Fuel Grade (regular, mid-range or premium)

[outasight20]

I filled my first tank of premium ever a few weeks ago. Noticed no difference in performance, smoothness, or MPG's. I totally forgot that I had premium in the tank after the initial excitement that maybe there would be a change wore off.

 

[rider1a]

dont' wait your money on anything but a regular. But from what I've heard, avoid the ethanol BS as it reduces your mpg. Hard to avoid it though, it's EVERYWHERE!

Not everywhere:

Ethanol-free gas stations in the U.S. and Canada

 

[VEGASRIDER]

As I creep closer to 100,000 miles, just think how much money I have saved by not spending the extra money on premium. Yeah, it only amounts to less than a dollar in most cases per fillup, but it adds up.

 

[trepetti]

I use regular with nothing bad to report. But I have dirty fingernails since my teens, starting with my 74 Camaro (which I bought new). I believe in 'never create a theory that contradicts observation', but I am stumped. How are we running a 12:1 compression ratio on unleaded regular and not hole-ing pistons? Do the laws of physics cease to exist in our cylinders?

 

[n0other]

Owner's manual has this

"Your Yamaha engine has been designed to use regular unleaded gasoline with a research octane number of 91 or higher."

It's actually hard to get anything lower than 95 where I live so I use that (as most of other people for anything petrol based). There's 98 octane as well, but I don't use that.

 

[Motogiro]

I use regular with nothing bad to report. But I have dirty fingernails since my teens, starting with my 74 Camaro (which I bought new). I believe in 'never create a theory that contradicts observation', but I am stumped. How are we running a 12:1 compression ratio on unleaded regular and not hole-ing pistons? Do the laws of physics cease to exist in our cylinders?

Fuel injection, and timing controlled by an ECU? I remember older cars and the much higher failure rates of motors. I would attribute that higher failure rate to a less efficient fuel and ignition system. I remember thinking when they first started reducing compression ratios and adding cheaper unleaded fuels with emission control systems on cars that high performance was a thing of the past but it turned out to be good. FI became more refined and it seemed engines lasted 100,000 plus miles instead of failing at 40 or 50 k

 

[FIZZER6]

I'm going to switch back to 87 this season. Premium fuel is now as much as $.50/gal higher priced than regular! That's $2 more per tank for a debatable benefit.

 

[Water Bear]

It's probably true that a lot of people buy premium for non technical reasons.

My understanding of the difference is that higher octane rating = higher knock resistance. I hear that on most all modern vehicles, built in anti-knock measures make this more or less a non-issue.

I used premium based on the assumption that my sporty engine would run hot, and that might increase the probability of detonation (knocking). I just assumed the bike probably took higher octane fuel. Knowing now that the MOM says it's not an issue, there is really no reason to use high octane fuel anymore.

Edit: Seeing that there's some discussion on this already, part of the reason modern engines are knock resistant is that they have ECUs. When the ECU sense knock conditions, it can do things like retard ignition to reduce the temperature in the engine.

 

[FinalImpact]

^^ but our engine does not have a knock sensor! Thus as the temps and loads increase, destructive knocking/pre-ignition/detonation can damage this engine. For those of you who tour in hot weather, added bags, added a passenger, AND added that 17th front sprocket, you are playing with fire running low octane fuel! Lower octane fuels "** CAN **" lead to destructive detonation when the circumstances stack up. Added carbon deposits from never revving the engine likely increase this tendency by another factor of 10!!!

My personal experience is this: I can hear mine knock on take off when temps are in the 85F and the engine temp is >195F. Granted that is rare but now add in this; When I take off going up hill its likely to detonate on 87 octane fuel. As someone mention, Running at sea level also increases the odds as do Dryer Climates. The air is less dense and offers less cooling in terms of cylinder filling. A cooler, denser air charge is less likely to cause detonation than hot air on a dry day. From this, I run Plus rated fuel 80% of the time. Any dry hot day I plan a ride, it gets Plus!
My bike has TB exhaust and stock gearing. I can't imagine I am the only one who has this happen and suspect many do not hear it happen! If its happening above 3.5K I doubt I could hear from all the F'ng noise the damn engine makes anyway as it has no noise damping properties. Its a race engine strapped between your legs!

FWIW: the ignition advance curve on the FZ is a fixed rate based upon RPM so it holds a linear vector increasing with RPM. It DOES NOT take into account engine load, gas quality, pinging, detonation, throttle position, gear selection, or anything tangible like a modern car does to asses calculated load imposed on the engine.

The fact that ignition timing control is fixed by RPM is a key ingredient limiting the FZ's hp output to 90+. At 14,000 RPM the resonant frequencies in the block would drive a conventional Pizzo electric knock sensor crazy as it would require very selective "electronic filter" to distinguish between knock of fuel detonation and reciprocating parts moving at crazy high velocities. Its likely why it doesn't have it as its a less expensive bike.

FWIW: I am attempting to procure knock sensor capable of ignoring the thrashing and listening for "detonation" so I can advance the timing and make more power. It must be! Also; our air box sucks as it takes the engines heat and traps it inside increasing the odds of detonation.

JJD952!

 

[iviyth0s]

Regular here (87 Oct. US Blend).

I'll have to try premium for two tanks after two tanks of Regular and then based on MPG results, I will pick the victor (also taking into account, the cost differences). So far I haven't noticed anything wrong with Regular, but this is my first tank of it since I bought the bike so for all I know he could have used premium all the time and I have a mixture of both sloshing around in there.

 

[Helvete]

95 is the minimum I've seen in the UK in years, I use that, I don't bother with the 98, it's too expensive here anyway.

 

[ctbandit]

Holy **** I can't believe how many people are wasting their money on premium..

 

[ezburgess]

wasting money? its like 50 cents more per fill up. I'm poor and even i can afford that. i feel like the bike has a lot of compression, so i use premium just in case. i just snapped a timing chain in my car because it was knocking so hard.

 

[iviyth0s]

wasting money? its like 50 cents more per fill up. I'm poor and even i can afford that. i feel like the bike has a lot of compression, so i use premium just in case. i just snapped a timing chain in my car because it was knocking so hard.

I just want to see documented evidence of the benefits before I'm on board.

In my case, I'm not going to have access to a dyno to assess the power improvement/detraction that the different fuel grades may or may not cause. I will however be able to record and compare the possible fuel economy change.

It may just be $0.50 or a dollar more a fill up but that's still a large sum of money that those rich bastard oil companies do NOT need. (thinking about all the members on here alone, many of which are running premium and may not have to. Not to mention many others in cars/trucks that will matter more)

 

[FinalImpact]

In my case, I'm not going to have access to a dyno to assess the power improvement/detraction that the different fuel grades may or may not cause. I will however be able to record and compare the possible fuel economy change.

You're NOT going to see any power improvements or MPG increase. The only case where the fuel would get you more power/down the road further is if the Ignition Timing could advanced more than it does from stock.

Best case is if you break all the boundaries I listed above/below, your engine doesn't destroy itself on higher octane fuel!

For those of you who tour in hot weather, added bags, added a passenger, AND added that 17th front sprocket, you are playing with fire running low octane fuel! Lower octane fuels "** CAN **" lead to destructive detonation when the circumstances stack up. Added carbon deposits from never revving the engine likely increase this tendency by another factor of 10!!!

JJD952!

For those who load it up Good and Heavy, Listen to your engine when you take off. Does it make knocking sounds?

 

[iviyth0s]

You're NOT going to see any power improvements or MPG increase. The only case where the fuel would get you more power/down the road further is if the Ignition Timing could advanced more than it does from stock.

Best case is if you break all the boundaries I listed above/below, your engine doesn't destroy itself on higher octane fuel!



For those who load it up Good and Heavy, Listen to your engine when you take off. Does it make knocking sounds?

I'd say a power/MPG change is possible if the higher grades of fuel have less ethanol in it and more pure gasoline, because then it'd be more energy dense. But I think NJ puts that corn garbage in all the grades evenly....though we shall find out!! (otherwise, yeah...there's no way there'd be a noticeable difference

 

[regder]

For those who load it up Good and Heavy, Listen to your engine when you take off. Does it make knocking sounds?

I've ridden at times two up (~300lbs) plus about 60-70lbs of luggage and haven't had any issues. Presently above 110k km (~69k miles), running it's whole life on 87octane. Valves looked pretty clean when I checked them at ~84k km too

 

[FinalImpact]

I've ridden at times two up (~300lbs) plus about 60-70lbs of luggage and haven't had any issues. Presently above 110k km (~69k miles), running it's whole life on 87octane. Valves looked pretty clean when I checked them at ~84k km too

.. .. ..

My personal experience is this: I can hear mine knock on take off when temps are in the 85F and the engine temp is >195F. Granted that is rare but now add in this; When I take off going up hill its likely to detonate on 87 octane fuel.

I don't doubt all is well for you and others. I'm just saying when enough things stack up, some can damage their engine. I've heard it on take off but at no other times and as said, its so noisy it'd be hard to tell at 9000 RPM so who would be the wiser???

Just trying to dispel some of the myths. i.e. why some "may need it" and how its NOT going to help increase MPG's without the addition of a timing advance module.

 

[Ohendo]

Running at sea level also increases the odds as do Dryer Climates. The air is less dense ....

I agree with most of your post, but the above portion is inaccurate. Air density decreases with increasing altitude. At sea level it is greater than at elevation.

 

[mave2911]

BUT - colder air is more dense than hotter air.

The decrease in air density from elevation is more than offset by the increase of air density due to a drop in temperature - up to a certain point.

Cheers,
Rick