I put a few tanks of terribles 100 octane in the boat when I was at parker, and read the plugs - it was a hair on the richer side deemed pretty close to perfect. ran well.

After playing in parker on memorial day, the following weekend in havi, I still had one tank with some 100 in it, but put 91 in both tanks at fill up. Basically one tank with a mix, then one tank with pure 91 (AZ gas).

The next morning, I went out for a tune. I lost a little more than 350 rpm, with nothing else changing. Reading the plugs, it looks a little lean now.

I am wondering if it is the octane, or possibly oxygenated gas causing the issue. This is the first time I've tried to run anything but pump gas, just wanted everyone's opinion.

What you are seeing is super normal, the engine on the 91 is actually not only getting less octane (burn rate) but also getting less fuel.....Oxygenated or alchohol fortified fuels are harder to move, therefore with the jetting really close for the higher quality non emmision ready fuel, you were running "Stupid Lean" with the 91 AKI.

You really need to get to a happy medium with both fuels if your going to switch back and forth, this is why typically run some Rocket it the 91 on my jet, I get the best of both worlds and don't have to carry 100 gallons of race fuel around with me.

I get the small drums of Rocket 102 and mix it 25% with 91 or 92 AKI pump stuff...

Jet it accordingly and away you go, no where near as lean if I switch to just pump gas...

I used to have a Weber adjustable plate in my jet but it has a problem, you could adjust the mixture from the driivers seat like a Dial a Jet. I don't think they're made anymore...

edit;, think of pump gas like methanol, it takes roughly twice as much fuel for the same amount of energy as gasoline...


GT

That's a great arguement for jetting the primaries for 91, and the secondaries for 100.

I noticed on the 100, the more throttle I gave it the faster it went.

On the 91, cracking the secondaries only made more noise.


I have my hand throttle set so 0 - 90 degree mark is primaries only, and anything past 90 degrees is on the secondaries.

Since I'm going to Big River next week, where in Parker did you get the fuel? Gonna load up the Moo on the good stuff (She had full tanks of good stuff 3 times in her life, once , and first, twas her trip to Temple Bar)

She runs ok on 91, really likes 93, but the 102 she's had a few times she LOVES!

Ray

Ok, Yeah, been there a couple times in the last couple weeks. Didn't pay attention to the pumps! lol

Ray

if you need leaded (i think its leaded dont quote me on that) get the 110 AV GAS($4.xx) at parker oil. last time i looked it was cheaper then terribles 100($6.00).