Pre-detonation?

Post by **Indawoods** » 12:14 pm Oct 01 2006

Is anyone having an issue with pre-detonation?

I have found that I can run lower octane gas without pinging with my RB modded head just by running the AMSOIL Interceptor. I was always affraid to try it but a Amsoil Rep asked me to try it... and sure enough! I now run 89-90 octaine gas and no pinging. This stuff is amazing!

bradf · Post by **bradf** » 07:14 pm Oct 01 2006

I have never tried anything less than 93.

cmot · Post by **cmot** » 07:23 pm Oct 01 2006

What is Amsoil intercepter? I use premium with a octane booster, pinging has never been a problem though.

Post by **Indawoods** » 07:26 pm Oct 01 2006

Think about why you run high octane gas. Habit? Think it makes your bike run better? Why?

The major reason folks run high octane gas is for pinging issues which is pre-detonation. This is because lower octane gas is more volatile than premium fuel and tends to ignite under compression. In my mind, this means that the low octane stuff packs more energy than premium. Why not harness this energy with a pre-mix that stabilizes the fuel so that it is as stable as premium?
It is a money saver...

Post by **Indawoods** » 07:28 pm Oct 01 2006

cmot wrote:What is Amsoil intercepter? I use premium with a octane booster, pinging has never been a problem though.

Look up at the top left of the page... click the link, go to Two-Stroke Oil on the left and select Interceptor on the drop down list. There you can read all about it!

AZRickD · Post by **AZRickD** » 10:14 pm Oct 01 2006

The octane rating is a measure of how fast the flame propagates compared to straight Octane fuel vs Heptane.

91 octane fuel (which is the common "premium" here in Phoenix) burns at a rate 91% of the way up to octane.

How much energy it has is another matter.

Now, when it's 115F in Phoenix, I'll stick with 91 octane, but in the winter, when I'll likely be riding in 40F to 60F, I'll give 87 octane it a try and report back.

Fredette can fix my pitted piston and grenaded head, right?

Rick

Post by **Indawoods** » 10:23 pm Oct 01 2006

Hmmmmm..... It is my understanding the Octane rating is only a measure of how resistant a fuel is to knocking or pre-mature detonation. Everything I have ever read on the matter backs that up.

Oh..and yeah... Jeffy will fix ya right up!

hoodoo · Post by **hoodoo** » 10:24 pm Oct 01 2006

I have run regular gasoline, not premium, all season. Wide open desert riding to tight woods. No problems at all. I do use Amsoil Intercepter.

AZRickD · Post by **AZRickD** » 10:58 pm Oct 01 2006

It is my understanding the Octane rating is only a measure of how resistant a fuel is to knocking or pre-mature detonation.

Yes, but that's a function of whether it is more like heptane or octane in the speed in which it propagates the flame front. Kind of like the difference in black powder and smokeless powder for you gunnie-types out there. Or burn rates of smokeless pistol powder (fast) vs rifle powder (slow).

Rick

canyncarvr · Post by **canyncarvr** » 11:21 am Oct 02 2006

Re: Think about why you run high octane gas. Habit? Think it makes your bike run better? Why?

Habit? No.

Think? No.

1. The people that made the engine specified it. Yeah, and they specify 32:1, too.

2. I know it runs better. Well, I think it does, too, the latter preceeding the former.

More energy in lower octane means more energy? No.

My hand is attached to my arm. It has 'X' amount of available energy. In an uncontrolled movement it has the ability to smash an egg. In a controlled movement, it has the ability to crack an egg and empty it from the shell in a sunny side up fashion in a pan.

I don't know the symptoms of 'pre-detonation'. I know detonation has been referred to as, 'The Silent Killer'. You can't hear it. By the time you do hear the effect of the use of an insufficient fuel, it's too late.

You can run an insufficiently spec'd fuel, have 'no problems at all' and destroy your engine in the process.

You can run an insufficiently spec'd fuel, have 'no problems at all' and another bike just like yours that IS running a sufficient fuel will wax your butt, and I'm not talking about bikini lines, either.

There should be no reason to explain the process. It is apparent that the fuel charge exploding before TDC isn't going to work as well as a fuel charge that is still BURNING AFTER TDC. The object, indeed, is to push the piston DOWN, not smack it on its head on the way UP.

Post by **Indawoods** » 11:46 am Oct 02 2006

Agreed.

I looked all through the manual and there is no mention of required Octane specified.

The only way to tell what is going on inside there is to be in there when it happens. And even then it would happen so fast that I doubt if you could tell what gas is working correctly and what isn't.

Way too many variables to take into consideration. But it stands to reason that a mild KDX is not going to require a high octane fuel.

canyncarvr · Post by **canyncarvr** » 02:49 pm Oct 02 2006

This subject and subjects of its type can be argued, discussed and cussed over for a tad just short of foever.

It does indeed 'stand to reason' that a KDX would not require a high octane fuel.

It stands as well to reason that most KDX riders will notice the difference between 87 and 92 octane fuel regardless what that difference actually is.

I think my bike runs (and ran before higher static compression) better with 92 than 87. It sure runs better on toluene..and at about $48 a gallon that difference is good enough that I pay for it.

**edit**
I buy it by the gallon, NOT the quart. It's about $12 a gallon, not $48. Mine comes from a paint store.**edit**

If you think your bike runs better (or just as well) on 87 as 92, run what suits you. There are indeed many variables to take into account. My peace of mind from running 92 suits me. I've seen detonation damage in engines.

The last one I saw cost me about $5000.

Considering that premium fuel around her runs $.20 a gallon over regular fuel, that means a good day of riding and using premium fuel will cost me about a dollar more than if I used regular. Further consideration of what it costs to GET me 'there' (wherever there is), what I spend for bike maintenance, lunch, and gear, a dollar diminishes to a diminution.

Post by **Indawoods** » 08:33 pm Oct 02 2006

Toluene is an aromatic additive which is a good thing and it does make the bike run real well and I do use it.

This running lower octane gas with the AMSOIL Interceptor was a test. Believe it or not, the guys at AMSOIL are very passionate about their products and have done extensive testing on their products vs, Mobil and all the other manufacturers. Their goal is a simple one... to be the best. I have had a Rep and a chemist on the line at the same time when I had questions about shearing and thermal breakdown.

The testing they did with the Interceptor and different grades of gasoline was the subject of a paper that is being written... and to me...AMSOIL is right up there with 3M.

There is one simple fact about where we should be going in the future and that is running full synthetic made right here in the USA. We need to get off of this foreign oil kick. The more we use synthetic oils, the faster the prices go down.

cmot · Post by **cmot** » 09:20 pm Oct 02 2006

I'm not completely up to snuff on facts

but I do believe that there is detonation and then there is pinging, detonation is deadly pre ignition hammering of the piston and pinging is exploding late in the cycle causing a noise but not deadly like predetonation. For years in autos pinging problems are solved with higher octane or fuel booster additives. While this will do nothing for a motor that is pre-detonating due to timing or compression issues . On the high octane question. two stoke engines are basicly the same as 20 years ago and we were running a lot higher octane then than now we have just lived with fuel getting lower and lower octanes. I'll stick with what works for me...Thanks...

cmot · Post by **cmot** » 09:38 pm Oct 02 2006

I just read the specs on the Amsoil and it does sound good. Ill add it with what i,m allready doing with premium gas. It's not that expensive to add a little extra protection. I like the detergent action on the kips valves.

AZRickD · Post by **AZRickD** » 09:53 pm Oct 02 2006

I doubt if you could tell what gas is working correctly and what isn't.

A little dyno time will tell the tale.

Rick

Post by **Indawoods** » 09:55 pm Oct 02 2006

Yep.. got one of those!

canyncarvr · Post by **canyncarvr** » 12:29 pm Oct 03 2006

Inda..I'm sure you've said, but what oil/fuel ratio do you use?

Not to get picky, but detonation is defined as:

A condition, in which, after the spark plug fires, some of the unburned air-fuel mixture in the combustion chamber explodes spontaneously, set off only by the heat and pressure of air-fuel mixture that has already been ignited.

(From: http://www.autocenter.com/about/ ..returned by Google from 'define')

Note that detonation does not necessarily have anything to do with pre-ignition. Maybe it happens during 'normal' properly timed and sourced ignition.

Yes, pre-ignition is different. It is ignition of the mix prematurely and not from the primary ignition source, hence the 'pre' part.

Hence why I said I don't know what predetonation is. I've not heard that term..I think it's misspeak in this case. Certainly some situation does exist just prior to detonation, but I don't think it's coined 'predetonation'.

Yes, I understand the following definition of 'pinging' is out there, too:

Knocking (also called pinking or pinging)—technically detonation....

It is my understanding that the two (detonation/pinging) are NOT the same. I don't think every detonation leads to a 'ping' that you can hear..thus the 'silent killer' part.

Detonation can be resolved by increasing octane, but also by redesign of the head to preclude 'pockets' from developing and by intake design that brings about a better 'flush' of spent fuel AND a consistent mix of fresh fuel (like 'turbo swirl' heads. Part of why the term 'port and polish' is so stupid.).

And there's the squish band of two strokes............

It's more complicated than 'It's the octane.'

Like Inda said....many variables.

BTW, I have a dyno, too! I've found it works great particularly when properly prepared prior to riding..lubricated if you will...using Ski's butt crack cream.

Available in the 'Feminine Hygiene' aisle of your local drug store...it's a Monostat product.

(For those in Rio Linda, I'm referring to a 'seat-of-the-pants' tattle. That's my dyno! Ski's cream does work great!!)

Post by **Indawoods** » 01:02 pm Oct 03 2006

In my definition understanding...

Detonation and Ignition means the same thing!

canyncarvr · Post by **canyncarvr** » 01:41 pm Oct 03 2006

With nitro, C5, and trinitrotoluene maybe.

Not in internal combusion engines.

The following are true statements..misunderstood by a lot of folks:

Octane rating is in no way correlated with engine power or efficiency. There is more potential energy in a gallon of diesel fuel than a gallon of gasoline, yet the diesel fuel has a much lower octane value (more on that below).

Interesting reading from:

http://www.prime-mover.org/Engines/GArt ... ctane.html

KDXRIDER.NET

KDXRIDER.NET

Pre-detonation?

Pre-detonation?