Q about octane/no ethanol

[skids]

The Denver area sells "regular gas" as 85 octane. A spokesperson said on TV that because of the elevation performance is not compromised.

[JeffH]

The Denver area sells "regular gas" as 85 octane. A spokesperson said on TV that because of the elevation performance is not compromised.

yep,
......... and it sure ran great in my 11E.
I rode 1,400+ miles around Colorado exclusively on 85 Octane. Mostly Shell 85. XS11 ran great. Started great Cold & Hot.
Even to 14,110 ft on Pikes Peak. That 85 octane was perfect. Not one ping or knock. Got good MPG too.
No performance compromise either like that little romp on Hwy 9 back to Echo Canyon.

Jeff

[Bonz]

The Denver area sells "regular gas" as 85 octane. A spokesperson said on TV that because of the elevation performance is not compromised.

Yes, that is correct. With less oxygen in the atmosphere there is less ability to pre-ignite, thus they get away with selling 85 octane to us at a similar price to 87 octane elsewhere around the country. My ZRX has a one point compression bump over stock (11.0 vs 10.0) as well as a +4 ignition advancer and I still can run it on 85 octane at 7200'. In the past few weeks I found a new gas station with 87 octane 100% gas. So the past tank has had that in both the XS and the ZRX. My main interest is to see if I gain any mpg with 100% gas vs 90% gas-10% ethanol which has lower BTU's. The bikes have run fine on 10% ethanol for ages, so if there's no advantage in economy I'm not spending $0.40 more a gallon.

LOL JeffH, remember you're running at about 25 to 30% less air resistance in addition to the lower oxygen content in the air. I am convinced the better gas mileage many people get out here with their vehicles is a result of lower wind resistance verses anything to do with carburation or fuel injection.

[motoman]

......actually, seemingly running better is result of less vacuum draw. Remembering these scoots use vacuum slides that operate the needles, less vacuum equals less opening(raising) of the slides equals a bit less fuel allowed into venture. Horsepower loss though is definitely noticed with 3% loss of horsepower for every 1000ft. rise in elevation......which defintitey proves out correct for a few who have dyno-tested that theory with their Honda ST1100's in three different elevation locations.

[Bonz]

Don't understand the "running better because of less vacuum draw"? That seems to be saying at lower elevation the slides open further and therefore at wider open slides the bike doesn't run as well. What ever oxygen is available gets mixed with whatever fuel is available, and it runs like it runs.

My take on what is being said: To get the same power you'll need more throttle rotation at higher elevation. That can relate to a less touchy throttle vs sea level on a perfect day, which can feel more mellow and therefore feels like it "run's better". Elevation: It's like having a lower power engine map that a lot of fuel injected bikes have these days.

I drove the cage to Wichita Kansas over the weekend to see my daughter play in a MAYB basketball tournament. My wife's Nissan Rogue is the best Road car we have and holy balls that little 2.4 L four-cylinder felt like it added two extra jugs running around Wichita compared to running around 7200 feet of elevation.

[motoman]

Don't understand the "running better because of less vacuum draw"? That seems to be saying at lower elevation the slides open further and therefore at wider open slides the bike doesn't run as well. What ever oxygen is available gets mixed with whatever fuel is available, and it runs like it runs.

My take on what is being said: To get the same power you'll need more throttle rotation at higher elevation. That can relate to a less touchy throttle vs sea level on a perfect day, which can feel more mellow and therefore feels like it "run's better". Elevation: It's like having a lower power engine map that a lot of fuel injected bikes have these days.

I drove the cage to Wichita Kansas over the weekend to see my daughter play in a MAYB basketball tournament. My wife's Nissan Rogue is the best Road car we have and holy balls that little 2.4 L four-cylinder felt like it added two extra jugs running around Wichita compared to running around 7200 feet of elevation.

Sorry, shoulda' added economically following 'better'.

[Bonz]

OK, now you're talking. I read an article around 2011 from the Iron Butt riding group in relation to throttling losses. Deals with increasing MPG.

In essence it is saying by running a taller gear with more throttle opening we create less vacuum for the piston to suck against on the intake stroke thus reducing throttling loss. As well, a taller gear provides lower engine speed for any given road speed and lower friction with the engine at the reduced speed.

At any given road speed within normal parameters, the smallest carburetor/throttle body with the largest throttle opening that will allow any engine to maintain speed is ideally what we would want in a perfect world.

I have copied the link below. I think it makes infinite sense.

http://www.ironbutt.com/ibmagazine/ibmag6-p58-62.pdf

[speedlimit85]

I am reading that article.

I am getting an engine pinging from the 87 octane non-ethanol gas.

Therefore, I am going back to the 90 octane non-ethanol gas.

To the one who started this thread: I recommend non ethanol gas that is 90 or 91 octane.

[Bonz]

That is unique for any XS1100 to require 90 or 91 octane. That is definitely an exception rather than the rule. If his bike pings on 87 octane then I would recommend higher octane as well. He specifically said his bike runs fine on 87 octane ethanol. There is no need to run higher octane when that is the case. He was simply asking should he run higher octane non-ethanol versus lower octane ethanol even if his bike is running fine. Running higher octane on a continuos basis risks carboning up the exhaust valves. I don't know how many people that has happened to, however it is a reality of internal combustion. Therefore why do it?

[MPittma100]

Maybe

Each XS11 that I have ridden likes more than 87 octane. And responds favorably to E0 fuel. Engine performs better, gets better MPG, and there is no excessive carbon on the valves. If I run ethanol 87 octane, there is a joy so desirable exhaust odor.

That is unique for any XS1100 to require 90 or 91 octane. That is definitely an exception rather than the rule. If his bike pings on 87 octane then I would recommend higher octane as well. He specifically said his bike runs fine on 87 octane ethanol. There is no need to run higher octane when that is the case. He was simply asking should he run higher octane non-ethanol versus lower octane ethanol even if his bike is running fine. Running higher octane on a continuos basis risks carboning up the exhaust valves. I don't know how many people that has happened to, however it is a reality of internal combustion. Therefore why do it?

[MPittma100]

Octane

Whoops!

Meant to say "not so desirable odor from the exhaust". Or, smells bad. They like 90+ octane. There is no excessive carbon on the valves, plugs, or chambers. 87 octane and ethanol do not work for me at all. I must mention that the octane requirement stated on the decal for the 11s is 89.

[Bonz]

MPittma100, thanks for the info about the sticker from 1979 that recommends 89 octane. 9.0:1 compression isn't that high, and for my bike, heck, the 85 octane works great and is attested by others who ride in the Colorado Rally and run it in their bikes. At least one from out of state, and probably every one of the riders from the state.

Remember, the OP stated his bike runs fine on 87 octane 10% ethanol and was asking if going to 91 non ethanol would be of any benefit or detriment. Bike running fine, I stand by the idea there is no need for him to run higher octane, pure gas or otherwise.

I'm going to start a thread with a poll about octane and comments.

[Bergman16]

After all this great info--thanks!--I have decided that I'll run 87 in the bike and use an additive if not on every tank definitely when I know I won't be riding it for a few weeks or so, which happens a lot, as I don't ride regularly here in NYC, I hightail it for one of the bridges to get out into the country or visit a friend upstate or down in Harrisburg. It seems like a good plan for a bike with intermittent use.

Steve

[Bonz]

When I rode the SG on Easter Sunday in mid-April, the gas in the tank had been there since early November with just 40-ish miles of riding. I used red Sta-Bil in the 10% ethanol 85 octane back in November.