912 Tach Pickup

I am having a little trouble figuring out which wires are my tach wires. Looking at the rear of the engine I have 4 pickup coils. Some of the wires had been cut before I bought the engine. Facing the rear of the engine, the bottom coil on the left side has two wires which were cut. I found two matching cut wires in the braided sheath running from the top left coil to the ignition box. I spliced them back together. The were matching colors and tracers. The only other wires coming out of the engine are the two red ones which I think are the ignition circuit charging coils. I guess my question is which pickup do the tach wires come from and am I missing a pickup? Should I have 4 or 5?

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Originally Posted by cainbird

I am having a little trouble figuring out which wires are my tach wires. Looking at the rear of the engine I have 4 pickup coils. Some of the wires had been cut before I bought the engine. Facing the rear of the engine, the bottom coil on the left side has two wires which were cut. I found two matching cut wires in the braided sheath running from the top left coil to the ignition box. I spliced them back together. The were matching colors and tracers. The only other wires coming out of the engine are the two red ones which I think are the ignition circuit charging coils. I guess my question is which pickup do the tach wires come from and am I missing a pickup? Should I have 4 or 5?

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Might be good to refer to the Rotax manual on what each of the wires is for and which positions they are in the connectors. Check this manual, starting on page 108.

http://www.rotax-aircraft-engines.co...kus/d04631.pdf

I have a 912UL and a 912ULS in my hangar and both have tach wires originating from a pick-up coil at the three o'clock position (observer looking aft.) The two wires are incased in a rather thin black sheith. The wires are white/blue and white on both. Drop a note if you need further help. I just went through this on the UL, as the wires were cut there as well. The ULS was factory new.
Lowell

Thanks Guys, any way you could snap a picture of the rear of the 912ul engine HighWing, or is it already mounted on a plane? I have 4 pickups total and think I should have 5. 4 for ignition and 1 for the tach. I cant find a picture anywhere online of the back of a 912. Cain B

I will attach four pictures of my new project and hope they help. (the first image is out in cyberspace so it is attached to a succeeding post) Keep in mind that I am under construction and that the engine mount is my design so don't look to that for reference.

The first image (next post) will be the tach lead. The image is from a level perspective from the right side of the engine observing from the front. you will see the blue and white wires that lead under the point where the metallic braid sheild begins on the wire from below passes to the cluster on top.

The second image is taken from about a 30° above horizontal perspective. It shows two shielded bundles exiting the forward edge of what would be the flywheel shoud and a snipped of the shielded wires seen in the previous picture. The bottom cable of the two runs aft to the voltage regulator. Note the serial number plate for reference.

Image 3 was taken from about the 60° position above the horizontal. It shows the top wire cluster and the adel clamp securing them. The hint of braid to the right is the engine to ignition module ground strap.

Image number 4 is from the opposite side showing the top adel clamp from the passenger side and the cable run to the ignition module.

hope this helps,

Lowell

The first image is somewhere out there. I will try again.

Lowell, thank you so much. That is a great help. I think I have it figured out now. What a great site and a great group of guys we have here!

Thanks Again~Cain B