Sticky AeroInjector

[mike.smith]

Hey, all:

I feel like I'm posting issues all the time. But I'm getting ready for my fist flight and just need to make sure everything is as close to 100% as I can get it.

I have the newest version of the AeroInjector. In the past there had been some issues with slide bodies that were stikcking/jamming under load (air coming into the carb would press on the slide body and create excess friction). Sonex says the new AI's don't have that problem, but I AM having that problem. The throttle works fine, nice and smooth, when the engine is not running. As soon as the engine is running it sticks terribly. I can feel it jamming up at the AI.

I have a solid wire (not a braided cable) throttle cable, so it's not that.

I plan to open it up tonight to have a look, and see if there is some little particle or something jamming it. But if that's not it, what was the solution in the past for getting it to slide better? I know I shouldn't put any fluids or grease in there to gunk things up. I seem to remember people had polished some part of the slide body.

Thanks,
Mike Smith

[fjdoug]

hi Mike,
mine had metal in it.
not all but i think most of the metal came from making idle adjustments with the throttle closed.
the steel adjustment screw stops against the alu slide, my screw had a jagged end and turning against the slide scoured the slide.
i squirt a little LPS-2 into the carb whenever i have the cowl off and the aerocarb has worked well for me since.
Doug.

[MichaelFarley56]

Strange question Mike, but when your carb is sticking, do you have the cowling on or off? I've done some tuning on mine without my cowling and have seen a lot of condensation (even frost at times) form on the Y pipe intake tube just above the carb, and occasionally my slide can stick as well. I've thought of this as a possible issue with said condensation and things getting cold. When my cowling is on however, I've never had this issue.

If needed you can always disassemble your AeroInjector and make sure there's no debris causing issues. Finally, you've already said it but make sure your throttle cable doesn't have any sharp bends which could bind up the cable movement.

Keep us up to date on how final prep goes for your first flight!

[mike.smith]

Strange question Mike, but when your carb is sticking, do you have the cowling on or off? I've done some tuning on mine without my cowling and have seen a lot of condensation (even frost at times) form on the Y pipe intake tube just above the carb, and occasionally my slide can stick as well. I've thought of this as a possible issue with said condensation and things getting cold. When my cowling is on however, I've never had this issue.

If needed you can always disassemble your AeroInjector and make sure there's no debris causing issues. Finally, you've already said it but make sure your throttle cable doesn't have any sharp bends which could bind up the cable movement.

Keep us up to date on how final prep goes for your first flight!

I aborted my plans for a first flight by the time I taxied toward the end of the runway. I needed TWO HANDS to move the throttle forward! Can't fly like that.

It happens the same whether the cowl is on or off. I took the whole carb apart last night and blew it out with compressed air. There was no visible debris, and no odd scrapes on the delryn slide material. There was nothing of any note, so I put it back together. No change. Without air going through the carb, throttle works. With air going through the carb, it's like the carb slide is being held back by a circus elephant.

I'm going to try switching throttle cables, and rerouting the way Sonex does it (carb turned 180 deg so the cable comes in from front-to-rear (looking at the airplane from the side)).

[mike.smith]

I am going to try routing a new cable like (apparently) the factory Sonex have theirs run. That is, the AeroInjector is spun 180 degrees, and the cable runs the the front of the cowl and makes a single U-turn back to the AI. If anyone else has done it this way and has photos, I'd like to see how big the U-turn is, and how you keep it away from the hot exhaust pipe.

Thanks,
Mike

[SonexN76ET]

Mike,

I will send you a picture of my throttle cable routing and supports to keep it away from the exhaust. Mine is similar to the way Sonex has theirs set up. I was able to take a look at the Sonex throttle routing when I went through the factory flight transition training in April (I highly recommend this flight training). I will post my pictures Wednesday evening.

I am very glad to hear that you got your primary ignition working properly.

[SonexN76ET]

Side View AeroInjector Cable Routing

1.jpg (166.09 KiB) Viewed 7775 times

[SonexN76ET]

Another view of cable routing

2.jpg (143.71 KiB) Viewed 7775 times

[SonexN76ET]

Here are three pictures of the throttle cable and mixture cable routing.

[mike.smith]

Thanks for posting. Joe Norris posted some of the factory installation as well. The common denominator is the standoffs added from the engine block, to stabilize the cables and keep them from the exhaust.

Mike