Hello.. I just sat and read all 24 pages and it is a fascinating read!
I am in Ottawa, Canada and am about to set out on my own two-stroke efi project.
I have a 1976 RD400C completely stock.... just the way I like them. They arent horse power machines in stock trim but they are fantastic for cruising around town. Id never mess with intake or exhausts or porting because I love the torque right in the lower and mid rpms. Yamaha says 40hp stock but I suspect it's really 35 or so.
At this point I have purchased a Microsquirt because it comes in a small sealed unit with water tight amp seal for the wiring harness. I plan on not only controlling fuel but also ign curve. I'll need more power for fuel pump so I have upgraded to a VAPE ignition system. It produces 150 watts and now the ignition is CDI with a VR sensor. There is no ECU in this setup... I have it set at a static 20 degrees (2.3mm BTDC on this bike) The microsquirt will be able to take direct control using the VR as a signal in and also will also directly control the ignitor circuit in the CDI/coil. Microsquirt can log two EGT channels so I have also purchased those. I will also have a CHT sensor under one of the plugs to be used for start up enrichment and also logging purposes. I have a heated Wideband O2 sensor that I will use as well but as we know... the readings may not be an accurate picture of what's happening in the combustion chamber. An intake air temp sensor as well.
First thing in my plan is build a hydraulic gear pump dyno with a needle valve to control rpm. I have everything needed and will soon start welding a frame to hold it all together. The plan is make it so it all fits between the swing arm rails and the stock chain will drive the gear pump. The pump will be able to rotate a little... there will be a 12inch arm attached to the pump and it will press a load sensor that will also feed into the microsquirt and be logged. I will trick it to think it is something else but it outputs a 0-5v signal so thats what matters. I have two stepper motors... one will manage the needle valve and the other, the throttle cable. I have written but not tested code for the Arduino to go to a specific throttle % and hold it there while the one controlling the needle valve will use engine rpm to open/close the valve in small increments to keep the engine at desired RPM.
The plan.... set arduino to hold certain cell value on fuel table and matching cell in spark advance table then I will monitor EGT and O2 and torque produced as I add/remove fuel to achieve good power but safe power then I will add/remove spark advance as it plots the torque curve so I can see where it makes the most power then remove a couple degrees to leave it on the safe side of things. I am thinking about installing a knock sensor to prevent me from destroying the motor during ignition tuning but its an air cooled motor covered in fins and there is no where to really put it... plus I dont want to weld anything to the engine. However... it is my understanding that high octane pump fuel will deter knock and allow me to advance spark enough where I will see torque production drop off a little without actually knocking. Then I can chose the part of the curve before the peak and set the timing there. Lots to learn and loads will go wrong but im hoping to see just how strong a stock setup can be. Also hoping to tune it to be a smooth ride with no surging or bucking etc. You can never tune this out of an RD400... i have mine pretty damn good but i have a really rich low rpm do achieve it. smokes like a chimney at idle.
I am planning on Alpha-N as I ran a vacuum signal test run the bike with the carbs and it looked like a jagged saw tooth. Completely unusable. I used the oil injection nipples on the carbs to get the vacuum so.... maybe when the R6 throttle bodies are on the bike that have actual vacuum ports it will perform better. Testing will tell. I also have ITB control method which is method that uses Alpha-N and switches over to VE assuming the signal is more consistent in higher rpms.
I love what you are doing here... just wanted to introduce myself and share what I have planned. I'll pop in from time to time and share anything I have learned
-John
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