SonexBuilders.net

I purchased a Sonex with about 65 hours on it and it barely ran on the secondary ignition. After many timing adjustments and troubleshooting everything, I finally replaced everything and all was good....except for the high CHT. I needed to retard the timing and was still frustrated from all the adjustments I previously made before I replaced everything, so I fabricated a tool to help me dial in the adjustments.

I basically cut two equal depth grooves on each side of the magnet rotor and 3D printed a dial to slip over it when making the adjustment. It makes it easy to see how much of a movement is made and easy to hold in place while tightening. I've attached some pictures.

I wish I had this when I was originally doing the troubleshooting because I was always second guessing where the rotor was set at since it is so hard to see. Now I know exactly where it was at before making the slight adjustment.

Just thought I would pass this along.

https://imgur.com/a/bC1Ell0

The dial would solve one problem. My bigger problem has always been the trigger cap (with the magnet) has a LOT of play, so it hits the black pickups on the stator assembly. I have to do a LOT of trial and error spinning the prop/crank in 90 degree increments to not only get the magnet in the right place, but to make sure the trigger cap does not scrape one or both of the black pickups. I put a thin piece of cardboard between the two but it's hard to do that AND get the angle of the magnet set. If you tool can solve that scraping issue then I'll buy one from you in a heartbeat :-)

I have not had an issue like this, but I can see how this would be a problem. I originally had the black magnet cap which had a pretty weak magnet. I ordered a new cap which has the stronger magnet, and it did have a lot of slop when mounting to the 10 amp post and trying to adjust it. Shortly there after I upgraded to the 20 amp alternator and all the new parts fit nice and snug. I don't think there will be any issues adding a piece to the tool that would help correct this. Do you have any idea how thick the cardboard pieces you used were? These things are pretty easy for me to make, so I can make one with 0.5mm and one with 1mm and you can try them. You don't need to buy them, I'll just send them to you. Also, I have an extra, new style - red cap, since I bought one and one came with the 20 amp upgrade kit. I can send that to you since it has the alignment grooves I machined into it, but I ask that if you like it and decide to keep it, you need to send me your existing magnet cap so I can make another set for someone else to use. It'll be after Thanksgiving before I can print those and I'll need your address.

I posted video on YouTube showing how to use this timing tool.

https://youtu.be/4hAo_dGEyF8

Andy