I'm having a couple issues with an Evo 52 (2 stroke) and after trying to resolve them myself I'm breaking down and asking for help. First, the high end needle won't stay still. When you turn it it is very loose and when I run up the engine it rotates forward (richer) until it hits the little arm that's supposed to help you tune the engine. Is there a way to tighten this so it doesn't "auto-adjust"?

Second, this engine has the remote needle so the high end is in the back and the low end is on the carb. The low end has limiters as to how far you can adjust rich and lean. I have it so lean it's almost closed, maybe 1/8 turn open and it still seems to run rich. This has led to 2 deadsticks. The engine may run fine on teh ground but as soon as it gets on the runway and up in the air the engine dies. Idles ok but when you push the throttle forward it stumbles and may eventually go WOT. Eventually though, it will die in the air and deadstick. Is this just a tuning issue that I need to work on more or perhaps would moving the remote needle to the carb help the low end tuning?

Appreciate any advice. Thanks!

Welcome to the wonderful world of Evolution engine limiters!

This is the "walking needles" problem I've often referred to in other posts.

What you need to do is the following.

- Loosen the "grub" screw on the blue limiter collar fully, then pull the collar straight up and off the needles.

- Pull off the "clips" ( which look like inverted pen pocket retainers ), and bend the clip itself towards the circular retainer, to apply more tension.

- Remove both needles completely.

- Clean the needles of ALL fuel. Get them dry.

- Clean the receptacles for the needles of all fuel, get them dry and clean as well. Make sure you leave NO debris or lint inside.

- Using a microdrop applicator, place an ever so TINY amount of thread locker blue on the threads of the needles and turn them in to the defaults.

- Put the clips back on, now hopefully much tighter...

- Start your plane, tune it up, perform a nose up and down test to check your settings. Get it tuned perfectly on the ground.

- Now if you wish, re-insert the blue collars, with the pin at the center of the adjustment arc.

This will set a new adjustment limiter range for quicky tuneups.

The clips and the thread lock will prevent the needles from walking.

You can also place a bit of cut up exhaust deflector tubing over the needles to press the clips against the detents.

I've used the latter at the field as a quick on site repair to the "walking needle" problem...

Your first sentence had it right, Opjose, except leave out the word "limiters".

I had my fill of those engines, up to and including the 100NX.

CGr.

Yeah, don't get me started on the 1.00NX! Piece of #@$(%!

However I have had good luck with the PTS and the .60 engines after doing the above.

I knew I wouldn't be the only one with this problem. Thanks for the help, I'll give it a shot.

One note on those limiters and grub screws.

The first time I tried to remove the blue collar I had a hell of a time.

The ( idiot ) at the factory had screwed in the grub screw so much that it deformed the metal of the needle valve.

So even with the grub screw fully off the raised metal was preventing the collar from coming off.

I had to use a gear puller to remove it.... but it was a PITA to start, because the collar sits so close to the bottom of the needle valve.

I wish they left these things off, maybe supplying them in the box, and advising the novices to let an experienced engine tuner, first set their engines, and then install the limiter for the novice, to get things right.

I have to say that my first was their .45 trainer engine (well, that size is what they implied but never really stated the size). Anyway, I flew the be-jeez out of that engine. Then I bought the 100NX AND a .60. The 100NX gave me so much trouble that I got very discouraged with them and brought them to the LHS and put them on consignment.

To bad too.. when they ran ok, they ran great. It was trying to get it to run at all, or more than 2 minutes, was the problem.

CGr.