Astro again! 3rd post this week, I am coming up with more questions as I ride around and wonder what strange secrets the beautiful orange chunk of metal between my legs holds...

What fuel grade do you guys use? The bike takes 91 I believe, based off of the handy dandy tag under the seat. But most stations around me carry 87, 89, and 93. I've been using 93 but good lord, it's getting rather expensive. I mean, yea it's only 4 gallons or so but still! That adds up! Is 87 fine? 89? 99? Please, do tell!

Also, does anyone else's Res setting on the petcock not work at actual reservoir levels?

Re: RES, it may be a good idea to check if the hoses are routed properly.  If the lines coming from the tank to the petcock are switched then ON will actually be RES.
Otherwise it could be the screen inside the tank is fouled.  Might want to take the tank off and clean it out before your next fill up.


Re: Octane levels. I could swear the manual called for 87 octane, but I could be mistaken.
My Ducati calls for "premium" and that's what it gets (can't remember if it wants 91 or 93, I had to convert from the manual specification in RON to whatever the US uses.)
My Cherokee would take about $65 a week in regular gas, a tank of 91/93 for my Duc is $10 and I can typically get two weeks out of it.  Peanuts.

The GS isn't a performance machine and doesn't have high compression.  I think you'll be fine with just regular unleaded.
That being said, the difference in cost per tank is probably something like $1.  At that cost why not just use premium?

Hiya Astro!

I agree about the fuel hose routing. I've never had issues with using my Reserve. I normally run the bike until I feel it start to run outta gas, reach behind my knee and switch to RES. Then if I hafta go home for whatever reason, I do and leave a note on my bike to fill up next time heading out... otherwise I just head to the nearest gas station right then.

Check out this link for the corrected diagrams (the ones on parts sites and in the books are wrong, believe it or not!)
http://wiki.gstwins.com/index.php?n=Main.HoseRouting

Also, I've always ran with 87 in my GS. IIRC, Watcher is correct about the Owner's Manual recommending 87.

Now I will say this, I've always been the type to give my bike a bit more TLC than necessary (my last year's oil and filter change with Suzuki Ecstar comes to mind lol ) ...so if you live in a place where the difference in price from 87 to 91/93 isn't that much, then I say go for the premium!

what country are you in?  Different countries use different octane scales.  You can't compare say USA to Australia.

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

there's RON, MON, and AKI...just to add confusion to the topic!!!


Cookie

Quote from: AstroPenguin on May 22, 2018, 08:42:55 PM
Astro again! 3rd post this week, I am coming up with more questions as I ride around and wonder what strange secrets the beautiful orange chunk of metal between my legs holds...

What fuel grade do you guys use? The bike takes 91 I believe, based off of the handy dandy tag under the seat. But most stations around me carry 87, 89, and 93. I've been using 93 but good lord, it's getting rather expensive. I mean, yea it's only 4 gallons or so but still! That adds up! Is 87 fine? 89? 99? Please, do tell!

Also, does anyone else's Res setting on the petcock not work at actual reservoir levels?

Quote from: twocool on May 23, 2018, 04:31:52 AM
what country are you in?  Different countries use different octane scales.  You can't compare say USA to Australia.

IIRC he's from Ohio, the "good morning" state! (sorry, been watching too much anime lately).

The sticker on my gs says 91 RON iirc. USA rating is (R+M)/2 so who knows what the RON is but I've never had pinging with 87.

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You nailed it, I'm from Ohio! So USA ratings. Ok, good to know! The difference comes out to about 2 bucks a tank which isn't a lot, I know, but I just left my job and am going into thrifty mode. So every 2 bucks counts!

As for the petcock, I SWEAR I routed that right, I used those diagrams. And when I opened up my tank when it was sputtering, I still had fuel in there. So "On" didn't empty me out, so I don't think I switched them. But I'll double check!

Plus I only got like 130 miles out of it. Which is low, right? I wonder if I'm running rich....

US doesn't use RON. 91 RON is the lowest usual octane rating in countries using RON. ( 91,94(special ethanol),95 and 98( really for ultra high compression and turbo/supercharged motors). There is also 100 not from ther pump, often straight methyl benzene.
Either way the GS is a relatively low compression motor for a motorcycle and lowest will do. Alcohol fuels aren't a great idea with ordinary carb engines as ethanol reacts with the brass in the carby.
Using higher than design will NOT give you more power and can give you lass. The higher octane fuels are that way because they require more activation energy to fire. In a low(ish) compression motor such as this with ordinary coil ignition don't waste you money on bigger number fuel. NOTE: the later GS's use a multifiring spark and will burn more of the higher octane fuel, so will run OK if you don't have a choice.
One thing though. Conventional wisdom is that the higher octane fuel is cleaner and more consistant rate. Never seen anything to bear this out though.

Quote from: AstroPenguin on May 23, 2018, 12:56:03 PM
And when I opened up my tank when it was sputtering, I still had fuel in there. So "On" didn't empty me out

"On" won't empty ya out... I'd imagine running the bike on Reserve until it dies would get almost all the fuel outta the tank but I've never personally done it so I can't confirm.

What year GS do you have? Mine's a '98 so it has the smaller/earlier style tank, and I get around 120 miles on the tank before switching to Reserve. I don't do a lot of highway miles, just around town and to work and back, etc.

Fuel tank capacities (gallons), copied from the wiki:

"California, pre-2000: 4.0 total, 0.9 reserve
Non-CA, pre-2000: 4.3 total, 0.9 reserve
California, 2001+: 5.0 total, 1.0 reserve
Non-CA, 2001+: 5.3 total, 1.0 reserve"

I am able to get non-ethanol "regular" 87 octane...so I use this in all my bikes.  I bring home 15 gallons at a time and feed off of that. That dealer also has 91 octane, but I don't go for that.  Another station I go to occasionally has only "premium" non ethanol  (90 or 91) so I get that if I'm there.  usually just a fill up or top off.


Cookie

Quote from: gregjet on May 23, 2018, 01:10:06 PM
US doesn't use RON. 91 RON is the lowest usual octane rating in countries using RON. ( 91,94(special ethanol),95 and 98( really for ultra high compression and turbo/supercharged motors). There is also 100 not from ther pump, often straight methyl benzene.
Either way the GS is a relatively low compression motor for a motorcycle and lowest will do. Alcohol fuels aren't a great idea with ordinary carb engines as ethanol reacts with the brass in the carby.
Using higher than design will NOT give you more power and can give you lass. The higher octane fuels are that way because they require more activation energy to fire. In a low(ish) compression motor such as this with ordinary coil ignition don't waste you money on bigger number fuel. NOTE: the later GS's use a multifiring spark and will burn more of the higher octane fuel, so will run OK if you don't have a choice.
One thing though. Conventional wisdom is that the higher octane fuel is cleaner and more consistant rate. Never seen anything to bear this out though.

In NY state, "Stewarts Shops" have 91 octane non ethanol

In PA I go to a station which specializes in racing fuels, but they ave non ethanol regular form the pump.

Cookie

Quote from: twocool on May 23, 2018, 02:48:07 PM
I am able to get non-ethanol "regular" 87 octane...so I use this in all my bikes.  I bring home 15 gallons at a time and feed off of that. That dealer also has 91 octane, but I don't go for that.  Another station I go to occasionally has only "premium" non ethanol  (90 or 91) so I get that if I'm there.  usually just a fill up or top off.


Cookie

Quote from: gregjet on May 23, 2018, 01:10:06 PM
US doesn't use RON. 91 RON is the lowest usual octane rating in countries using RON. ( 91,94(special ethanol),95 and 98( really for ultra high compression and turbo/supercharged motors). There is also 100 not from ther pump, often straight methyl benzene.
Either way the GS is a relatively low compression motor for a motorcycle and lowest will do. Alcohol fuels aren't a great idea with ordinary carb engines as ethanol reacts with the brass in the carby.
Using higher than design will NOT give you more power and can give you lass. The higher octane fuels are that way because they require more activation energy to fire. In a low(ish) compression motor such as this with ordinary coil ignition don't waste you money on bigger number fuel. NOTE: the later GS's use a multifiring spark and will burn more of the higher octane fuel, so will run OK if you don't have a choice.
One thing though. Conventional wisdom is that the higher octane fuel is cleaner and more consistant rate. Never seen anything to bear this out though.

91 in Australia is 87 in the States. Unleaded ethanol, steer clear of alcohol, including in the petrol. I've heard a tank of premium fuel every once in a long while may assist in cleaning the valve due to higher quality additives used in the more expensive fuels. Try to buy from large places with good turnover.

Nearly impossible to find ethanol free gas around here. I think the problems of ethanol in low concentration are overstated.

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I have a 1994, so I guess the smaller tank? What is the expected amount of miles to get from a fillup then? I sputtered at 130 miles of street riding, and then went to Res (granted that didn't work but whatever).

As for ethanol free, the nearest station to me that sells it is like 30 minutes away. So I honestly don't bother with it - it's just not available readily.

Yes, 1994 is the smaller tank. 130 from a full tank down to Reserve sounds good to me!

  empty you will still have fuel in tank. Its gravity fed. I always ran mine on reserve. And zeroed trip odo at fillups. Using 87. Around 120 miles iirc id be looking for gas.
Aaron

Quote from: mr72 on May 23, 2018, 06:07:40 PM
Nearly impossible to find ethanol free gas around here. I think the problems of ethanol in low concentration are overstated.

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I doubt that any place in TX is going to have ethanol free gas even if they advertise it as such.  As pointed out by Ed Wallace on inside automotive the distributors will put it in anyway if they have to get rid of the supplies on hand and nobody will know.   

There is at least one QT in Dallas that is already selling 15% ethanol....

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Well shoot, I was expecting to get like 200 a tank for some reason. Road trips just got that much more annoying! So if it's a 4 gallon tank, 130 miles - 30ish mpgs? I thought the GS got like 50mpgs. I guess my Passat gets the same fuel efficiency as the bike, wow!

130 miles on 4 (3.7l) gallons seems a bit low? I was getting ~60mpg (4.45l gallons) out of mine on a mixture of roads making circa 180 miles before reserve and maybe 220 miles range? And that was not a bike in good condition.

But even 60 is pretty dismal these days, I can get 60mpg out of a modern vw-group petrol. with AC. A 3cyl derv might get closer to 80 whilst not being absolutely horrible to spend time in.

but you have to sit in traffic jams. and there is loads more to go wrong. and cambelts.

Quote from: AstroPenguin on May 24, 2018, 02:01:13 PM
Well shoot, I was expecting to get like 200 a tank for some reason. Road trips just got that much more annoying! So if it’s a 4 gallon tank, 130 miles - 30ish mpgs? I thought the GS got like 50mpgs. I guess my Passat gets the same fuel efficiency as the bike, wow!

Don't forget, the reserve holds about a gallon.  So if it's 130 to reserve then that's about 40mpg and pretty typical for a naked motorcycle.  You can stretch it with proper tire pressure, some wind protection, and behaving yourself when it comes to the throttle, but 40-50 is pretty typical for... pretty much all motorcycles, truth be told.

My GSs got around 40-45 mpg.  My Honda CB500F got about 40-45 mpg.  My 1203cc Buell XB12SS got about 40-45 mpg.  My Ducati Monster 750 gets - you guessed it - 40-45 mpg...

I think mr72 had a sciency kind of reason for that.  IIRC it's something like "most motorcycles are about the same weight and about the same wind resistance, so at any given speed the amount of fuel needed to maintain speed is the same regardless of displacement" or something.  Where you'll GAIN gas mileage is losing weight and better aerodynamics.  Where you'll LOSE mileage (aside from an improper tune) is a whiskey throttle.