It's interesting to note that the exact point of beginning to open the secondary throttle on your graph at 7,000 rpm perfectly coincides with the 7,000 rpm "dent" in my dyno test graph.

Thanks, Nigel. You supplied a useful piece of information which points to the likelyhood
of that dent being removed along with the secondary throttle plate.

 

That is pretty much what I am planning except I will be setting the bike up with a temporary wideband O2 and run through all operating ranges and dial in the map on the street. I may look for a dyno to check the change (I know that would be interesting for people to see and to verify the change).
No timing adjustment capability for the 300 dual sport from dynojet. All of the CDI components are internal to the ECU. The 300r uses inductive ignition, easy to modify (for an electronics engineer) with a piggyback controller. The CDI in the ECU would require a flash tune.

 

NP, I plan to remove the plate, if you get to it first let us know what you find out, I will do the same.

 

Let me remind you two that you CANNOT remove the secondary throttle plate until you have the tools and the talent necessary for an immediate "slow and safe" reprogramming of the entire open loop fueling scheme.

BTW, this also means: Never remove your O2 sensor or tamper with its' functioning UNLESS you have a method to slowly/safely reprogram the entire fueling scheme

 

Good advice.

I like the O2 sensor as I ride closed loop (3,500 - 5,000 rpms) the vast majority of the time, and am rarely in open loop as it's not required for normal transportation riding. I made a little hole in the torque extension pipe so it can continue to sample the exhaust gasses as they pass by.



From comparing the graphs, the secondary throttle plate appears to be closed MORE than the primary throttle plate is open ONLY at about 7,000 rpms where it just begins to open past 50%, creating that "dip". It's imposslble for it to let any more air into the engine than the primary throttle plate does. It can only act as a restriction over it, however briefly at that point.

 

Will do.

I'm not exactly sure when as my bike is in constant daily service. I still haven't yet installed the mixture enriching resistor in the IAT either. I'll likely do both when I have everything apart.

 

I appreciate the warning, I have done efi tuning exercises before. The PCFC is extremely easy to use and understand. It would be extra slow without a data logger, but can be safely done with a WBO2. If it was all simply remapping than I would not be hesitant, I am more worried about unintended consequences that may cause something else to operate outside it's programmed range. I have no idea how sophisticated this ecu is, so is something else going to operate outside it's programmed range if the secondary throttle blade removed. My guess is that an O2 delete would be all that is needed to be able to remap. Other things that may be effected would be idle speed, throttle response, part throttle cruise characteristics. Don't know, have to have an appetite for experimenting. But if the ECU throws a code that can't be resolved then everything is going back. That would be a PIA.

 

I is likely that removing the O2 ( without plugging in a O2 delete device) or the secondary throttle mechanism would throw a code.. Only the actual throttle plate itself should be removed, leaving the shaft and all other components in place.

CLOSED loop fueling ( and ops) would need time to adjust (from the trims).. Closed loop fueling would be horribly flawed, based on the assumption that the voltage log is indicating that a max of 54% throttle is all that is allowed up to approx 7k RPM AND THEN slowly works up to 100% by approx 9k RPM..

 

I thought closed loop was adjusted by the O2 sensor, and that open loop was preprogrammed by the ECU. Maybe I have had that backwards all this time.

 

That is correct, closed loop is using o2 feedback. A possible consequence of removing the throttle plate is it could exceed the fuel trim range for the o2 correction. Most OEM systems that I have seen, the max fuel trim for o2 correction is between 15% to 25% from the base fuel tables. It is also a slow correction. Where the secondary throttle is doing the most damage is right at the 6 to 7.5K range, removing it would require a heavy correction there along with adjustments everywhere else. A little frustrating to see that intentional handy cap right where a trail bike would benefit most. It is too cold here to do anything for a few months, so I can mull it over for a while. A flash tuner would be awesome right about now. I am guessing the D-Tracker API Tech ECU would work on the 300, but what a PIA that would be setting it up.

I may be overthinking this, but part of my concern is what else is driving the secondary throttle position. For a given main throttle position, do you have multiple secondary throttle positions based on other inputs, and if so does that mean you have multiple fuel schedules corrections for a single main throttle position. If so, it will be impossible to have a dialed fuel map if the ecu is "moving" the secondary throttle and getting feedback, but it is no longer there. I was only able to check it at wide open main throttle on a very cold day. It may not be that complicated. I would bet that a stable idle disappears though, the secondary valve is like 80% open when you first start and then closes progressively as the bike warms up. I wonder if anybody with a new 300 has done this? This could turn into a next winter project for me, as my main goal is to do a bunch of riding once the weather gets nice. Sucks though knowing that I am loosing 5 hp at 7k rpm.