Aero Carb Tuning

[Aldo]

Hello Everybody,

My new to me Sonex is running rough and rich. The previous owner mentioned he had tuned it rich using a no. 4 pin. Everything I read, however, indicated that the factory installed no. 2 pin works well in most climates. Being in coastal NC, I would consider our climate pretty average. So, I am thinking of going back to the no. 2 pin.

Are there any tips or tricks anybody can relate to help reduce tuning time and cycles when I install the no. 2 pin?

Thanks!

[mike.smith]

Hello Everybody,

My new to me Sonex is running rough and rich. The previous owner mentioned he had tuned it rich using a no. 4 pin. Everything I read, however, indicated that the factory installed no. 2 pin works well in most climates. Being in coastal NC, I would consider our climate pretty average. So, I am thinking of going back to the no. 2 pin.

Are there any tips or tricks anybody can relate to help reduce tuning time and cycles when I install the no. 2 pin?

Thanks!

I would go ahead and try that #2 needle, and follow Sonex's instructions to the letter. That's the best place to start. You could go slightly rich to start. If the temps are up then you may be too lean and need to richen. For me, I did need to move to the #2.5 needle and then everything ran great. But everyone's experiences are different.

My experience, and that of some others, is that the needle carrier threads may be loose, and so turning the set screw down against the carrier may cause the needle to move forward and lean out. If this is happening Sonex suggested dulling the threads of the carrier slightly with a hammer, to create some extra friction with the AeroInjector (AI) body.

The only "sure" way I have found to be totally precise, is to remove the air cleaner so you can look up at the needle. Mark it with a Sharpie right where it enters the hole in the AI. When you turn down the set screw, make sure that line does not move. If it does, back out the set screw, reset the needle, and try again.

[SonexN76ET]

Aldo,
You need to exercise extreme caution here. You are venturing into a very high risk area in attempting to perform maintenance and modifications as a new owner of an already built experimental aircraft. If you had purchased a Cessna or Piper would you consider fiddling with the mixture settings on the carb or injector?

I know of at least two incidents where second hand owners are dead because of making changes to their AeroInjectors/ AeroCarbs without fully understanding what they were doing.

If I were you I would find a Sonex builder in your area and get some assistance with tuning your AeroCarb. The other builder can show you the ropes and what to look out for. I am certain that many builders would welcome the chance to help you.

If you choose to go it alone, please test the plane on the ground before you fly. Follow the manual to the letter. Don't hesitate to reach out to others if you have questions.

Safety First!

Jake