Author Topic: Gas--Regular, Midgrade, or Premium  (Read 18766 times)

Offline billster

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Gas--Regular, Midgrade, or Premium
« Reply #15 on: September 09, 2005, 07:08:05 PM »
89
The older I get, the better I was.

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Offline Slider

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Gas--Regular, Midgrade, or Premium
« Reply #16 on: September 10, 2005, 01:30:34 AM »
87 is called "Regular" up here in Beaver Land. It seems to work fine in my  98  1200S Bandit. A couple of times the engine was quite crabby, (rough running), on a particular tank. I believe it was just a bad batch of fuel. As I understand it, using a higher grade than your owners manual calls for is a just a waste of money.

However. My manual calls for premium for its 9.5 compression ratio. Up here, the greedy oil companies demand 32 US cents a US gallon, 10Cdn  cents a litre Extra for premium fuel! ... and our government is greedier in fuel taxes and many other taxes.

A few days ago Regular was $1.35Cdn per litre  -the equivalent approx. of $4.35US per US gallon! :shock:

This is what led me to try "Regular" quite early. It worked as I haven't detected knocking.
Bandit 12, Yoshi can, jets, KNN, Gen Mar risers, 3 Givi 36L hardbags

Offline fake

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Gas--Regular, Midgrade, or Premium
« Reply #17 on: September 10, 2005, 01:40:15 PM »
Quote from: "Red01"
His gas has lower octane because he's at a higher altitude and you need less octane at higher altitude.


I'm only at 3200 feet...


Ya, it does suck for the vehicles that need 91+.  Guess you go to Wally World and buy octane booster. :wtf:
2005 B-1200S Limited

Offline Oldschooler

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Gas--Regular, Midgrade, or Premium
« Reply #18 on: September 10, 2005, 11:44:27 PM »
I have a B6 and I run Regular = 87 octane. I've been happy with it. My bike runs fine on it. I live in central Florida and drive half and half, stop-n-go and highway. The temps here get into the 98-99 degree range from July thru Sept.
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Offline techb

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Gas--Regular, Midgrade, or Premium
« Reply #19 on: September 10, 2005, 11:58:56 PM »
This is something on this topic I found on http://www.motorcycleperf.com
There is some other topics in there tech tips.

update on bad gasoline article

One of the most frequently encountered problems this season is the issue of “bad gas”.  While not involving flatulence, it just as big a problem.

We have had more fuel-related problems ranging from poor starting, hesitation, etc. to just plain “quit and won’t restart” this year than in any of the past 25 years we have been here.

A further explanation of the two different areas of concern with gasoline may be in order for those who wish to pursue it.  

1.) OCTANE  

This is the resistance to detonation the gasoline offers.  The most common grades of gasoline are:  REGULAR at 87 Octane;  MID-GRADE at 87-90 Octane;  PREMIUM at generally 93 Octane.  Other custom-built racing gasolines can offer up to 125 Octane.  Octane is an indicator of the speed at which the gasoline burns in the engine.

The higher the octane, the slower the speed of the burn; the lower the octane the faster the burn.  If the burn is too fast, uncontrolled combustion can occur.  This most often is heard as “pinging” and is commonly referred to as detonation.  This is because instead of burning through top dead center of the combustion stroke, the entire charge is ignited too early and explodes in the chamber and acts as a bomb.  Conversely, if the speed of the burn is too slow, it continues after the useful work can be done in the motor and manifests itself as poor throttle response, reduced power output and increased emissions and fuel consumption.  An engineering fact:  THE MOST HORSEPOWER IS MADE AT THE THRESHOLD OF DETONATION.  We have often gained horsepower on the dyno and felt improved starting and driveability going from Premium grade gas to Regular.  This change was recently quantified in a customer’s Ducati M900 by reducing the cranking time to start-up from 15 to 3 revolutions, although part of the improvement is explained below.

The multi-valve combustion chambers and their reduced flame front propagation distances in the modern engines virtually eliminates the need for high-octane gasoline.

2.) COMBUSTIBILITY

This is the ability of the gas to burn.  As mentioned above, gasoline needs to burn to be of any value in the motor.  Modern gasoline has been subject to formulation restrictions that now make it able to sit only 4 to 6 weeks after manufacture before its usefulness as a fuel is compromised due to reduced combustibility.  This is basically a separate issue from the speed of the burn as controlled by octane.

The biggest issue is the fact that the “volatiles” in this new formulation evaporate very quickly.

The reason these “volatiles” are so important is that they are the part of the gasoline that affects starting and throttle response.  That is why you can often feel the difference between individual tanks of gas when it comes to starting, cold running and acceleration at lower rpms.  The evaporation of these volatiles leaves a thicker, more viscous residue that becomes difficult for the carburetor to break up into combustible droplets.  This sludge will adhere to the intake runner walls or goo its way into the combustion chamber.

The poor burning characteristics can be seen in the accompanying photo.



This difference becomes more pronounced with carbureted bikes using a hemi-style engine design (Harleys, Viragos, BMW, Ducati, etc.) as opposed to 4-valve and/or fuel injected motors.

One of the recurring themes in these problems has been the use of Premium gasoline.

There are no 4-valves bikes made in the last 20 years that need premium gasoline for normal street use.  Very few of the 2-valve bikes need it either.  One of the problems with premium is the fact that it is not used as much and sits in the ground much longer than the other grades, with the attending evaporation of the volatiles present at manufacture.   This coupled with the more efficient combustion chambers used today makes the problem even worse.  A second issue is the different ways used to achieve that higher octane.  Each company has a different formulation, and with the high horsepower to displacement ratios of the newer bikes, tuning for this can be an issue.

A good rule of thumb is if the bike doesn’t ping and runs acceptably with regular, DON’T use Premium.  Regular is sold faster, is fresher and will generally start easier and have better throttle response than the higher octane gasolines.  Not nearly as many cars use premium as they can compensate for the lower octane of regular with built-in detonation sensors to compensate for the octane, thus reducing the amount of premium sold.  Most underground tanks hold in excess of 4,000 gallons of gas, so with primarily motorcyclists buying it three or four gallons at a time, it will be there quite awhile.  Also as the level in the tank drops it affords more opportunity for the volatiles to evaporate.  It doesn’t matter what the owner’s manual or your friends say.  We have often GAINED horsepower on the dyno when we took away octane.

We have had to make arrangements to properly dispose of all the gas that makes a bike run terribly, but works fine in a car or truck.  So try a tankful or two of regular and see how the starting and performance changes.  If the bike is unhappy, go back to what you were using before, but bear in mind the information here and be ready to switch if things change.

A good way to avoid problems such as this is to be certain you buy gasoline at a name-brand station.  The neighborhood   convenience store buys gas from a broker, so you have no idea what it is.  That gasoline is purchased by price, not specification. Also do not use ethanol-dosed gasoline, as it can be very reactive with the metal used in carburetor bodies.  Brand name stations have much more control over the product they sell.  We use Amoco Regular as our baseline gasoline in the shop due to convenience, but occasionally make the trip to Shell for what a lot of our customers have said gave the best results in their bikes, especially the twins.  Sealed containers of VP gasoline (some costing $42 per gallon) is another alternative, although cost prohibitive.

      Remember- always buy brand name fuels to reduce the potential entertainment that accompanies poor quality gasoline.

Offline LowRyter

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Gas--Regular, Midgrade, or Premium
« Reply #20 on: September 11, 2005, 03:12:30 AM »
even with an advancer, jet kit & slip-on, 87 is fine, even in 100 degree summers in Okla CIty...I use 86 in the mountains....the only time I ever had problems was in hot muggy traffic at Daytona and it was pinging pretty bad, I did switch to premium.....
John L

1998 Red Suzuki GSF-1200S
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Offline PaulVS

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« Reply #21 on: September 11, 2005, 12:11:55 PM »
Quote from: "techb"
A good rule of thumb is if the bike doesn’t ping and runs acceptably with regular, DON’T use Premium.  Regular is sold faster, is fresher and will generally start easier and have better throttle response than the higher octane gasolines.  

We use Amoco Regular as our baseline gasoline in the shop due to convenience, but occasionally make the trip to Shell for what a lot of our customers have said gave the best results in their bikes, especially the twins.


My sentiments EXACTLY.  I use Amoco (BP) or Shell regular only... unless I'm stuck where I can't get it.

(FWIW... I've found Mobil gas is the worst, in my bike and cars, which is odd considering I'm completely sold on Mobil1 oil.)


Offline Red01

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Gas--Regular, Midgrade, or Premium
« Reply #22 on: September 11, 2005, 03:36:48 PM »
Quote from: "PaulVS"
(FWIW... I've found Mobil gas is the worst, in my bike and cars, which is odd considering I'm completely sold on Mobil1 oil.)


That IS odd considering Mobil is owned by BP.
We don't even have Mobil stations around here anymore, they all changed to BP years ago.
Paul
2001 GSF1200S
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2010 Concours 14ABS
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Offline B12Teuton

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« Reply #23 on: September 11, 2005, 03:48:53 PM »
Quote from: "LowRyter"
even with an advancer, jet kit & slip-on, 87 is fine, even in 100 degree summers in Okla CIty...I use 86 in the mountains....the only time I ever had problems was in hot muggy traffic at Daytona and it was pinging pretty bad, I did switch to premium.....


The problem with what you say here is that "pinging" is usually only audible and problematic under heavy load/throttle.  If you heard it in traffic at Daytona where you were presumably just cruising around I'd be pretty damn concerned!   :shock:
 
Unless you have some phenomenal hearing, I have a hard time with anyone hearing pinging on a bike with a slip-on and wind noise to boot.  I was barely able to hear it on my bike when it was still stock, and then only under the following conditions:
~warm weather
~3-4th gear
~full throttle roll on @ 2-4000rpm
~leaning off the bike with my ear near the valve cover

It always did it with regular of any brand and didn't with mid-grade of any brand.  This was sufficient and there was no need to switch to premium.

Although many Bandits may run fine on regular, bikes vary and people's ability to pick up on issues like pinging vary even more.
A bike that was not broken in properly or has tons of miles on it may very well have .5:1 lower compression and that IMO is enough to prevent pinging on regular.
Manny
ATGATT (all the gear all the time!)
2006 KTM450XC Thump-whore

Offline Red01

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« Reply #24 on: September 11, 2005, 04:03:52 PM »
Quote from: "B12Teuton"
A bike that was not broken in properly or has tons of miles on it may very well have .5:1 lower compression and that IMO is enough to prevent pinging on regular.


Likewise, that bike may have higher compression from carbon buildup and require a higher octane. The other bad thing about carbon buildup is the carbon can get hot enough to glow and cause preignition from the hot carbon setting of the fuel mixture.
Paul
2001 GSF1200S
(04/2001-03/2012)
2010 Concours 14ABS
(07/2010-current)


Offline B12Teuton

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« Reply #25 on: September 11, 2005, 04:04:20 PM »
Quote from: "techb"
An engineering fact:  THE MOST HORSEPOWER IS MADE AT THE THRESHOLD OF DETONATION.


Then why is ignition always before top dead center?

Quote
When the compressed mixture inside a cylinder is ignited it takes time for the flame front to reach the piston and for the expanding gases to start pushing it down. The time that this takes changes according to a number of variables such as mixture strength, how well the cylinder has filled (dependent on volumetric efficiency and throttle opening), compression ratio and combustion chamber shape. Given the same circumstances of mixture strength, cylinder filling and CR, the time taken for the mixture to fully ignite and burn is the same regardless of engine speed. At increasingly higher RPM however, the time available for this burn to take place is correspondingly less, so it follows that you have to start burning the mixture earlier in order for it to push on the piston at the right time. This is the basis for increasing ignition advance.

Too much of this and the burning mixture hits the piston as it rises (pinking or pinging), too little and the flame front reaches the piston far too late and does not do a good job of pushing the piston down and the engine behaves like a herd of turtles. One of the reasons a diesel engine does not perform at higher RPM is that it has compression only ignition, so there is no way to increase the effective ignition advance.


So the engineering "fact" clearly does not apply to gas internal combustion engines.  It's also a good example of why I never got the 5* advancer.  It's not what you want for a torque happy street bike, though I'm sure it's great for a race/drag bike that spends it's life near redline.
Manny
ATGATT (all the gear all the time!)
2006 KTM450XC Thump-whore

Offline Red01

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« Reply #26 on: September 11, 2005, 04:18:57 PM »
Manny, that would be exactly why you would have spark before TDC.

It's not ALWAYS before TDC... I had two Audis that fired 3* after.
They both used the same engine found in Rabbits, Golfs & Dashers.
(OTOH, it was a common hop-up trick to advance their timing 10*)
Paul
2001 GSF1200S
(04/2001-03/2012)
2010 Concours 14ABS
(07/2010-current)


Offline B12Teuton

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« Reply #27 on: September 11, 2005, 04:22:41 PM »
Quote from: "Red01"
Manny, that would be exactly why you would have spark before TDC.

It's not ALWAYS before TDC... I had two Audis that fired 3* after.
They both used the same engine found in Rabbits, Golfs & Dashers.
(OTOH, it was a common hop-up trick to advance their timing 10*)


But it suggests you should have 0* timing, doesn't it?
Manny
ATGATT (all the gear all the time!)
2006 KTM450XC Thump-whore

Offline B12Teuton

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« Reply #28 on: September 11, 2005, 04:25:16 PM »
Quote from: "Red01"
The other bad thing about carbon buildup is the carbon can get hot enough to glow and cause preignition from the hot carbon setting of the fuel mixture.


Not to mention reducing displacement if the carbon is on the piston :lol:

OK, enough of this... I gotta get back to painting the house :sad:
Manny
ATGATT (all the gear all the time!)
2006 KTM450XC Thump-whore

Offline Wayina

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« Reply #29 on: September 11, 2005, 09:14:16 PM »
I run (for the first 1200Klms, cause thats all I've done so far) Caltex Vortex pulp, currently $1.32 per litre and falling, 1200 hasn't missed a beat since I got it :bigok:
2005 GSF 1200S K5
Wayne in Sunny Brisbane (well mostly)