i have an 09 SF. I have an AEM EUGO Wideband Air-Fuel Ratio setup on my bike. Everyone has said that the bike runs lean stock. At the moment I have stock jettin stock box, Uni filter, HMF Slip-on.

I have always used "the best" at the pump. At idle the bike tended to "load-up". It would be right around 13.5 then richen att the way to 11.9. I tried to adjust the idle screw but it would just interfere with 1/4 throttle eventually. I even tuned it at the 1/8 throttle 1800 rpm-2k rpm guidline. Still loads up.

At 1/4 throttle we are in use of the needle, its dead on at 13.5-12.9 kinda rich.
WOT, we are at 12.5-11.5. Kinda rich.

My drivability in 6th at 40 mph isnt that great, lack of power. So this week I have eased into 87 octane.

My idle is hanging solid 13.8-14 now where it should be. My mid is a little leaner, where it need to be, solid 13.5-13.7, my WOT is staying 12.5-12.8.

My driveability is better.

Another thing that affirms this idea, is when I had 1k miles on the big i tore it down to do a big bore, I always used premium. There was a TON of carbon on the stock piston, as if the fuel wasnt being burnt off. Im starting to think this may be why the overseas version have a hotter ignition. Most of their fuels are premium.

 

Does Kawi recommend an octane level for our bikes?

 

These bikes aren't as lean stock as most people think they are just strangled with restrictions form the intake and exhaust in stock form. And simple exhaust mods like a slip-on don't put it in a dangerously lean state either.

 

You had previously fallen for the marketing hype related to Octane. PREMIUM is NOT reflective of the Quality of the fuel. Octane used to refer to the relative percentage of an 8-sided molecule in the fuel, now, it's a "Research" number which describes how the additives and fuel ACTS like true 87%, or 89%, or 91% Octane fuel.

Depending upon what additive(s) is/are used to boost the fuel's resistance to premature ignition, MANY fuels labeled "Premium" are actually an inferior product compared to the fuel labeled "Regular" at the same pump station.

Also, a "hotter ignition" doesn't fix problems related to using poor quality "Premium" fuels. Hotter ignitions are most often used in colder-running engines, and vice-versa, if I recall correctly.

The only engines that require Premium (assuming there are not other problems, such as hot-spot tendrils from carbon buildup) are those engines with high compression. Otherwise, you're wasting money to use "Premium"...especially when oftentimes "Premium" is actually an inferior product.

The only times I've ever benefited from higher-than-regular octane is when I go to the low parts of Death Valley...the A/F mixture begins to lean out below sea level, and sometime that tiny bump up in Octane rating can keep a leaning engine from pinging...but, it's just a baby-aspirin bit of help for a developing jetting problem...it's not truly an Octane-related problem.

 

I have a sticker in the back of my owners manual that says premium gasoline only and that's all i've ever run with no problems. The sticker looks like something that was added after the printing of the manual becasue it must have been left out.

 

Interesting!!! BHeart thanks for the info. I think I will give regular gas a try for a while.

 

The manual says burn regular gas. I have had no issues with it even after going to the 351 which Bill claims to be 12:1 compression. No pinging here after 3200 miles of mine on the bike. (total 5400 miles)

I agree there is more power in regular gas when used correctly. Premium can help make more power but timing has to be changed.

Thanks for the air/fuel Info.

David

 

The label on the KLX says to use 91 RON fuel. Which really equals out to be Regular 87 Octane fuel at the US pumps. Next you fill up, take a look at the octane equation. It should look like this, " RON + MON / 2 ". I normally use 87 octane for daily driving or comutting. When I take the KLX off-roading, I fill up with 91 or higher. Due to the higher engine temps, contast changes in throttle & loads, and usually higher RPM's. And I have had the KLX engine knock before using 93 octane, I was pushing it too hard under a heavy load up a very steep grade hill.

As for spark ignition. You want a colder plug for high rpm driving and a hotter plug for slow rpm driving. The deal about this is to keep the engine when temp range. A hot plug in high rpm driving usually equals pinging. A cold plug in slow rpm driving usually equal carbon fouling. In winter, you can use a hotter plug to help warm-up the engine better. And in summer, a colder plug helps with pinging.

 

87 octane in my 351. No issues. I learned on this forum quite awhile ago that the higher octanes do not necessarily mean more power.

 

Did you measure the ambient temp each pull?