too much or you'll lose power/economy.

If the engine in question (gs500) has low compression (gs500 9:1 = low), low air flow (gs500 2valves-per-cylinder = low flow), and/or less timing advance (gs500 has 40* = less) it can run on lower octane just fine and will actually run better with it.

But if the engine (any modern super sport) has high compression (12:1 is common= high), high cylinder flow (4 valves per cylinder = high flow), and/or lots of timing advance (+50* = alot) 87 octane will just preignite and eventually destroy the motor. So in this engine you need higher octane which will allow you to extract more power via high compression ect. even though higher octane has less energy-per-unit-volume.

There are many other factors including heat and AFR but on a well functioning motor they shouldn't come in to play.

Basically a gs500 uses regular, higher octane wont hurt it but you will lose power and mpg (unless there is something wrong with the engine)

FYI even a gs500 running a 13:1 afr with +6* timing runs best on regular, I tested it on the dyno.

[mister]

What B&S twin said.

Generally, anything above 9:1 would benefit from higher octane - in theory. And 9:1 or below should see no difference. As the GS is 9:1, running either should be fine.

The difference I have noticed is within Shell, the brand. Shell regular and the bike sounds off and mileage goes down. Shell premium is a little better but the mileage is still down. But for mine, BP is where it's at. And I've noticed some gas stations having their regular as 10% ethanol - or an amount of ethanol added. I don't want to run ethanol. So I'll load up with mid grade premium - which in Oz is 95 (we have 91, 95 and 98 as our numbers refer to it - our 91 is the US 87).

Michael

[marcusk]

YOU'RE the second person that said that BP fuel is the winner in bikes Michael.  I will try that out next time I get Pet that should be in about a month at the rate the GS burns fuel and how much time I have ATM.  last weekend me and a mate went out he on his 98 R1 and me on the GS  I burned 8 liters and he doubled that. 

[Anderw]

Another UK member, I try and use 99RON, not sure how it works, but I found a link

Fuel
E10: 87-93 RON
regular gasoline in US and Canada: 87AKI 91-92RON
EuroPremium/UK Regular: 90-91AKI 95 RON
US/Canada/Australia Premium: 93AKI 97-98RON
SuperPlus in Germany and UK: 93-94AKI 98 RON
Shell V-power: 93-94AKI 98RON
BP Ultimate 102: 97-98AKI 102RON

So the cost per litre in the UK is equivalent to $1.76US [$1.80CAD] our gallon is different to your's as we use the metric system [ http://www.youtube.com/watch?v=srrsjDWCHTU ]!

I manage around 200 miles to 13 litres on my '08 GS500f

[Jeff P]

...and/or less timing advance (gs500 has 40* = less) it can run on lower octane just fine and will actually run better with it.

But if the engine (any modern super sport) has high compression (12:1 is common= high), high cylinder flow (4 valves per cylinder = high flow), and/or lots of timing advance (+50* = alot) ...

Anybody know what the timing on a Bob Broussard ignition advancer is? 

jeff

[Flanders]

black and silver twin knows what he's talking about 

You're pissing your money away if you're putting in gas with a higher octane value than what your engine is designed for. 

We've got "ultra 94" at sunoco stations here, and that's a marketing winner.  No car is programmed for 94 octane from the factory (91 is our standard high grade here), yet they manage to get folks to pay 5 cents more per liter for it!  Yes it's full of cleaners, but higher octane fuel burns 'dirtier' so it needs the extra cleaners to clean up after itself.