intake and exhaust valves needed

[crazy steve]

Yep, not all gases are equal, and even the same brand/grade can vary depending on the area. Ethanol blends aren't seen too many places here because of the cold and humidity except in the counties that have air quality issues (which are generally the same ones that require emission testing). Around here, Arco has a terrible reputation (my wife let a friend fill her car at Arco, and she thought something was wrong with the car..), so we stick to Chevron, Texaco (same gas as Chevron) and Union 76 pretty much. I've never been impressed with Shell (years ago when I worked for Chevron, we had a Shell dealer as a customer at my station who wouldn't use his own gas!), and the other majors have very small presence here.

But buying a higher grade than you need is a waste; I noticed the same thing with my Sportster when I first got it; running premium made no difference in how it ran, cost more money, and I lost about 1 mpg.

Of course, after I jumped the compression ratio to 10.6:1, it's now a premium-only motor... it gets very unhappy on lower grades

[yamahaluke]

I have always ran pump, low octane and had no problem, on any motorcycle

[cywelchjr]

I remember not having much luck with Arco gas up there, and tending towards Chevron. Never have liked Shell for most cars, but have had one or two cars that loved it for some reason, my 89 Camaro comes to mind, for some reason that was the gas that it ran best on when it was on the road.

These days, most of my vehicles down here get Arco/AmPm Gas as it seems to do pretty well, and Chevron or 76 otherwise. And everything but the bike gets regular (the Camaro when running gets mid grade, but it's got a knock sensor and automatically adjusts the timing to take advantage of the octane) and the bike get mid grade (it really HATES premium, but likes mid grade the best) since it runs the best and gets the best mileage on that.

If it was real gas, I expect it would do best on regular, but with this mixed stuff, it needs the mid grade.

[Jarion]

Well,
The XS1100SG Owners manual - page 25 states that the recommended gasoline is "Regular gasoline" - my age immediately takes my mind to those days when I'd pull up to the gas pump and there would be a selection.... I could purchase "regular gasoline" or "unleaded gasoline".

I've spent an hour or so researching tonight and found that the "World" (different countries) introduced and switched to unleaded gasoline at different times in history... however, Japan apparently began in 1975 and totally switched by 1987.

It does make sense to me that Yamaha would have installed hardened seats in the heads in 1980 and.... (my interpretation follows)

Since -in 1980- they sold bikes around the globe and knowing that not all countries had introduced unleaded gas yet.... but knowing that their bikes would run on either a leaded or unleaded gas... they just decided not to specify either fuel in their owners manual (leaving it up to the owner to interpretate the term "regular").

I'm convinced
Another Beer Steve -
An you to CY -

http://www.chevron.com/products/prod...eaded_gas.aspx
http://www.unep.org/pcfv/pdf/VSR-FinalDraft.pdf

[Jarion]

And
This article says it all - it's one of the articles on XS11.

http://www.xs11.com/xs11-info/articl...arch-1980.html

Just under the first picture as you scroll through the article.

JT

[DCII]

It may not say anything in the owners manual about fuel requirements, however under the left hand side cover on both my 1980 SGs is the Yamaha Vehicle Emission Control Information sticker that lists Gasoline Grade: Regular (Leaded)
Research Octane: 91 Min. Personally I use mid-grade gas and will add a lead substitute additive every other tank full. I never gave any thought to whether the valve seats were hardened or not and hate to admit to it but have never checked my gas mileage.

[crazy steve]

...however under the left hand side cover on both my 1980 SGs is the Yamaha Vehicle Emission Control Information sticker that lists Gasoline Grade: Regular (Leaded).

He's right, it does say that. But still, I see this as a non-issue. Unleaded fuel has been gone for how long? 20 years? A looong time, and the number of reports of valve seat trouble on these bikes has been miniscule. Very few owners are bothering with lead substitutes for the good reason that they're not needed.

And this was never the 'big' problem that it was first made out to be; sure, some older motors had issues, but virtually all of them had integral seats in a cast iron head. The motors that had the vast majority of trouble were marine, farm, stationary equipment, and some old trucks; all applications where they were under substained high loads. Interestingly enough, aftermarket lead additives didn't prove to be very effective in these; I know the marine owners all ended up installing hardened seats...

[Jarion]

It is an interesting subject.... and one I muse over every time I'm at the gas pump..... and unscrewing the cap from my bottle of lead additive.