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Am I getting the gas I'm paying for?


beemerman2k

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beemerman2k

I'm about to embark on a reasonably long ride, and I have to cross the State of Connecticut. I never buy gas in Connecticut as it's more expensive than in any of the surrounding states, and they put some sort of MBTE additive in their gas that manufacturers warn drivers about not using gas so mixed.

 

So I'm in Massachusetts about to add about a gallon of Sunoco Ultra 93 to my K1300GT, and of course, this gas is very expensive compared to regular. So I pay the price for Ultra, pump about a gallon into my tank, and ride off wondering if all I just did was empty the lines of the cheap regular gas into my tank yet pay for Ultra 93!

 

How much gas gets pumped into our tanks from the previous transaction?

 

Assuming the prior user of the pump paid for regular gas, and you're now wanting Ultra 93, how much gas do you have to pump before you begin to actually get Ultra 93 as opposed to simply pumping the residual gas that was in the gas lines from the prior transaction?

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greiffster

I think there is about a 1/3 gallon in the hose, depending on the length. It's been discussed on other forums.

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beemerman2k

Occasionally I find a gas station that has a distinct hose for every grade, I love those places because now I know I'm getting what I paid for.

 

In all these hot temps I am riding in these days, this is a very important issue for the health of my engine; winter, not quite as much, I suppose.

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greiffster
Occasionally I find a gas station that has a distinct hose for every grade, I love those places because now I know I'm getting what I paid for.

 

Sure you are. ;)

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szurszewski

Think of the great service you're doing for the next guy who can only afford regular grade but is getting a 1/3 of a gallon of premium at a substantial discount!

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greiffster
Think of the great service you're doing for the next guy who can only afford regular grade but is getting a 1/3 of a gallon of premium at a substantial discount!

I suppose you could hang out at the gas station all day, following behind the turbo imports that require premium. Fill up the bike 1/3 gal. at a time, at the 87 octane price.

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szurszewski
Think of the great service you're doing for the next guy who can only afford regular grade but is getting a 1/3 of a gallon of premium at a substantial discount!

I suppose you could hang out at the gas station all day, following behind the turbo imports that require premium. Fill up the bike 1/3 gal. at a time, at the 87 octane price.

 

On a couple of occasions I've had someone on a moto come up, when I was fueling my bike, to ask if I was using premium, and then wait to use the same pump when I was done. Hadn't occurred to me to take this a step further- very creative thinking!

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Occasionally I find a gas station that has a distinct hose for every grade, I love those places because now I know I'm getting what I paid for.

 

In all these hot temps I am riding in these days, this is a very important issue for the health of my engine; winter, not quite as much, I suppose.

 

Afternoon beemerman2k

 

Not the end of the world (or end of you engine), your 1300GT has twin knock (ping) sensors so will back the spark advance off if lower fuel octane is used. You might be down a smidge on horsepower but shouldn't damage anything.

 

 

 

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I've never bought anything but regular. Never had a problem (or at least I've never had a problem that I could attribute to using lower grade gas. I got plenty other problems, brah). 1100RS. ymmv.

 

Have you thought about using an Oklahoma credit card? Shoot, at those prices, who cares what grade it is? Just don't grab some 2-cycle mix.

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I had a chem prof in school that was a motorhead and explained the "octane rating" of gasoline. Back then (The Dark Ages - or Good Ole days) it was an actual 1 cyl "proof" engine they ran batches of gas to see if they met the octane rating before "knocking". I understand today it is a much more accurate chemical analysis. Anyway, the cliff notes version of the "class" on octane is that the higher the octane the slower the burn. The opposite is also true: the lower the octane the faster the burn. And: the faster the burn the more energy is released. Bottom line: use the lowest octane rating your engine will burn without "knocking" or "pinging" for the best economy and mileage. The higher grades of gasoline have additives for cleaning (Techron, etc) and for increasing the octane rating (slowing the burn, i.e. iodine components now, used to be "ethyl" (and lead compounds which were outlawed).

 

Avgas (aviation gasoline, 100/130) is for engines with very high Compression Ratios. These are high output engines with a relatively low RPM (to keep the prop tip speed below the speed of sound). To get the output, they had to increase the CR which required a higher Octane gasoline (OR a gear reduction to the prop).

 

Like DirtRider said, these (most modern) engines have "knock" sensors to control the spark advance for the engine (plus conditions like the mixture of types of gasoline in the tank, altitude, temperature, carbon deposits in the combustion chamber, etc).

 

I don't worry much about the price, type, brand, or octane. My bikes burn them all. I prefer non-ethanol but ANY gas is better than no gas.

Edited by Lowndes
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beemerman2k
I've never bought anything but regular. Never had a problem (or at least I've never had a problem that I could attribute to using lower grade gas. I got plenty other problems, brah). 1100RS. ymmv.

 

Have you thought about using an Oklahoma credit card? Shoot, at those prices, who cares what grade it is? Just don't grab some 2-cycle mix.

 

 

When I rode my 2000 R1100RT, I'd put regular in the tank; not a particularly high compression engine. But now that I am on a K1300GT, it's premium only.

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I seldom buy less than 5 gallons at a time for my RT, which has a total capacity of about 7 gallons. Worst case, assuming an extra long pump hose retaining a half gallon of 87 octane before dispensing 93, I still end up with a tank of at least 92.5 octane gas.

 

I don't think I will be able to detect the performance difference, and I probably will not miss the 25 cents extra that I might have paid for un-delivered premium.

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aggieengineer

I don't think you need to worry about MTBE - Methyl Tertiary Butyl Ether. It was used as an oxygenate for years, but was abandoned when it began to show up in water supplies. Hence the move to ethanol. MTBE was actually harmless to your engine. In fact, the EAA (Experimental Aircraft Association) demonstrated running aircraft engines on pure MTBE. Ethanol presents is own set of problems, but is used nearly everywhere.

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When I rode my 2000 R1100RT, I'd put regular in the tank; not a particularly high compression engine. But now that I am on a K1300GT, it's premium only.

I normally use premium but several times have run into gas stations and/or towns that were out of premium. So a few times I have added half a tank of regular to the mix with no obvious consequences. The good news is that Mexico doesn't use ethanol, so I only get that on occasional trips to the US.

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beemerman2k

OK, theoretical question: like i said before, when i ride my mind wanders, and heres the latest it has conjured up.

 

Take a top shape, but stock K1300s. Fill it with good, high octane gas, send it off to do a quarter mile run. Lets say the rider manages a 10.00 second run.

 

Now, empty the tank and fill it with the cheapest US gas on the market, 87 octane, not much else.

 

What will thus rider net on his next quarter mile run all else being equal?

 

In other words, how much of an impact will the cheap gas have on performance?

 

 

Edited by beemerman2k
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chrisolson

The question really is how much will engine timing be reduced to eliminate detonation or pinging. That's where the horsepower is lost since as stated before, lower octane gas actually has more energy due to its faster burn. Kinda hard to evaluate without a dyno.

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Along the line of this thread, I was in Canada north of the Great Lakes. My partner and I were out of gas, low level lights were on. We stopped in a place to get gas but all it had was regular, 87 octane. Reluctantly I filled up. We motored on. I was anticipating some kind of reaction. Nothing. The bike never noticed. It never knocked, back fired or exhibited any symptom of the lower octane gasoline. At the next fill up I put in premium gas. It made me wonder about the whole octane thing. I still use premium in my bike, but now I don't worry if the station doesn't have any premium.

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OK, theoretical question: like i said before, when i ride my mind wanders, and heres the latest it has conjured up.

 

Take a top shape, but stock K1300s. Fill it with good, high octane gas, send it off to do a quarter mile run. Lets say the rider manages a 10.00 second run.

 

Now, empty the tank and fill it with the cheapest US gas on the market, 87 octane, not much else.

 

What will thus rider net on his next quarter mile run all else being equal?

 

In other words, how much of an impact will the cheap gas have on performance?

 

 

Evening beemerman2k

 

A BIG depends!

 

At sea level, 100°F+, probably a noticeable performance loss.

 

At 3500' above sea level & 65°F, probably not a lot of difference.

 

Running a 1/4 mile with a K1300 then regular might even be quicker as it might pull a little spark on the launch & get out of the hole better.

 

Octane rating has nothing to do with engine power, it is only the rating of the fuel's ability to resist knocking. Now how the engine management system

reacts to the lower octane fuel is where the power loss comes from.

 

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Running a 1/4 mile with a K1300 then regular might even be quicker as it might pull a little spark on the launch & get out of the hole better.

Sometimes your posts need a little translation. Do you mean that with lower octane gas, the engine management system might advance the spark timing to avoid knock and consequently the bike would get off the line faster. And if so, why would advancing the spark timing cause quicker acceleration from zero? That part is not obvious to me.

 

Edit: Advancing the spark provides more torque but less power?

Edited by Green RT
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Running a 1/4 mile with a K1300 then regular might even be quicker as it might pull a little spark on the launch & get out of the hole better.

Sometimes your posts need a little translation. Do you mean that with lower octane gas, the engine management system might advance the spark timing to avoid knock and consequently the bike would get off the line faster. And if so, why would advancing the spark timing cause quicker acceleration from zero? That part is not obvious to me.

 

Edit: Advancing the spark provides more torque but less power?

 

Afternoon Green RT

 

The engine management pulls (REMOVES) spark advance when it sees a knock signal from a knock sensor (it would never add spark advance as it can only remove advance).

 

With removed spark advance the engine will a be a little softer in it's power so reduced power at launce might eliminate some rear wheel spin tire slippage as the bike launches.

 

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beemerman2k

We used to have a member on this forum some time ago named, ShovelStrokeEd. He knows engine technology so well I wouldn't be surprised to get fairly exact answers to the impact of regular gas on 1/4 mile performance. Dude is an internal combustion nerd or geek, to use today's terms. A true motor head :thumbsup:

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