[Rolf]

Hello,
My name is Rolf from Germany and i would like to convert my old 1978 Yamaha XS 750 to EFI with speeduino. I have done some research on what board to use. Right now im tending towards the NO2C for space reasons. My question ist this:

Since the XS 750 is a three cylinder bike is there a problem with this uneven divison? As the NO2C board only has 2 ignition and injection outputs one of the two outputs would have to do 2 clyinders and the other one only one. Will this cause any problems? Or is it better to use a normal size board like the v0.4 and put each injector/iginiton coil on one output? Because in the manual it states that for 1,2,3 cylinder engines each cylinder should get an own output on the normal size boards.

Greetings.

[moonie223]

You need a board that has three independent spark and fuel outputs. Sadly it's not a 4 cylinder with one missing, it's all different.

Engines multiple of 2 have two cycles that are always 180 degrees apart, so if you split the fuel injection pulse into two as to use one driver then you are squirting at a closed intake valve and an open intake valve. If you look at the cylinder sharing the output, it's the same but backwards. Since you are 120 degrees out this won't work.

Same with ignition, when you share a driver you spark at compression and again on the top of the exhaust stroke. If you aren't 180 degrees out this won't work, either.

[theonewithin]

You can use the NO2C with its add-on daughter board.

You can reassign one of the outputs on the main NO2C to do an extra injector output and use the extra IGN outputs supplied by the dB to get what you need.

Otherwise a 4x4 board will be needed or design a new one that has just what you need.

[Rolf]

Okay thank you for the quick answers!
Because this is my first speeduino project i first want to start with a already designed PCB that i only have to solder.
If that all works out i might start designing my own PCB .

[theonewithin]

Look at the UA4C.

Pretty sure it's the cheapest around.

Almost no soldering though.

[cheoman]

from experience better use v0.4.3. that way you have the outputs for each injector and ignition, I currently have my full sequential 3-cylinder engine with no problem.

[theonewithin]

from experience better use v0.4.3. that way you have the outputs for each injector and ignition, I currently have my full sequential 3-cylinder engine with no problem.

UA4C is generally the better option for a bike. Smaller form factor. More IO than 0.4 too.