hi people,

I have a hobbico avistar select with 40 LA. I've almost done 10-15 flights. My 40LA engine is giving me problems these days, it keeps on shutting off either inflight or when running at full speed on the runway. Please help... I've checked the fuel tank and the tubes for any leak but found nothing. The engine runs fine whenever I set the needle valve setting to optimal position, but it slows down after a minute or 2.

Please help!

I'd say you are lean, causing the engine to overheat. This is not a good thing. give it a 1/2 turn to the rich side and see what you get.

Sounds to me like it's going lean on you. Have some one hold the plane vertical and adjust for a good run at high throttle in that position. This will give you a slightly rich setting when level. If all is well with the tank pick up and the lines, and nothing has come loose on the engine (all this should be checked as you have) it should run fine.

I agree with the first two people. You may want to try a new glow plug too.

I think my needle valve setting is right as well.. I've flown with that setting for the last 15 flights but now it is suddenly troubling me.

I would still double check it!!

The LA 40 has what I think is called an air bleed carb. What I mean is there is no low end adjusting screw, just a small air hole. My first trainer had this on it & the hole had a little trash in it causing the same problem. I cleaned everything out good & the problem went away. May not be your fix but its worth a shot. I know how frustrating that can be.

...also check the backplate bolts--if they are loose it can cause a leak and create the situation you are experiencing.

Also keep in mind that you're going through break in. I assume it is new. Things are going to change a little. You don't want to adjust for maximum rpm on the ground because in flight, it will lean out a little on you. Adjust to maximum and then back off 300 rpm's or so. Things like humidity and temperature will affect your settings as well.

3D Champ;

Did you pull the fuel tank out and look at the lines. It sounds like the clunk is forward and stuck on the top of the tank. Before you pull the tank try a new glow plug. That would be the first thing to do. I'm leaning towards the lines in the tank. Also could be a cut line in the tank near the brass tubing.

Regardless of how it ran for the last 15 flights the high end should be dialed in whenever you go to the field. Weather changes and so does the settings. You can fly all night on a certian setting, but did you ever notice (here in the northeast any way) that as the sun starts to go down, the drop in temp is just enough to make the dew drop, along with barometric pressures and the engine that ran fine all evening, is now too lean. Also as some one else mentioned, you will notice differences as it breaks in. Joe

yeah i was having the same problems with my ZEN but i changed my glow plug now its ok.

I have the Avistar Select and after a few flights I noticed some small white residue in the fuel line, around the intake to the remote needle. It looked like shavings from the fuel tank.

A little compressed air in the line and it went away. Ran fine after that.

With the airbleed lowend screw, it's right to richen and left to lean, which is opposite of the needle valve.

Lately I've picked up on that as well. Looks like the plastic the jug is made of. Now I have a filtered pick up clunk for inside the jug and a filter on the feed line. Joe

A guy at the field was having the same problem. Turns out he had his vent line hooked up the carb and vice versa. The plane would run great for a few minutes and then die. Just something to check.

He's right... I adjust mine prior to every flight actually