Fuel Grade???

[Centerline]

BTW, FWIIW, 87 or 89 octane for my FJR. It does knock very lightly with 87 at low RPM initial acceleration. Knocks very light for about 1/2 second.

 

[Fallen Jim Rides again]

Research is almost complete. I have a question though. Does the FJR have a knock or ping sensor?

 

[SkooterG]

Research is almost complete. I have a question though. Does the FJR have a knock or ping sensor?

Nope.

Iffin it a did, you would never hear a knock or ping. The computer would compensate for any knock or ping condition eliminating it, to the detriment of power. (Simple answer)

 

[Fallen Jim Rides again]

That is what I thought, but wanted to be sure. That being the case, higher octane MIGHT, under some conditions, result in slightly more hp. Compression isn't the only factor in ping, just the primary. As I pointed out before, spark timing also has an effect. A higher octane rating (which BTW, isn't exactly the same as gasoline of that exact octane formulation but will do for most purposes) will allow for not only higher compression, but will also permit the timing to be advanced slightly both in terms of total advance and in terms of how early in the rpm band that total advance can be achieved.

If Yamaha had included a ping sensor, we could probably get even better performance due to the computer being able to advance the timing right up to the limit of ping inducement, along with the other engine management.

But ya know what. While I suppose there is never actually enough power for most of us the truth is this motor will shred the back tire in very short order and roll on is so good that I often twist it up just for the hell of it.

Now I know way too much about gasoline to boot.

Thanks Skoot.

 

[Ignacio]

Now I know way too much about gasoline to boot.

You think you can shred your back tire? Try this Gasoline FAQon for size.

 

[Fallen Jim Rides again]

Now I know way too much about gasoline to boot.

You think you can shred your back tire? Try this Gasoline FAQon for size.

Oh, sure more information. And worse still, information that contradictes earlier statements.

All pretty much the same huh?

There seems to be a perception that all gasolines of one octane grade arechemically similar, and thus general rules can be promulgated about "energy

content ", "flame speed", "combustion temperature" etc. etc.. Nothing is

further from the truth. The behaviour of manufactured gasolines in octane

rating engines can be predicted, using previous octane ratings of special

blends intended to determine how a particular refinery stream responds to

an octane-enhancing additive. Refiners can design and reconfigure refineries

to efficiently produce a wide range of gasolines feedstocks, depending on

market and regulatory requirements. There is a worldwide trend to move to

unleaded gasolines, followed by the introduction of exhaust catalysts and

sophisticated engine management systems.

* Bold is mine

This also supports my earlier suspicion that gasoline can be manufactured to various results. Also this document suggests trying various different brands in your vehicle due to wide variances in performance. Hmmm.

too many variables.

OTOH, there are many of us here, who live in various parts of the country/world. Maybe there is a best gas for the FJR, at least regionally. Perhaps a new never ending thread of comments on what is the best brand for my/your/our type of riding? I think I will get the higher octane when I ride with my HD friends so that the engine doesn't clatter when I inevidably lug it down trying not to run over someone.

Or not.

As for tire shredding, I will be replacing the Z4s in a couple of weeks so hopefully I will get a couple of pics of their final moments of glory and post here. How much smoke do ya think is left in 'em?

Hey, Skoot, can ya hold this shovel for me for a little bit?

I think this hole is deep enough.

 

[redtail]

So, my Mechanic was right! Cheap gas is cheap gas!

 

[04FJR4ME]

Iffin it a did, you would never hear a knock or ping. The computer would compensate for any knock or ping condition eliminating it, to the detriment of power. (Simple answer)

Greg, not really true, a knock sensor retards timing when it hears a knock in the engine, so you will hear it knock before the computer retards the timing!

Remember the days of 102 octane chevron white gas used in 11 to 1 compression engines in the lates 60's and early 70's, and the cheap stuff was 93 octane. now premium is only 91 octane or less and we call it premium with much of additives that dilute the gas to clean the injectors. burn what ever floats your boat and you can afford, I see the only difference is that now we use fuel injection which atomizes the fuel better then carbureted engine and can use the fuel more efficiently.

Oh, the only winners are the oil company that is selling everyone regular at a premium price! :lol:

 

[Fallen Jim Rides again]

. . . . . .
Oh, the only winners are the oil company that is selling everyone regular at a premium price! :lol:

Hey, at least they aren't charging us the price of fancy bottled water.

 

[SkooterG]

Hey, Skoot, can ya hold this shovel for me for a little bit?  I think this hole is deep enough.

Don't want no stinkin shovel! Actually, to add a little fuel to the fire , here is a link to another fuel article. Long and sometimes technical, but with lots of good information.

Chevron Fuel Efficiency article

Greg, not really true, a knock sensor retards timing when it hears a knock in the engine, so you will hear it knock before the computer retards the timing!

Hey James, according to the above article, knock sensors and the computers retard the timing before the operator ever hears the knock. That's what I thought, but who knows?

And for crying out loud Ignacio, its taking me forever to get through your little gasoline article, though I must admit, I am learning a few things.

 

[Ignacio]

And for crying out loud Ignacio, its taking me forever to get through your little gasoline article, though I must admit, I am learning a few things.

At the next rally we're at....maybe as a bonus they'll set a challenge to distill our own gallon of 99% heptane with a Leatherman, Big Gulp cup, straw, and road flare. Point value: 1,000,000 points.

 

[04FJR4ME]

Hey James, according to the above article, knock sensors and the computers retard the timing before the operator ever hears the knock. That's what I thought, but who knows?

I am not sure what they are doing for engine knock these days, been out of the automotive field for some time now.

But I do know that we use to test the knock sensor by simplying tapping the engine and we can see the timing retard itself, it is just what it's name, it is a knock sensor and I am not sure how it can predict the engine will ping prior except if it also monitors the engine load and knows when it should ping, then if that's the case, why would it need the sensor?

No big deal, just wondering if anyone can shine some light on this subject?

Here is a link to knock sensor basics 101

https://www.autoshop101.com/forms/h38.pdf

Not sure what Chevron is talking about, I can't even find the part that it talks about the knock sensor?

 

[weekend rider]

Wow ,a lot of good information on fuel.

After reading all of this information, I think I got gas :haha:

 

[jestal]

Not all knock sensors and knock control systems are the same and they are not created equal. Some work better than others. Some engines will have a knock control system that will often allow audible knock before its takes preventative action...i.e..you will hear knock despite the knock control system. Other sytsems will control to such a low level of knock that it is not even discernable by a knowlegable observer. So....you cannot make a blanket statement about whether one would hear knock or not with a knock control system.

Other things to keep in mind about knock systems is the different engine architectures that the systems are on. A V8 engine with a single knock sensor can be a challenge to make the knock sensor "hear" each of the 8 cylinders knock. Often the sensor will be deaf to one or more of the cylinders so if that cylinder knocks first then you might hear it before the other cylinders start to knock and the system reacts. Most modern systems use multiple knock sensors to avoid the "deafness" problem and look at instantaneous crank position to determine which exact cylinder is knocking so that individual cylinder knock control can be accomplished.

One could write an entire book just on knock sensors and knock control theory. Needless to say that it is impossible to cover all aspects of it here. Also, realize that the knock control system logic has matured over the years so the performance of a knock control system on a 10 or 15 year old car is hardly representative of how all knock control systems work or what the capability of a knock control system is.

Not to defend Harleys....but.....the reason they need high octane fuel is not because of antiquated combustion chambers but because they have large displacement cylinders which necessitate large combustion chambers. The larger the chamber the longer the charge takes to burn and the longer the end gas is exposed to heat and pressure and thus the more likely it is to detonate causing spark knock. Simple geometry. The same exact chamber shape and design is going to be FAR more knock tolerant if it is small and tiny on a small bore (like on a 4 cylinder 600 ccsport bike) compared to a large displacment cylinder with a larger bore. Bore size is a very important aspect of spark knock sensitivity all other things being equal.

I won't argue with the theory that elements of higher octane fuel might have slightly lower heat energy but the practical fact is that there is little to no difference between the powe producing capability of regular and premium fuel. The only difference is the resistence of the premium fuel to spark knock. If the engine needs premium due to chamber design, chamber size, state of tune, compression ratio, etc....then premium will allow operation at the rated power level with no spark knock.

 

[zzkenoman]

+1 for 87

 

[odot]

I'd add another link here but this thread is all linked out.

 

[raclow]

And I got in trouble for asking an oil question :erm:

+1 for 87. Manufacturer suggests this:

Pump Octane Number [(R+M)/2] of 86 or higher, or a research octane number of 91 or higher. If knocking (or pinging) occurs, use a gasoline of a different brand or premium unleaded fuel. Or use Gasahol, with the ethanol not to exceed 10%. Yamaha doesn't want you to use Methanol. Page 3-10 in Owners Manual

Personally, I'm trying to cut back on the Meth myself

As long as you have fuel, the bike is moving, the engine is running, and you aren't walking, what is the problem? :blink: