Just putting 100 octane in the tank without changing the timing will do nothing...and if you change the timing to run on 100 octane, it will not run on pump gas without detonation. IMO 11.8 to 1 compression is too much for pump gas.

 

My Triumph Street Triple has 12:1 compression and it works fine with pump gas - even had a couple of tanks with low octane.

 

Apples and oranges..the triumph has a "knock" sensor that automatically adjusts the timing to match what ever gas you put in it.

 

So do our Harleys (although it may not work very well with a non-stock motor).

 

Wouldn't the new map correct it?

 

Correct, assuming the timing is correct for pump gas as it is now. And if it is, my opinion is that a lot of power is untapped because of the timing being backed off enough to get the thing to even run without detonating given the CR.

I share your opinion on the CR being too much for pump gas. That motor will have to be run at way less than what it has for potential. At the very least, it will need octane booster, or a mix of race gas and pump gas. That rarely ever works out consistently though.

There's never a "magic pill" cure. If it were me, I'd build the motor to run on the fuel I intended to use.

 

That sucks that your numbers aren't where you wanted them to be. How was your experience with Brian?

I do have to agree that that much compression without a boost in octane will keep your timing backed off far enough to seriously affect your total power. Everyone looks to cams, heads, injectors, etc and tends to overlook how much power can be gained by proper ignition timing. Even in the threads that I have read over in the tuning section, everyone is so concerned about the fuel map and fattening it up but rarely does anyone discuss timing. I don't care how much more fuel you have in the cylinder if your not lighting it up at the right time it's not going to burn correctly. If you don't burn all of the fuel and air (that you spend so much money on parts to cram more of it in your cylinders) then you will never reach your potential for power. Usually your cam manufacture has recommendations for ignition timing, may see if they have any information and compare it to what you have now

 

Timing tables can be changed, but I haven't heard of an effective way to recalibrate the detonation sensing system (other than being able to turn it on or off). If this is incorrect, someone please correct.

The Harley ion-sensing detonation sensing system is factory-calibrated by using sophisticated sensors and equipment on a highly-instrumented typical stock sample engine. Changing things in the ignition system or conditions in the combustion chamber apparently throws it off. Harley may provide altered calibrations for specific combinations of factory parts they've tested, such as their various HD branded "stage" offerings, in their downloads for these stages, but I don't really know.

Apparently, the system works quite well if the engine remains completely stock, but when the engine is modified, it often retards the timing when it isn't necessary, because it decides that detonation is present when it really isn't. Alternately, when things like aftermarket coils and plug wires and spark plugs are substituted, it might not detect detonation when it really is present. More conventional acoustic-type detonation sensors can easily be fooled too though, by making changes from stock.

 

A lot of guys have successfully run pump gas in high CR motors, that is true. However the OP was talking about peak power levels being down from what was expected. Another thing to consider is that water cooled engines are not as prone to detonation as air cooled motors are. The head temps a quite bit higher in an air cooled motor.

Case in point, although not HD, the two are closely related in behavior, my air cooled VW drag race car. turbocharged 142 Cu In. 10-1 CR. On methanol, I can run it in excess of 30PSI boost. I have not done that yet. But at 20PSI boost it makes well over 500hp.
Take that same motor, put in pump gas and alter the timing and fuel curve to maximize it's use. Only 8psi can be achieved with a resultant power level of 320hp before it starts rattling from detonation.

So yeah, you CAN run low octane fuel. Just don't expect maximum output.

 

Thats along the lines of what I'm thinking. When I first replied to the OP in another thread he was looking for a tuner(person) that was familiar with the SEPST. I have the 2012 version of that software, unless they have changed something in the newer releases, you go into a menu of maps and select the one with mods similar to what you have done to your bike, load the map in your ECM and then tune it from there. If the ignition timing requirements for the OP's cams are significantly different than a SE version of a cam with similar specs and his timing tables were not modified from the original tune there could be a potential problem.