Rodbolt, I need a reminder

[boscoe99]

Is it the number two spark plug that is made to fire based on the position of the crank position sensor, as opposed to the pulser coil that is firing numbers one and three, on a 90 HP two stroke?

If so, is this the reason that the SM does not show the CDI output for the number two coil when the motor is being cranked?

Is there any particular reason for this methodology being used? Do other models use it?

I wish that I had paid more attention in the school house.

[99yam40]

And while your at it what does unplugging the emergency circuit yellow wires at the CDI bypass/do to get the motor to run?

[rodbolt17]

depends on the model84-91 the pulser sparked 1&2.
92 up and the pulser sparks 1&3.
unplugging the yellow wire places it in bypass mode. the timing is fixed and one cyl is lost. but the other two will spark off the pulser coil.

[pstephens46]

Rodbolt's on FIRE today!

[99yam40]

so it sounds like the bypass mode does away with the input of the crank sensor and lets the 2 pulser inputs to fire the 2 cylinders tied to them at the timing they are physically set at . My guess anyway

Boscoe, I think that the crank position sensor needs to spin at a certain rate (RPM) for the CDI to recognize it and create the 3rd cylinders spark and also adjust timing.
so cranking speed is not going to fire the cylinder that does not have a pulser coil

again just my thoughts

maybe Yamaha was saving money by removing one pulser coil.
My C40 has 3 , one for each cylinder. seems so simple they needed to complicate it on the 90

[boscoe99]

There is so much variety in Yamaha designs that it would almost appear as if many different groups within Yamaha designed various models. And that they did not talk to each other.

[pstephens46]

There is so much variety in Yamaha designs that it would almost appear as if many different groups within Yamaha designed various models. And that they did not talk to each other.

Somewhat typical. Many different COMPETING groups...
Good and bad....good for innovation, bad for mechanics. Every now and then someone hits one out of the park.