The last thread about who uses what octane caused me to conduct a test. The last couple tanks being nearly completely dry I decided I would try running 89 octane (sorry, could not stoop to 87) to see if there was a difference in mileage and performance. At first the bike ran fine and the mileage seemed to be right about the same as with 93. Then Friday I was on my way home from a job, left being very comfortable in just a T shirt and jeans but soon saw dark clouds so pulled over, put my HD Hi Vis rain gear on and the rain sock on my Heavy Breather. Shortly afterwards the rain started and very hard at times. It was mostly all interstate the 200 mile trip. Well after being in heavy rain for a while my bike started to run miserably, mostly when I had to lean back on the throttle to get around a truck. The bike spit and sputtered for a few seconds each time until it finally kicked in and took off. First of all my bike is an 01 without EFI so the newer bikes may react differently or not at all but I can say without a doubt that I will never again run anything less than the highest octane I can get. I should finish by saying I have ridden in the rain hundreds of times before without this happening.

 

I would think pinging would happen if anything.
I think you got some water in the intake.

 

Sounds like the intake took in some water or was partially suffocated by a soaked sock, but that being said, I want to try the same experiment but with 87 octane (regular gas). I'm not a big believer that the higher octane fuels give you better gas mileage or burn cleaner. I do believe that some engines are set up to run correctly using the higher octane fuels, but, whether or not you could get away with it would be a different story.

 

I don't believe 'Octane' had anything to do with your problem, prolly got some H2O in the fuel system. I run 89 all the time and get great mpg (48-50) all the time. Road home in the rain yesterday from a 117 mile ride.
the HD heavy breather will do that.
JMHO

 

I agree with everyone else that the octane had nothing to do with your problem.

 

The fact that this was a heavy rain condition is way too coincidental. The sock got saturated and you took in some water is my guess.

Run several tanks of 89 and 87 under normal conditions and this will give you the best appraisal of it's effect on the motor. If your compression is high enough it will ping, indicating predetonation which is what high octane fuel is designed to do - slightly retard ignition of the fuel and prevent early detonation in the cylinder prior to the proper time in the compression stroke.

High octane fuel has nothing to do with cleanliness or quality, it's all in it's ability to prevent early detonation in the cylinder due to high compression.

Any (or at least most) name brand fuel has a good chemical package with detergents, etc regardless of octane. Different gas stations have varying chemical additives in them. All the gasoline comes from the same plant/refinery, it's the additives that are put in it by the company at the station that varies.

 

The fact that it was raining invalidates your test results. Try it again when it's dry out.

 

I'm still running regular 87 octane for the last 3K mile in my '10 Road King 103" Stage ll. Got 43 mpg on this last fill up.

On my '09 Super Glide 103" Stage lll I've run regular 87 octane for 10K miles and as a 96" it ran on regular for 16K miles for a total of 26K miles without any issues down here in South Florida.

It maybe that fuel injected Harleys is what makes the difference over the carb ones in accepting lower octane fuels.

 

...sorry, but your little test is like saying..I decided to try a cheap, no-name brand tire on my Indy 500 car one day....as I came out of the pit and onto the track...it started pouring out..next thing you know...my handling is crappy....must be the tires

 

I've tried running regular gas, around town and cruising up to 60mph its ok, but above 60, or passing, it sucks, and that has been my experience with the past two bikes, I don't run nothing but premium now, I've had enough testing.