When I first read about the E throttle I thought the first thing I would get rid of with my SERT is the throttle progressivity.

For those who came in late at low revs the throttle twist grip setting isnt followed exactly. If you open the throttle 100% at 1000 rpm the throttle valve plate opens 23%. If you open it 70% at 1500 it only opens 39% - see attached table.

In the help file it says these settings help stop the engine bogging down at low revs. I was skeptical that this was a good idea, I wanted the throttle to do exactly what I said.. So I dialled this out, set all the values to maximum so that the plate follows the wrist - so 55% throttle at any revs is 55% etc...

And she ran like a dog. Bogging down when trying to launch at part throttle, coughing when blapping the throttle. So I have put back the original settings.

Has anyone else played with this setting? Did you get the same result? Any idea why an engine with cable throttles doesnt do this??? Is it something to do with having big cams??

 

Perhaps the fuel delivery is related to rpm, and not throttle opening? Thus with "your" throttle setting, at 1000 rpm, your plate is now wide open, but still only getting 23% fuel?

 

A lot of carbs have been that way for years.CV's they are called.
Big Block

 

Also I would think that the fuel injectors would need to be larger to deliver enough fuel for WOT at 1000 RPM.And you would probably have to back the timing down to 0 degrees or just before.Large cams kill low rev performance.
Big Block

 

His bike is injected...

 

When you suddenly open the throttle plate to a wide setting at low RPM the venturi velocity drops way off. That sudden momentary drop in velocity reduces air flow and volume going into the cylinders but the injectors throw a charge based on RPM and throttle position so the A/F ration is momentarily too rich. Delaying the rate at wich the throttle opens keeps the the venturi velocity up providing smoother throttle response.

When I was learning to drive a car (back before constant velociy carbs) my dad told me "don't give it the gas any faster than it can take it".

 

It's a fly by wire computer thing linked to epa somg sh-t, and accelareator pump action signal to fuel injection control unit. You can change it a little----I think a few percent one way or the other.

 

On these TBW bikes even though you have the grip wide open the throttle blade will not be at 100% until you are at around 3000 rpm. That is why on these bikes when tuning you calibrate 100% throttle from 3000 and cable bikes from 2000 rpm. You can max out the throttle blade control in a certain pattern and increase response. You have to be carefull and work in a pattern. Kingking, is that the table before or after you you adjusted it? It looks close to what I do with the TTS, but are some of those cells maxed?

 

I moved the throttle progressivity tables to be 1:1 using the SEST. If the throttle was in the 50% position I wanted 50% throttle. If it was 100%, I wanted 100% regardless of rpms. My throttle response is now exactly the way I want it vs the way the engine designers set it to protect the engine by not loading too much torque early on.

I like the immediate response I now have but it's important to note that I have a larger TB, larger injectors and headwork so my outcome might be different from others. As the tech explained to me, HD built progressivity into the low rpms to mimic the slack or stretching that occurs with a cable operated throttle (whether efi or carb).

By providing these tables, they can give the bike a similar throttle response for guys coming from older bikes that have a hard cable connection from the throttle.

From my perspective, I figure since I have efi and an electronic FBW throttle, I'll learn to make the decision about how much throttle I want or need vs letting a computer and engineers in Milwaulkee make the decision for me.

I definitely prefer the responsiveness of 1:1 in my throttle vs the progressivity but my guess is that its not for everyone. Essentially with 1:1 in the table, the rider now becomes responsibility for managing a smooth acceleration vs relying on the computer.

 

Did you actually read my OP?

I did the same as you and it ran like crap, bogging down when trying to launch.

I suspect jimsreddyna is on the right track with the velocity being the reason it better to open it less at low revs.

But I still cant explain why a cabled bike doesnt bog down....