87 Octane, ethanol, and fuel additives

[krypto35]

Please share everything you know about fuel regarding GS500s - I started the post for "share your fuel mileage" and questions have begun to arise about whether higher octane fuel does anything for the performance of a GS.

Also, share your experiences/knowledge with fuel additives such as Sea Foam and Chevron - I have used both in my vehicles and gained some noticeable benefits = cleaner valves, better emissions numbers, etc.

[NiceGuysFinishLast]

Putting anything higher than 87 octane in the bike is just wasting money. Octane does not equal more power. Octane is a measure of resistance to detonation. Since the GS is NOT a high compression engine (comparatively), it does not require high octane fuel.

[ducati_nolan]

Yeah, you don't gain anything from the higher octane unless you up your compression ratio, or put a turbo on it. One exception may be if you're spending lots of time stuck in traffic in the summer, when the engine gets really hot, it's more likely to detonate/ pre-ignite. If that's happening you know you're too hot.

As far as the additives, every once in a while I'll use some Sea-Foam and it seems to clean the intake ports and the spark plugs, so I would assume that it's cleaning the rest of the combustion changer as well. I use the spray type and spray it through the carbs while reving it up. Haven't just poured the stuff in the tank yet but I bet it would work just fine too.

[makenzie71]

Putting anything higher than 87 octane in the bike is just wasting money.

Untrue...or not so much untrue as unclear.  You only need to run fuel that prevents knocking/pinging.  If the bike isn't knocking or pinging, running a higher grade is wasting money.

As said, octane is not power.  Compression is power.  Boost is power.  Etc.  Octane is just the rubberbands that holds the other crap together.

[Jughead]

Marvel Mystery oil does a really good Job in both the Tank and the Oil too.

[nArKeD]

I run 89 because the engine sounds smoother and pulls more evenly.  When I ran 87 it would occasionally make confidence draining noises and have some weak spots below 6K.  My bike has the K&N, V&H, and rejet though.  I run Chevron because there is a brand new station with modern pumps and the lowest prices in the area a mile away from my house.  Since Chevron doesn't even own a refinery in Washington state (and there are only a couple) I can't imagine the gas is meaningfully different from the stuff at any other stations.  A gas station with high turnover would likely be the most important criteria.  Fresh gas is better gas.

[manofthefield]

I've run both E10 (10% ethanol) and non ethanol gas in my bike and never noticed the difference.  Rema1000 runs E85 in his GS, but it requires much bigger jets in the carbs to prevent running too lean.  His exhaust smells like rubbing alcohol

[LMT]

I read all the posts and understand them but wonder why this 125cc scooter I have recommends 91+ octane?  I have a GS500F and Katana 600 and, as posted, they both run fine on 87.  I tried 87 in this scooter and it still seems to run just the same.

[LMT]

Please share everything you know about fuel regarding GS500s - I started the post for "share your fuel mileage" and questions have begun to arise about whether higher octane fuel does anything for the performance of a GS.

Also, share your experiences/knowledge with fuel additives such as Sea Foam and Chevron - I have used both in my vehicles and gained some noticeable benefits = cleaner valves, better emissions numbers, etc.

I used both Sea Foam and Chevron in an 03 Katana 600 I bought from Ebay.  Still ran like crap but I knew that at time of purchase (got a good deal on it so I bought it even at that).  It really only ran well after the carbs were dealer cleaned and synched.  I do believe that my opinion is that Chevron may be an edge better than Sea Foam based on all the research I could find about it.  But again nothing beats clean synched carbs.  Now that the carbs (4) are clean I do used Chevron periodically.  BTW I love the Katana!

[Egaeus]

I read all the posts and understand them but wonder why this 125cc scooter I have recommends 91+ octane?  I have a GS500F and Katana 600 and, as posted, they both run fine on 87.  I tried 87 in this scooter and it still seems to run just the same.

http://en.wikipedia.org/wiki/Octane_rating

Read the Measurement Methods section on the explanation.  In short 91 octane using the RON measurement is 87 octane using the (R+M)/2 measurement.  The US and Canada uses the Anti-Knock Index (R+M)/2 system (it even says so on those yellow stickers), while Europeans use the RON system. Most owner's manuals say to use at least 91 octane RON, even those for American cars, which leads to confusion and wasted money at the pump. 

[makenzie71]

Egaeus...he's in Ohio, not Canada...same octane system we all use.

LMT, the scooter requires a higher octane most likely because it has a very high compression ratio...a lot of road-scooters under 125cc have very high compression numbers.  The little 98cc scooter I had ran something like 14:1 or 15:1.

[Egaeus]

Egaeus...he's in Ohio, not Canada...same octane system we all use.

LMT, the scooter requires a higher octane most likely because it has a very high compression ratio...a lot of road-scooters under 125cc have very high compression numbers.  The little 98cc scooter I had ran something like 14:1 or 15:1.

Who said he was in Canada?

[makenzie71]

haha leave me alone...I just woke up...