Okay, Rhubarb, I'd like to pick your brain some more. Got my Rush mufflers Thursday, PCIII and K&N yesterday, and all has been installed. Reset the 0% throttle which was way off, first when cold, then later when hot--no change. Bike runs great, and much better than before. Jamie set the cruising range (20-40% throttle, undisclosed RPM) for optimum gas mileage yet without causing unnecessary heat.

Now, I'd like to play around with this "cruising range," which I would say is 20-40% throttle and 2200-3000 RPM's. The low RPM number is about as low as I'd probably cruise, and I can't see going >80 mph on a regular basis. I'd like to set it even leaner than it is now, and I would think too lean would be at the threashold of surging. I would also like to pump some advance into this range, which should increase mileage and decrease heat, and I guess that would be a point where the engine starts detonating under load. If I understand this, you can select a range on the notebook computer, then hit <pgdn> or <pgup> to change the entire range in units (Jamie's description). So why not select the range I mentioned above and knock it down a couple of notches at a time for A/F, up for advance in the same range. Then when it starts detonating, bump it up a percent or two. That would seem to optimize it for the gas I choose to use (93 octane).

Any of this sound like I'm sort of on track here? I'm a newb with the PCIII, but not computers, so I should catch on to this (theoretically). For your bike, you said you will "try to lean it out some in the cruise range," so when you do it, could you provide detailed instructions? I'm really interested in optimizing this new '07 SG for mileage, yet have good performance when I twist the throttle and want to pass a truck.

I've noticed that when I twist the throttle now, when it approaches a point presumably outside the leaner "cruising range" programmed by Jamie I can really feel it kick in, sort of like the secondaries of a four-barrel carb, a noticeable yet smooth transition.

 

You said exactly what I'm going to do. My only concern is that I don't know how lean I can go without causing a problem.
I'd guess that anything over stock is good, since it's not under load when cruising.

I don't know much about adjusting timing... When I worked on cars with distributors, we did it by seat of the pants and pinging.

I have marked the throttle in relationship to the brake reservoir when cruising at 55-75.
Now I will power up the PCIII with a battery and find out what percentage throttle it is when in that range.
Next will be to figure out engine RPM's in 5th from 55-75.

Then I will have my range to adjust. I'm down about 12-15% on Fuel Economy right now. At 20% throttle at 2750 RPM I'm 14% over stock. I think that may be the area to mess with.

As soon as I can figure out how to know if I'm safe without a AF Meter I'm going to play with it. Can anyone recommend a way to adjust timing or some basic changes? Performance is great, I just want some distance back.

 

Your mileage is going to be somewhat low w/a PC111.What your trying to do may get you the results wanted but may take awhile to fine tune.Your bike will see the ping before you will hear it.Why not have bike dynoed to your type of riding or for mileage increases?

 

I could, but what fun is that?

I probably will, although I am happy with how it runs just not the mileage. If I spend $300 to tune it to get 5mpg more, it will take forever to recoup that money. Really it's about distance per tank more than the money, but I still think about cost/benefit.

If I can make a simple change that gives me back 5-10% and it costs me nothing then I'm OK with that.

 

Man this is all interesting but confusing as hell to me, and have'nt got mine yet.

 

When you see it, its not so bad. It just sounds confusing.

 

What worries me is that with the PCIII and the '07 closed loop system, both O2 sensors have been eliminated, which means it has been changed from a limited closed-loop to full open-loop arrangement. Therefore, any intake or exhaust changes will not be "seen" by the EFI. So if you zero out the "cruising range," meaning the PCIII is using the values given by the EFI, you're probably too lean. With the stock air cleaner and exhaust it was very lean, and opening up the system with a new muffler and intake will lean it even more. So I think these values need to be >0, but the question is how much. I don't recall what mine are, but I didn't see much of a pattern, the numbers going all over the place as RPM's and throttle changes.

I think if it is detonating lightly at cruise, it'll really be audible as you apply load, so I think the goal might be to tweak it until you get no detonation under load at these RPM's.

My last bike was a '96 RK with an Andrews EV-13 (mild cam), DynoJet Thunderslide, and Crane HI-E4 ignition. The Thunderslide allowed the carburetor slide to ride lower than stock, thus lowering the needle and leaning the mixture, which resulted in about 20% better mileage for me. I was getting 50-55 mpg in touring trim riding backroads, so with this kind of mileage I'm going to be hard to please with this new SG. It won't do this well under any conditions, but my quest is to get the most out of it. In addition, on the old RK the Crane ignition module had 10 advance curves, and I was using the highest (most aggressive) setting that allowed more advance at part throttle. That combination resulted in great mileage, cooling, and performance as long as I used premium gas. Switching to 89 octane would bring on detonation under load.

Ignition advance in copious quantities at part-throttle is a good thing as long as there is no detonation. You recall the old vacuum advance mechanisms in pre-electronic-ignition cars, which allowed perhaps 20 degress of advance when vacuum levels were high, i.e. under light load (cruising). As soon as the throttle was applied the vacuum and extra advance decreased, hopefully before detonation occurred. This resulted in higher mileage and cooler engine operation. This is what I think can be accomplished with the EFI by replacing a vacuum value with throttle position. As throttle is opened in the older system the vacuum decreased in relation to engine load.

A/F ratios and ignition advance work together as they relate to detonation. Higher advance and leaner mixtures both promote it, and the ideal setting is just before incipient detonation.

I think marking the throttle is a good idea, but couldn't we just turn on the ignition without starting the engine to get a reading? Your ride is a Deluxe, so you have no tach, but I believe the gear ratios are the same as my old RK, or close. At 60 I was turning 2400 in 5th, so you can figure the other speeds accordingly.

Well, I was getting around 43-44 for the first two tankfuls on this '07 SG, riding backroads but varying the speed

 

Wow, a lot of info... Thanks!

The part about marking the throttle is:
I don't know how much throttle I am using at cruise. It seems that the throttle is progressive, not linear.
I marked the throttle position, because the PCIII will tell me what position it is at when I turn it... if I do this with a 9volt battery its easy. Using the marks to go by, I can figure out what range of position I need to adjust. Going by your numbers of 2400 @60 I know where to go in the rpm.

Now I just need to figure out how lean I can make it.

Here is my map... I'm thinking I can reduce everything from 2250 to 3500 rpm @ 20 and 40% throttle by some. Maybe as much as 50%?

I have no additional ignition advance at this time. I think the knock sensor will kick in before I hear any pinging, but I could be wrong.

 

Anyone know if Fuel Moto ever has special sales on the PC III's? Am looking to get one soon but will hold off if it will save a penny or two.

Ride safe,

 

I don't expect to see them discount them over what they already have. From what I'm seeing they are not having any problem selling them.
The list price for a PCIII USB for an 07 is like 399 right? Jamie sold mine to me for 291 shipped to my door.

lp