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Author Topic: Placebo or Real? 87 or 92 octane  (Read 1166 times)

Offline Rubo

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Placebo or Real? 87 or 92 octane
« on: August 19, 2017, 10:45:47 AM »
Hi guys
Lately I switched to 92 octane and my bikes 91NH runs smoother faster and seems to have more power.Noticed idle increased significantly and I adjusted back down but was puzzled why switching the octane increased the idle speed.
Anyway am I experiencing placebo effect or actually my bike runs better.I know it does but need your guys opinions

Offline ExTex

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Re: Placebo or Real? 87 or 92 octane
« Reply #1 on: August 19, 2017, 11:09:44 AM »
I would run some SeaFoam through the fuel system, (2 tanks of gas), using either gasoline, and then make the comparison again.


I think you got more Techron fuel system cleaner in the high octane gas and your bike had some deposits that got cleaned up.

Ride safely.
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Offline Larry Fine

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Re: Placebo or Real? 87 or 92 octane
« Reply #2 on: August 19, 2017, 01:19:13 PM »
I have used Amoco (now BP) premium (93 octane here) religiously in my bikes since the beginning ('72 CL450, '73 CB750K, '82 CB750SC, and current '96 750NH).  They all seemed to run better and cleaner, idle more smoothly, and accelerate better on it than anything else.

I rode year round on the '73 for three or four years (no car) and never even pulled the spark plugs once due to running issues.  When I finally did, they were clean enough to put back in.  The lightest gray color and no deposits.  I still find the same to be true with the '96 NH today.

I always have used premium because they're air-cooled engines, which run hotter than water-cooled engines do. The owner's manual recommends 87 octane if I remember correctly, but bikes get enough fuel economy that I don't worry about the cost difference like I do in cars.

YMMV (pun intended)

Offline Poligrafovich

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Re: Placebo or Real? 87 or 92 octane
« Reply #3 on: August 19, 2017, 06:44:31 PM »
Probably not the octane, but premium is sometimes different in other respects. Additives have been mentioned; another possibility is ethanol, or the absence of. Where I live some stations sell regular and mid grades cut with moonshine, and premium that's all gasoline.

Offline Captainkirk

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Re: Placebo or Real? 87 or 92 octane
« Reply #4 on: August 19, 2017, 08:34:33 PM »
Octane rating DOES have an effect on idle, anti-knock and performance. I used to have a practically unlimited source for obtaining 100 Low Lead Avgas and used to run it in the Nighthawk. Since switching back to 87 octane, the difference is quite noticeable...to the point where I am considering running premium in the Hawk regardless of cost.
Measure twice, cut once

Offline MrF

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Re: Placebo or Real? 87 or 92 octane
« Reply #5 on: August 20, 2017, 02:26:42 PM »
If the octane rating was the only difference, it has to be a placebo.  Like other folks have said, it's likely that the premium fuel is mixed with a better additive package that cleaned some gunk out.  It's also possible that it's not a 10% ethanol blend, which is hard to find these days.

Octane rating doesn't correlate to the specific energy of the gasoline or the performance you'll get out of it.  The octane rating is only a way of expressing how resistant the fuel blend is to pre-detonation.  What we see on the pumps here in the US is technically the Anti Knock Index (AKI).  If you look closely at the sticker, it actually has a formula on it: (R+M)/2.  AKI is the average of the research octane number (R), and the motor octane number (M).  The difference between the two is how the test motor is run.

Gas that's rated at 87 octane should resist detonation just like a mixture of 87% Octane and 13% Heptane.  (AVGas is measured differently, before someone brings up 110LL.) But no gas that you buy is just octane and heptane, it's a blend of a lot of different isomers and additives which is why you can't directly correlate Octane rating to how 'good' the gas is, just to how well it resists detonation.  In fact, in a pure Octane/Heptane blend, a lower octane rating equals greater energy content in the fuel since heptane has a higher specific energy than octane.

I think the misperception that a higher octane rating means a more powerful fuel is based on two things:  First, high performance cars tend to require higher octane gas.  This makes people think that it provides more power, when in reality the car just has a higher compression ratio.  The higher compression ratio requires a gas with higher detonation resistance, but also increases the efficiency of the Otto cycle to the point that a lower specific energy in the fuel doesn't matter.

Second, most modern cars that take mid grade or higher have a statement in the manual that you can use the next lower grade, but with a loss of power and performance.  This feeds the myth that higher octane gas is more powerful.  In reality, the motor uses knock sensors to retard the spark advance in order to use the lower octane gas.  The loss in power comes from the timing that gets pulled, because of the pre-detonation.  Not because the gas has less power.

Are you getting the gas from the same station?  I'd put money on a different additive package in their high-grade gas.  If it's a different station it could be top-tier vs bargain brand, or 10% ethanol vs not.
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Offline Rubo

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Re: Placebo or Real? 87 or 92 octane
« Reply #6 on: August 25, 2017, 09:58:56 AM »
Octane rating DOES have an effect on idle, anti-knock and performance. I used to have a practically unlimited source for obtaining 100 Low Lead Avgas and used to run it in the Nighthawk. Since switching back to 87 octane, the difference is quite noticeable...to the point where I am considering running premium in the Hawk regardless of cost.
I agree with you.Just did a 250mile round trip to Cape Cod and the bike run lot smoother and more power and I know its not placebo.
regards

Offline sgarnett

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Re: Placebo or Real? 87 or 92 octane
« Reply #7 on: August 25, 2017, 12:13:40 PM »
As mentioned earlier, there may be some difference due to ethanol content. Ethanol in the mix causes the engine to run leaner in an open loop (carb) system. Closed-loop control in a fuel-injected system can compensate for this; carbs cannot. That said, it's not a huge difference, but if the engine is a little lean already .... FWIW, stoich for gasoline is 14.7:1, while stoich for E10 is around 14.1:1

Higher octane fuel could conceivably burn at a different rate. Assuming (hypothetically) that it burns slower, that MIGHT improve idle and low-end torque. Whether there actually is a measurable difference, i have no idea. 

Offline Captainkirk

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Re: Placebo or Real? 87 or 92 octane
« Reply #8 on: August 25, 2017, 01:24:13 PM »
Higher octane fuel could conceivably burn at a different rate. Assuming (hypothetically) that it burns slower, that MIGHT improve idle and low-end torque. Whether there actually is a measurable difference, i have no idea.

On the dyno...can't say for sure. On the 'butt-dyno'...definitely! og2
Measure twice, cut once

Offline Jrrrrrrr

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Re: Placebo or Real? 87 or 92 octane
« Reply #9 on: August 26, 2017, 07:58:49 AM »
"Placebo" is the wrong term to be using here. This thread is looking for the term "confirmation bias."

That nitpick out of the way, I must not be attentive enough to notice any difference between 87-91 octane gas, as my NH doesn't seem to care.

What I have noticed is a difference in is winter-blend versus summer blend gasoline. The worst seems to be in CA where the winter-blend gas definitely results in a consistent highway MPG loss of 5-8. Refiners change up the hydrocarbon-cracking voodoo, resulting in more VOCs like butane, which evaporate easier. My hypothesis is that when the engine is hot, and especially when the gas tank is heatsoaked by a hot engine while the bike is parked, the increased VOCs in winter blend gas result in more of the gasoline vanishing into thin air.

Offline hppants

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Re: Placebo or Real? 87 or 92 octane
« Reply #10 on: August 26, 2017, 09:18:17 AM »
MrF and I are fishing in the same hole.  Scientifically and chemically, the higher octane (which is defined as the fuel's rate of burn) in of itself is useless for an internal combustion motor with compression and timing fixed to factory specifications to run on a lower octane fuel.  If we all assume that no one has altered the compression ratio of their nighthawk motor (shaving the head, using different pistons, and/or using a thinner head gasket), then the only way the change in octane (by itself) could be actually realized (conceived or not) would be if some extraneous factor was altering the timing on the motor, and thereby causing pre-ignition ping (knocking).  Understanding the concepts of the NH's ignition system - it's hard for me to fathom how that could happen.

That is it, and it's not debatable.

Now - do the additives make a difference?  I'm not sure.  Detergents, de-carbonizing agents, stabilizers, etc.????  There are way too many variables to make an educated opinion.  But my gut tells me that it's doubtful.

On the other hand, there is science that suggest that running higher octane fuel (which has a slower rate of burn) for extended periods of time on a motor that is NOT designed to run on that fuel, could INDEED cause motor damage.  If the fuel burns slower, it doesn't burn completely (or less completely) before it's pushed out of the exhaust valve.  Unburned fuel that is heated and cooled over and over again turns into a carbon deposit.  Heat treating that carbon deposit thousands (or millions) of times heat treats it and it becomes harder than the surrounding metal.  When those deposits form on the valve seats, over time, bad things can happen.

Now - fuel manufacturers use additives to counter the effect described above.  Techron is an excellent detergent to try and dissolve or dislodge those carbon deposits and send them to the catalytic converter or just out the pipe.  But either way, you are wasting money, IMO.

IMNSHO, running high octane fuel in a nighthawk is buying snake oil, plain and simple.

Offline DesertDragon

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Re: Placebo or Real? 87 or 92 octane
« Reply #11 on: August 26, 2017, 11:05:59 AM »
So, I've been following this thread for awhile, and I took a look under the seat of my 96 750.
The emissions sticker says use 91 or higher fuel (RON).
In the owners manual, it states that 86 octane should be used, but no rating designation is noted there.

I am assuming that this isn't a typo in one place or the other and the difference is because US pump octane ratings are (RON+MON)/2, and the RON number for the same fuel is higher than the previously noted "average" number because MON is a different (and lower) measure of the same gas.

I found an interesting explanation (to me, anyway) about the rating systems, and why premium fuel isn't necessarily better.
Here's that link http://www.thecarburetorshop.com/Octane.htm

For my local errands I travel the same route 3 or 4 days a week in a rural area with no traffic and no traffic lights, so I can make it the same trip.
Post office, store, back home, same speed, same gears, same drive.

I do a high speed run one day a week to blow out the carbon if I'm not going anywhere on the interstate that week.
The local town has two freeway entry and exits two miles apart on a deserted interstate (when I do it) which is perfect for a full bore throttle run... (What a great place to live (and ride!)

The bike gets a consistent 44 to 45 mpg when I fill it up, so I thought.. why not do an experiment, since most people cannot control the traffic, traffic light etc variables, I'm in a rather unique situation.

So,
I topped up with Mobil regular unleaded gas (which I always get) at the local station and refilled after 2 weeks.. 45.1 mpg.
No surprise. I always get very close to that for local travel, but just to establish the baseline...

On the next fill, (close to empty) I used Premium from the same station, ran the same routes and the same high speed runs.
Result - 50.4 mpg.
I was actually surprised at an unexpected (> 10%) improvement in mpg, but I have repeated the same test, and I get consistent results.

As far as performance is concerned, I did notice a difference.
My cold-blooded Honda took a lot less choke time.
On my high speed runs the bike ran noticeably better (again, a surprise) when close to red line (8500).

In my case, although my bike is 21 years old, it has low mileage, was babied like a child by all 3 owners and has new factory spec compression.
For me, the higher price of premium is a wash with regular gas because of the better mileage, but considering the bike runs better, I'm going to use super from now on until I see any change (especially in mpg).

Your results may vary, and like the link above indicates, if your vehicle doesn't need (or like it) it's a waste of money.
In some cases, there could even be some negative effects, especially in a compromised (low compression?) engine.





 

 
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DD

Offline Captainkirk

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Re: Placebo or Real? 87 or 92 octane
« Reply #12 on: August 26, 2017, 09:44:01 PM »
That is it, and it's not debatable.
How can you make a blanket statement like this when others have already posted their experiences which indicate improved fuel economy, faster warm up, increased idle speed and other improvements, real or perceived? Those improvements may or may not be worth the effort or extra money spent, but to dismiss them as "not debatable" is being closed-minded IMHO.
Measure twice, cut once

Offline Rakillia

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Re: Placebo or Real? 87 or 92 octane
« Reply #13 on: August 26, 2017, 11:29:23 PM »
I'm with pants on this one.  If you read everything he said, I agree with him.  If we are talking strictly about octane rating, no other variable, it can not make a difference.  If we include all the other variables, everything that every different company adds to the mix, its impossible to know what specifically is making the difference.  Since there is no way to remove all the additives, there is no way to prove that octane alone is making a difference when logically it can not.

Offline MrF

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Re: Placebo or Real? 87 or 92 octane
« Reply #14 on: August 27, 2017, 06:40:41 AM »
Rakilla and hppants said it more succinctly than I did.  I don't buy any of the subjective assessments, like "ran better", "idles better" and the like.  Confirmation bias is strong and hard to overcome.  Put the thing on a dyno and get some DA corrected numbers for both fuels and see what you get.

DesertDragon, I'm intrigued, but not surprised.  About 1/3 gal difference in how you fill the tank would result in those numbers.  Are you still running premium?  I'm curious how it averages out over time. Two data points is a little low.


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Offline hppants

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Re: Placebo or Real? 87 or 92 octane
« Reply #15 on: August 27, 2017, 09:26:27 AM »
it's undebatable because science (specifically physics and thermodynamics) don't lie.  And science doesn't care how it makes anyone feel.

If we can all agree that all other things being equal (for the sake of this discussion), the only way for a given engine to make more power is make either burn more fuel or make it burn the same fuel more efficiently.  That is it - plain and simple.

Hopefully we can all agree that just changing the grade of fuel doesn't cause the NH engine to burn MORE fuel, although it might be interesting to learn if the specific gravity of premium fuel is different than regular fuel, and if so, with CV carbs, it MIGHT make a minute difference in the amount of fuel it burns.  Might be more, might be less.  Regardless, the difference would likely be immeasurable.

Now - if we are discussing using premium fuel for the purpose of making more power (and we are), then the only choice we have is to attempt to burn the same amount of fuel more efficiently.  Using science as a basis for our reasoning, since the rate of burn for premium fuel is slower, there are ONLY two possible ways to achieve our goal.  First, we can compress our fuel mixture tighter, making it a more potent "bomb" for the explosion, which in turn will push the top of the piston down harder and thereby make more power.  Notice I use the term "bomb", which is accurate.  The "fire" doesn't make the power, it's the shock wave produced by the mixture of gases.  Regardless, to do this, we have to increase the compression ratio of the combustion chamber.  And we are obviously not doing that by simply switching grades at the pump.

Secondly, we can change our ignition profile to allow the new fuel to burn more evenly.  We will advance the timing to allow the spark to start earlier, and the duration of the burn will be greater and stronger, and thereby produce a better bomb.  But again, we are not doing this by simply switching which pump we put in our tank.

So, using premium fuel as the ONLY variable to make more power is mule fritters, period.

Switching to the second concern - using premium fuel to get better fuel mileage.  Once again, better fuel mileage would mean that the motor is running more efficiently.  For an equal volume of fuel and air mixture placed in the combustion chamber each cycle, somehow a higher octane fuel would burn it more efficiently.  This is not possible solely from the increased octane rating.

Finally, considering the third concern - using premium fuel makes the motor run better, and again, using science as a basis for the discussion, THIS one has the most credibility.  But not from the increased octane.  It would be from the additives, namely any detergents, cleaning agents, and more specifically, any de-carbonizing agents that the premium fuel has v/s the regular fuel.  Using the fuel to remove these deposits, especially around the ring grooves, the piston grooves, the valve seats, valve stems, and the tops of the pistons - this could make the combustion chamber and the exhaust profile more efficient than it was before, and thereby might make the motor run a bit better.  These additives may also do a little bit of a cleaning through the carb jets, passages, etc.

But those kind of changes would not be realized after burning one tank of fuel.  And they probably wouldn't be realized anywhere near the numbers indicated above.  This part is subjective, though.  We don't know what the additives are.

And certainly, proving it empirically would be nearly impossible.  Proving (or disproving) a power increase would be simple - use a dyno or even a day at the drag strip (although less accurate than the dyno) should settle that one easily.  But running a test over a long enough period to cancel out even the most extraneous factors in order to prove (or disprove) fuel efficiency - IMO, that one is nearly impossible.

I'm not trying to piss anyone off.  If burning more expensive gas makes you feel better, than it's a small price to pay (until the motor carbons up).  But don't make assumptions for matters of science with a feeling.  There's plenty of snake oil out there without fanning the flames (pun intended).

Cheers!



(Important disclaimer) - in making this comparison, I am only considering the change in octane rating, which is really the only thing I know.

Offline DesertDragon

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Re: Placebo or Real? 87 or 92 octane
« Reply #16 on: August 27, 2017, 09:36:47 AM »
Okay...
Confirmation bias - When you "hope for and/or expect" a different result... Very familiar with the concept.

I did not expect a different result and conducted the experiment fully "expecting" that there would be no difference at all.
You guys may not "buy" subjective assessments, but again I wasn't hoping for better performance, I just noticed it.

Particularly when around 8 grand going towards redline, the bike would stumble a bit, has been doing it for years and ceased doing it on super. 
Same run, same bike, same rider... only difference being fuel... 
I'm not sure that qualifies as subjective.   
Surprise maybe, but subjective?

As far as warm up, I've been living with the bike for 11 years now, and I noticed a significant difference in time required on choke (~ 50%)
That is not subjective, it is a measurable quantity - time. 

While there could be a difference in tank fill, it has never affected my results before. 
I calculate MPG on every tank, and fill it at the same station, to the same level. 
For the local travel that I do, it's within 1 mpg variance, which is why I decided to do the experiment in the first place.

I never said that the difference in octane made the difference in mileage and performance, and I still would not say that - Other posters did.
Gasoline is an incredibly complex chemical formulation, and there are different additive packages by grade.
Apparently my bike *really* likes Mobil Premium...  How many folks out there can get 50 miles per gallon on a CB 750 ?
Probably not many - But again, I never stated that "you" would see a difference - I just reported that I did.

I'm not sure, but doubt that there would be a difference measurable in horsepower on a dyno.
There are many aspects of engine performance beyond the power produced, especially if some factor in the fuel is improving mileage..
Same power using less fuel does not mean that the engine produces more power at a given rpm, just that it is more efficient...
One thing I did NOT notice, was any difference is horsepower - just the improved mileage, less warm up and lack of stumble close to redline.

Mr F makes a great point that I agree with - the more data points the better.
Unfortunately, I can only do "the experiment" when I'm traveling the same route, or a whole host of other sources of variation can creep in, so it will be a couple of weeks before I can do that again, but I'll post those when I can, accurately, and without "confirmation bias".

That's the best I can do, since I don't have a dyno available; I think the logistics of evacuating one fuel before using another is more trouble than I plan on giving myself; and I doubt there would be any measurable difference anyway.

Whew...


Keep the Rubber on the Bottom!

DD

Offline DesertDragon

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Re: Placebo or Real? 87 or 92 octane
« Reply #17 on: August 27, 2017, 09:56:55 AM »
Pants Man -
Saw your post after mine, but it looks like I proactively addressed them.
As a former Six Sigma Master Black Belt, I take data seriously and I know about variation in process and measurement.
Never said octane made the difference.
Never said it produced more power, I don't think it does.
You are hung up on octane, I'm not.
You are quoting and attempting to establish theory - I'm not - Just reporting observations.
But I can say this - There were multiple positive results that were not subjective, and measurable.
Because you can't explain them, doesn't mean I was hallucinating.
Like Yogi Bearra said, "In Theory, Theory and Practice are the same... In Practice, they ain't"
 haphap
Keep the Rubber on the Bottom!

DD

Offline DesertDragon

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Re: Placebo or Real? 87 or 92 octane
« Reply #18 on: August 27, 2017, 11:58:18 AM »
Hi guys
Lately I switched to 92 octane and my bikes 91NH runs smoother faster and seems to have more power.Noticed idle increased significantly and I adjusted back down but was puzzled why switching the octane increased the idle speed.
Anyway am I experiencing placebo effect or actually my bike runs better.I know it does but need your guys opinions
Suddenly it all makes sense...
It may not be the octane, but other formulation factors that seem to agree with your (and my) bike.
I noticed an unexpected mpg bump (which I will be reconfirming) and in your case, if the same metered fuel results in increased rpm (your idle), it is using less fuel for the same output, which would seem to provide some collaboration for my controlled experiment resulting in improved mpg...

I didn't really notice a change in power output, but one of the most dramatic changes I noticed was that the bike became considerably less "cold blooded"..  My time required on choke was reduced ~ 50%..  Did you notice a similar effect?
Keep the Rubber on the Bottom!

DD

Offline hppants

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Re: Placebo or Real? 87 or 92 octane
« Reply #19 on: August 27, 2017, 02:38:40 PM »
I think we are getting closer to common ground.  Additives could do something, but since I don't know what they are, or what they do, it would be impossible to refute it.

As for the "50% less choke", compared to .... what?  What was the temperature both day?  Barometric pressure?  How long had it been since the bike was run for both instances?  If you are comparing how the throttle performs when the bike is fully warmed, did you somehow apply EXACTLY the same throttle on the same road for exactly the same comparison?

it's an air cooled motor with a manual choke.  At least my bike uses a CPU that is sensing the MAF, O2, coolant temp, and other parameters before deciding that the bike is "warmed up" and therefore, requires no "choke" (which is really an enrichment of the injectors).

I'm sure you weren't hallucinating.  But that doesn't mean that the feelings you got were attributed to the premium fuel.

If we could agree that you simply cannot duplicate two tanks of gas the exact same way under the exact same conditions to make a true comparison, and I'm not sure we can agree at this point, then perhaps a "blind test" might be a good idea.  Get a buddy to help you - go through 10 tanks of fuel (burn at least 90% of the tank) and ask your buddy to fill up the bike when you are not looking.  5 tanks of regular, 5 tanks of premium.  Take notes and declare to your buddy which you think is which.

If you get 7 out of 10 right, then I'll eat crow.  It won't change the science, but at least it will lend credence to your feelings.

I guess by now you have realized that this kind of hits a nerve with me.  For decades, I have felt like oil companies have been misleading the public with their "buy my premium snake oil for 25% more and your engine will run better, get better fuel mileage, etc" baloney (IMO).  There's a Racetrac (independent) fuel station near my house.  It's directly next to a Texaco and a Shell.  On many occasions, I've seen the SAME tanker truck fill up the underground tanks at all 3 locations.  Same exact fuel.  $0.20 difference in price.  Pisses me off....

Offline DesertDragon

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Re: Placebo or Real? 87 or 92 octane
« Reply #20 on: August 27, 2017, 05:25:00 PM »
Pants - I think you're the one grinding the wrong ax here..
YOU seem to be the one with a vested interest in an outcome - Not me.
It apparently offends your sensibilities that you might have been wrong all along...
Sorry you were attacked by that gas station attendant who tried to get you hooked on super.
 
I would like you to explain in your extreme wisdom, how the fuel change described by the post originator resulted in an increase in RPM's enough that he needed to adjust his idle speed. 
Was his intense love of super causing the bike to rev up?

As for the choke, my bike has always been cold blooded..
It's air cooled, so not a major surprise.   
I have always needed to let it run with the choke on for 3 or 4 minutes, and with a small amount of choke when first underway or the engine will bog out. 
It has acted the same way for YEARS and not significantly different regardless of weather, but then I drive when the weather is "nice".

For the week of regular vs super choke comparison, the weather was the same all week and I left at about the same time.
With super, I get no stumble, and I need no choke by the time I'm at the end of my driveway.  This has been consistent.
While it was a freekin' obvious difference to me, I did not expect it, and it was NOT MY FEELINGS attributed to premium fuel.

As far as the mpg test, I drove the same route at the same speed with the same stops and compared mpg results, and they were statistically different.
I did not expect a different result, and I didn't change what I did to bias the test.
The next time I've got a set of local only days I plan on doing it again, as while I always calculate my mpg, I don't have a baseline for the interstate, nor can I create one, because there are too many other variables.

I got into this as an experiment, with absolutely NO predisposition that a fuel change would make any difference... But it did.
I find your contention of bias personally offensive and completely unfounded.

I'm not trying to change your mind - I really don't care what your opinion is.
As far as anything beyond monitoring my mpgs, I am not inclined to go through extreme measures so your panties are no longer in a bunch.

For anyone else out there, give it a try. 
See if it makes a difference. 
Maybe it will, for worse or better..
Maybe you won't notice a thing... but..
Either way you could contribute your OBSERVATIONS rather than blathering your Theory.


Keep the Rubber on the Bottom!

DD

Offline hppants

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Re: Placebo or Real? 87 or 92 octane
« Reply #21 on: August 27, 2017, 06:04:08 PM »
 Fair enough. Agree to disagree. Thanks for reading my post.

Offline Captainkirk

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Re: Placebo or Real? 87 or 92 octane
« Reply #22 on: August 27, 2017, 09:48:53 PM »
Since you guys put it that way... og2
I am fully inclined to agree that it could be the additives making the difference. We all know octane rating is adding additives to increase the anti-knock rating; that's the only reason they used to add tetraethyl lead, and nowadays who knows what to raise that rating? My personal experiences revolved around having a source of 100 octane avgas (which contains 4X the TEL of leaded premium mogas) and the difference in warm up, idle speed when warmed up, and felt perception of acceleration were quite noticeable and apparent, especially when on a long ride where I had to tank up mid-ride with 87 unleaded. I realize this is a moot point because most of you (and now myself) no longer have that access to avgas, but I am simply making the comparison between two halves of the same ride, and they WERE different...to the point where I had to keep revving at stop lights to keep it from stumbling.
Since switching back to 87, I've had to adjust the idle speed up, and it bogs the first mile or so running through the gears until temps start to come up.
So, I'm not questioning the science, but rather, stating there is more to the issue than meets the eye. Could it be ethanol or additives? Quite possibly. But there is a difference.
Measure twice, cut once

Offline sgarnett

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Re: Placebo or Real? 87 or 92 octane
« Reply #23 on: August 28, 2017, 06:36:00 AM »
The slower burn rate of high octane seems to be dismissed as benign or even undesirable. I would expect that to be RPM-dependent. At lower RPM, slower burn could be an advantage.

Offline DesertDragon

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Re: Placebo or Real? 87 or 92 octane
« Reply #24 on: August 28, 2017, 08:34:03 AM »
Since you guys put it that way... og2
Since switching back to 87, I've had to adjust the idle speed up, and it bogs the first mile or so running through the gears until temps start to come up.
So, I'm not questioning the science, but rather, stating there is more to the issue than meets the eye. Could it be ethanol or additives? Quite possibly. But there is a difference.
Aye Captain !
Your experience and mine are the same regarding warm up, which prompted my mention of a very noticeable change.
My idle on super is also a bit (~150) higher, but I like it that way.   
The increase in idle speed  seems to be a consistent observation, as also mentioned by the original poster.

From what I recall, science "IS QUESTIONING".. why something is, a theory as to causation, and experiment / observation for confirmation.
In this case the "science" would be an observed change (in fuel) a theory as to causation (additives?) and an experiment to confirm it.

What science isn't, is the dismissal of observation that does not fit a desired theory, but sadly, scientists are some of the worst offenders in this regard.

For myself, the bike's change in behavior is worth 20 cents a gallon on a vehicle getting 50 mpg...
I'm happy with a change that lets my bike run leaner sooner (less time on choke) and 10% mpg improvement.

I will continue to monitor mpg performance (it's always a good idea - a change for the worse is a great head's up) and post my ongoing results, but I think a new thread would be a better place.  With enough contributors, it might be possible to discover what formulations and their additives seem to be making the difference... Maybe not, but at least it might provide an interesting discussion topic and give people a reason to ... ride...
 ridn2

Back to the original point of this post... trying to make the case that using super results solely in a placebo effect on the rider is ridiculous, IMHO.
 
Keep the Rubber on the Bottom!

DD

 

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