If you have huge carbon build up raising compression that could explain it...,
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Forum LongTimerGSResource Superstar
Past Site Supporter- Oct 2006
- 13999
- London, UK to Redondo Beach, California
I agree, 3 different GS bikes and none are any different on any grade of gas.
If you have huge carbon build up raising compression that could explain it...,1980 GS1000G - Sold
1978 GS1000E - Finished!
1980 GS550E - Fixed & given to a friend
1983 GS750ES Special - Sold
2009 KLR 650 - Sold - gone to TX!
1982 GS1100G - Rebuilt and finished. - Sold
2009 TE610 - Dual Sporting around dreaming of Dakar..... - FOR SALE!
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DanTheMan
87 octane. Out west I run 85 octane (lowest grade) except in the higher elevations and low desert with temps over 100 deg F because then it tends to ping. If I hear pinging (pre-detonation), it's time go up one grade.
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David_510
On my 83 gs550esd i've tested this theory actually...
Done it in my car and truck aswell..
On 87, 3.8 gallons of gas will get me 172~ miles
On 89, 3.7 gallons of gas gets me 188~ miles
On 91 3.8 gallons of gas gets me 214~ miles
So as you can see, my bike runs better on premium. It's not like there is a difference in the type of additives, it's the extra added octane.
This is the same for my car aswell (a 240sx 2jz motor) where i get about 8 mpg better (24mpg) running 91 over 87.
And same goes for my truck (03 dodge hemi) gets about 2 miles better off of 91 (13 mpg WHOOHOO!!)
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Forum LongTimerGSResource Superstar
Past Site Supporter
Super Site Supporter- Mar 2006
- 35712
- Torrance, CA
Originally posted by David_510 View PostOn my 83 gs550esd i've tested this theory actually...
Done it in my car and truck aswell..
On 87, 3.8 gallons of gas will get me 172~ miles
On 89, 3.7 gallons of gas gets me 188~ miles
On 91 3.8 gallons of gas gets me 214~ miles
So as you can see, my bike runs better on premium. It's not like there is a difference in the type of additives, it's the extra added octane.
This is the same for my car aswell (a 240sx 2jz motor) where i get about 8 mpg better (24mpg) running 91 over 87.
And same goes for my truck (03 dodge hemi) gets about 2 miles better off of 91 (13 mpg WHOOHOO!!)
I don't mean to sound argumentative but this information goes against logic.
Higher octane gasoline actually tends to burns slower, thus it resists detonation better. It does not have more energy per unit volume.
Engine designers can take advantage of higher octane fuels ability to resist detonation by increasing the engines compression ratio, or advance the ignition, both of which will extract more power out of the fuel and increase mpg. Modern engines typically have detonation sensors (called knock sensors) and automatically adjust the ignition timing to take advantage of high octane fuel. Some car manufacturers list two hp ratings for their engines: normal rating using regular fuel, and a high performance rating when using premium.
So if we run premium fuel in our GS without advancing the ignition timing (or the compression ratio) it's not logically possible to get more mpg from our engines. It could be that the particular brand of premium fuel you are using is has less alcohol than in the regular fuel, in which case your story would make since since alcohol is known to reduce mpg. I don't know but the octane alone can not do what you say.Last edited by Nessism; 05-10-2011, 06:47 PM.Ed
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Originally posted by Nessism View PostI don't mean to sound argumentative but this information goes against logic.
Higher octane gasoline actually tends to burns slower, thus it resists detonation better. It does not have more energy per unit volume.
Engine designers can take advantage of higher octane fuels ability to resist detonation by increasing the engines compression ratio, or advance the ignition, both of which will extract more power out of the fuel and increase mpg. Modern engines typically have detonation sensors (called knock sensors) and automatically adjust the ignition timing to take advantage of high octane fuel. Some car manufacturers list two hp ratings for their engines: normal rating using regular fuel, and a high performance rating when using premium.
So if we run premium fuel in our GS without advancing the ignition timing (or the compression ratio) it's not logically possible to get more mpg from our engines. It could be that the particular brand of premium fuel you are using is has less alcohol than in the regular fuel, in which case your story would make since since alcohol is known to reduce mpg. I don't know but the octane alone can not do what you say.
I agree with this.
I pretty much use nothing but regular unleaded, I have found that for some reason (I don't know why) that my vehicles get better gas mileage when I fill up with Shell gasoline as compared to Chevron and Texaco.
For example, my Nissan Titan truck using Chevron or Texaco I get consistently 11mpg normal city driving, but when I fill up with Shell my mileage is 15mpg and if I use Shell while on the highway I get 19-20mpg, not bad for a Titan. I tried it in my wifes Honda Civic with the same type results.
Just my .02 this is what I have found.http://www.visitedstatesmap.com/imag...TXUTWAWIsm.jpg
"Democracy is two wolves and a lamb voting on what to have for dinner. Liberty is a well armed lamb contesting the vote." Benjamin Franklin, 1759
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A very poorly tuned engine could run less badly on premium, say if the timing was far too advanced, slowing down the burn with the higher octane could result in better mileage. Or if it was lean and pinging slightly all the time, premium would make it less of a problem. More likely it's the alcohol content, even a small change in content makes a HUGE difference in mileage.
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I have been running premium in my GS1000G lately. I was a little afraid to, but it seems to be working fine.
It is left over from summer of 2006, I have been draining it from the tank of my old autocross car which I hope to have back on the road this week.
six year old premium rockssigpic Too old, too many bikes, too many cars, too many things
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Originally posted by 850 Combat View Post]... six year old premium rocks
.sigpic
mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
#1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
#2 son: 1980 GS1000G
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Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
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Originally posted by Nessism View PostEngine designers can take advantage of higher octane fuels ability to resist detonation by increasing the engines compression ratio, or advance the ignition, both of which will extract more power out of the fuel and increase mpg. ...
In reality, "premium" gas is a Band-Aid that allows the use of higher compression, which is what really makes the power. The added compression adds heat, which can ignite "regular" fuel before the spark lights it. "Premium" gas is harder to light, so it waits for the spark.
Because "premium" gas also burns slower, the ignition has to be advanced to light it sooner so it is completely done at the proper time. However, even when burned at the proper time, "premium" still contains fewer BTUs per gallon, so there is no more energy to be had by simply throwing some in the tank.
So, if you simply fill your tank with "premium", and your engine is working nearly perfect, you will see a small drop in power because the gas has less energy and it's not being burnt properly in the engine. Advancing the timing will at least get as much as you can out of it, but it's still less than "regular" gas.
If your engine seems to run better with "premium", it's possible that you have carbon deposits in the engine that are glowing a bit, lighting the "regular" gas, and the "premium" gas resisits that. Again, the "premium" gas is a Band-Aid to mask a problem that should really be fixed properly.sigpic
mine: 2000 Honda GoldWing GL1500SE and 1980 GS850G'K' "Junior"
hers: 1982 GS850GL - "Angel" and 1969 Suzuki T250 Scrambler
#1 son: 1986 Yamaha Venture Royale 1300 and 1982 GS650GL "Rat Bagger"
#2 son: 1980 GS1000G
Family Portrait
Siblings and Spouses
Mom's first ride
Want a copy of my valve adjust spreadsheet for your 2-valve per cylinder engine? Send me an e-mail request (not a PM)
(Click on my username in the upper-left corner for e-mail info.)
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radek22
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1_v8_merc
Just noticed guys....my 78 gs750 calls for at least 90 or 92 octane......
And the PO rebuilt the motor and re-grinded the cams for torque, and I don't know what else he did to the motor.
Should I keep running close to 90 octane?
I haven't had any pinging so far.
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Running my bike in high temperatures last summer, and at high altitudes, I found 92 or 93 kept the pinging away. I also found a gas station that sold ethanol free gas in premium only.
I don't see a problem with spending 20 cents a gallon for 4 gallons of better fuel. An additional 80 cents isn't a lot of money. I wouldn't fill a 20 gallon car tank with it, especially since cars have computerized fuel injection that compensates for the fuel. Alas, we don't have that luxury. Gas today is watered down with ethanol, toulene, xylanol, and a host of other additives which do who knows what.
I'm not telling anyone what to buy, and I get razzed for "wasting" premium fuel on my bike but I really don't care what others think or do. If they want to buy my gas then they can pick the grade.1981 GS650G , all the bike you need
1980 GS1000G Power corrupts, and absolute power corrupts absolutely
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7981GS
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