For those that advocate using 87 octane in these bikes

[tkent02]

And oil control. If any oil is getting in the chamber, you are effectively reducing the octane rating of the fuel.

Can you please explain this part? I can see it on a two stroke where too much oil mixed in the gas leans the mixture but on a four stroke?

[gmansyz]

tk
Sorry, but short of writing a book or an SAE paper, I'll try with a short answer.
These are two different conditions or applications.
The two stroker usually has maybe a 6 to 7:1 compression ration once the ports are closed. Maybe 7.5:1 max. When adding too much oil, you are reducing the gas. Hence the lean out. On a 4-stroke, the extra oil reduces the gasoline's octane. Making it more like diesel fuel and then uses a Cetane rating. Diesels have know naturally. Hence the heavy build. Though the Audi's are lighter designs and are even raced. But that is a different direction from this posting. So the extra oil reduces the fuels resistance to detonation and the "knocking" you hear. The pressure rise along with the heat causes the mixture at the ends of the chamber to "explode" on their own. The cause of the noise you hear. Running it rich is one way to cool the charge down so hopefully is doesn't get into the higher pressure that causes the noise.
Does it help?
Sorry for the poor explanations, it's just my problem with converting what I know into something easily read through writing.
Laters
G

[MisterCinders]

Where do you put the extra oil for a 4-stroker? My bike runs a touch rich, so maybe some more oil is the answer

[49er]

Where do you put the extra oil for a 4-stroker? My bike runs a touch rich, so maybe some more oil is the answer

Easy solution..........fit a a 2 stroke oil tank where your side covers used to live, and plumb the oil feed into your balance ports on the inlet tracts.

You'll now have a nice smokey 4 stroke that builds carbon in the chambers, fouls spark plugs, and still runs rich.

[themess]

... I got on board of unleaded train -- good stuff. do a lot with it.. alcohol fuel not so much.
...
we get different seasonal gasoline blends here on the Michigan lake shore counties of WI. I cannot tell you the actual difference BUT The stuff causes older pod/jet kit bike problems if they run 100% pump gas.....

IMO, ethanol from corn should only be used as a replacement for MEK, meaning an oxygenate to reduce summer ozone, and as an octane enhancer. As a replacement for gasoline, no way. Get some supercharged engine designed for ethanol from the get-go, and the it might be OK. For now we use E-10 because of the Iowa caucuses.

I won't say that all engines will run properly on E-10. My GT and GS were fine on it. Most GSR members who run stock GS engines, or nearly so have not had problems. I'd hate to mess around with the custom fuel blends that you describe.

[Katarat]

Spend the few cents extra, it doesn't make sense to me. I use non alcohol added fuel too, alcohol really does a number on the fuel system and carbs. Out here you have to buy premium to get the alcohol free gas

[duaneage]

My GS always pinged on 87 Octane. A real pain when riding in the boonies where the only grade available is 87. On 91 it was better, but stopped completely on 93. And it was 100% stock.

This is my experience as well. My 650 runs much better on 93 and I think 70 cents a tank is worth it for better gasoline.