[cintidude04]

Runs better because it isn't tuned right.

[Old Skool]

Runs better because it isn't tuned right.

I believe you. I have only had it this season. Before that I rode mostly heavy cruisers so I joined katriders to learn all this cool stuff from you guys. Your knowledge base for these bikes on this forum is awesome and I thank you for the free lessons on here. There is so much to learn on this site but that's a big part of the fun. ride tinker ride, Repeat LOL

Tom

[cintidude04]

If you richen up your af mix a little bit you will be able to run 87 just fine.

[Old Skool]

If you richen up your af mix a little bit you will be able to run 87 just fine.

Perfect thanks for the tip I will give that a go.

Thanks Again

Tom

[Oreos_stang3]

Fun little thread to read. I put 93 in mine. I get my gas from QuikTrip. It is top tier gas so it is damn good gas.

[astevens54]

I just read a great article in Throttle Nation volume 2 Issue 7 about "The Gas Factor" and here's what I get from it. One, if you bike is stock use the recommended octane. The higher the octane rating, the more resistant to detonation it is. For engines with higher compression and turbo's it is normally recommended to use higher octane. Basically, the article goes through pre and post detonation and how it effects the performance of your engine based upon octane. It also stated use non ethanol gas is preferred and that is easier on the fuel pump and seals and that it delivers more energy with the potential for more power. If you can get your hands on this copy and want to know more about gas in your bike, this is the article to read. It cleared up some things and backed what I thought (always been told) about octane. It went on to say if 87 octane is recommended for you bike and it's stock, you're wasting your money on anything higher because it's more resistant to detonate. This in turn can even cost a little horse power. I can try and convert this article to OCR and post it if you all would like?

[numus]

I just read a great article in Throttle Nation volume 2 Issue 7 about "The Gas Factor" and here's what I get from it. One, if you bike is stock use the recommended octane. The higher the octane rating, the more resistant to detonation it is. For engines with higher compression and turbo's it is normally recommended to use higher octane. Basically, the article goes through pre and post detonation and how it effects the performance of your engine based upon octane. It also stated use non ethanol gas is preferred and that is easier on the fuel pump and seals and that it delivers more energy with the potential for more power. If you can get your hands on this copy and want to know more about gas in your bike, this is the article to read. It cleared up some things and backed what I thought (always been told) about octane. It went on to say if 87 octane is recommended for you bike and it's stock, you're wasting your money on anything higher because it's more resistant to detonate. This in turn can even cost a little horse power. I can try and convert this article to OCR and post it if you all would like?

Well I had a long response to this post and somehow it all got lost

Basically the article is flawed... The detonation they are describing is the self detonation of gasoline due to compression, not due to spark. Higher octane allows a higher compression without fear of premature ignition... premature ignition (ignition before desirable compression has occured and before a full cycle on the piston) can cause the audible knocking and pinging.
93 does not contain more ethnaol then 87 cause they are limited to 1-10% by volume. Actually some stations use less (or no) ethanol in their 93 octane gasoline you just have to either ask the person (if they know about it) or look up the state quality ratings on the gasoline (in Florida DACS does all gasoline testing).
Also good to note: In Florida (not sure about other states) but the gas stations only have storage tanks for the lowest and highest octane level gasoline... if the pump has 87, 89 and 93 they only store 87 and 93... It uses a blend door for the 89 and usually they come out more like 90-91...

[astevens54]

Well I had a long response to this post and somehow it all got lost

Basically the article is flawed... The detonation they are describing is the self detonation of gasoline due to compression, not due to spark. Higher octane allows a higher compression without fear of premature ignition... premature ignition (ignition before desirable compression has occured and before a full cycle on the piston) can cause the audible knocking and pinging.
93 does not contain more ethnaol then 87 cause they are limited to 1-10% by volume. Actually some stations use less (or no) ethanol in their 93 octane gasoline you just have to either ask the person (if they know about it) or look up the state quality ratings on the gasoline (in Florida DACS does all gasoline testing).
Also good to note: In Florida (not sure about other states) but the gas stations only have storage tanks for the lowest and highest octane level gasoline... if the pump has 87, 89 and 93 they only store 87 and 93... It uses a blend door for the 89 and usually they come out more like 90-91...

What about the flashpoint being higher for 93?

[numus]

What about the flashpoint being higher for 93?

Spark plugs can hit tens of thousands of Kelvin... Flashpoint is not that big of a factor... All it means is the gas will burn hotter.
The flashpoint being higher is the primary reason of higher octane gasoline tho... That is what causes it to survive higher compression without self-igniting.
You can relate it all back to Pv = nRT (the ideal gas law). Forget about nR cause they are both held constant. as Pressure increases, volume would have to decrease at the same rate to hold T constant. Since pressure is increasing at a higher rate then the volume is decreasing this causes an increase in Temp. The higher flashpoint allows pressure it increase higher without T hitting the flashpoint. Once T hits the flashpoint, it will be hotter due to the higher pressure.


Now.. As the spark plug ignites, it causes a rapid expansion of ionized gas that increases the pressure beyond what the piston was contributing. As long as the gap is the proper distance and the electrode of the spark plug isn't obstructed, it shouldn't matter if it is 87 or 93.. it will ignite the same... When you dont have a proper gap and/or the electrode is obstructed, this is where the possibility of 93 having more unburnt gas then 87 in the exhaust system. But this is when dealing with a huge obstruction or just a bad spark plug... Under normal operating conditions the spark plug (even when hindered) will still greatly exceed what is necessary to burn 93...

[05RedKat600]

You are also forgetting that higher octane fuels actually burn slower than lower octane fuels. The people who run timing advancers on their Kats may actually need to step up to the next octane rating of fuel.

[numus]

You are also forgetting that higher octane fuels actually burn slower than lower octane fuels. The people who run timing advancers on their Kats may actually need to step up to the next octane rating of fuel.

That comes with the increased pressure requirement for ignition... takes a fraction of a second longer to burn because it has to hit a higher pressure... Granted we are talking a fraction of a fraction of a second but it probably is long enough to mess up a timing advancer...

[05RedKat600]

That comes with the increased pressure requirement for ignition... takes a fraction of a second longer to burn because it has to hit a higher pressure... Granted we are talking a fraction of a fraction of a second but it probably is long enough to mess up a timing advancer...

You should run higher octane fuel with a timing advancer. It won't mess the advancer up.

There is no increased pressure requirement. You can run it in any motor. However, it will withstand higher compression, and therefor is ideal to run in high compression motors or motors with advanced timing, due to the slower flame wall in the combustion chamber.

[numus]

You should run higher octane fuel with a timing advancer. It won't mess the advancer up.

There is no increased pressure requirement. You can run it in any motor. However, it will withstand higher compression, and therefor is ideal to run in high compression motors or motors with advanced timing, due to the slower flame wall in the combustion chamber.

Sorry if it was implied that I ment that you have to have a higher pressure requirement. My statement was ment to stand that since there is a higher pressure requirement for ignition, it will cause ingition to occur fractions of seconds later then it would under lower octane gasoline.

[loudnlow7484]

It also stated use non ethanol gas is preferred and that is easier on the fuel pump and seals and that it delivers more energy with the potential for more power.

Not to further f*** with this article, but this is also wrong. Gasoline contains more specific energy than alcohol (either ethanol or methanol), but alcohol has the potential for MUCH MUCH more power than pump gas could ever dream of. This is why a lot of forced-induction cars switch to E85, because they can run boost on E85 that was previously race-gas-only territory. Specific energy only matters if the a/f ratio stays constant, but stoichiometric ratio for gasoline is around 14:1, and for alcohol is around 9:1. That 50% greater volume of fuel puts the specific energy for the air-fuel mixture well above pump gas.

Alcohol is harder on the pump, though (it has to pump 50% more fuel, after all), and on any seals that aren't made of materials appropriate for it.

[05RedKat600]

Sorry if it was implied that I ment that you have to have a higher pressure requirement. My statement was ment to stand that since there is a higher pressure requirement for ignition, it will cause ingition to occur fractions of seconds later then it would under lower octane gasoline.

There is no higher pressure requirement or temperature for ignition though. You have it backwards. It burns slower, therefore you need advanced timing and are allowed to run higher compression to use it fully. It'll work in Kats and other cars, you're just ****ing away money.

Ignition point/temperature is the same for gasoline regardless of octane rating. It is the burn speed and propagation of the flame wall that changes with octane. Hence the need to ignite it sooner than lower octane gasoline. It is also more resistant to detonation than lower octane, thus allowing the use of higher compression. It doesn't require it.

You have the concepts down, but the implementation is slightly incorrect.

In regards to alcohol, that is BS. There is a reason that drag cars burn alcohol and not gasoline. Also, different sources of ethanol contain different amounts of energy. The corn ethanol we use is around 70% the energy of gasoline. The sugar cane ethanol Brazil uses is about 110-115% the energy of gasoline. Loudnlow explained it well also.