engine problem?
 

I have moved up from flying electric to gas. I now have an avistar. I really love the plane. I have one problem. when I pratice landing, I turn the plane around and go back to the end of the runway.When I throttle back up for takeoff, the engine seems to lose power. I have to do a runup for about 30 seconds before I can takeoff again. I have the stock la40 engine. I runs fine when in the air. Is the tuning not right or do I have another problem

RE: engine problem?
 

probably just a little rich on the low speed adjustment. Nothing serious. just a tiny tweak should help it.

RE: engine problem?
 

If it real cold it'll run a little funny that way...I have an avistar also with the la40 in warm weather it runs like a champ but in cold weather she'll fire run fine on idle or high throttle...but going from idle to full quickly seems to bog down then start to react.

RE: engine problem?
 

As it gets colder, you have to adjust the mix just a tad.

RE: engine problem?
 

Sounds like your low speed needle it a little rich which is causing the engine to bog down a bit until it burns off some of the extra fuel when transitioning to the high end. When you adjust your low end needle only adjust it about 1/8 turn at a time. You don't want make quarter or half turn changes like you might on the high end needle - this would be too much and throw things off worse than they are now.

If you are flying in the cold you do need to run a little richer than normal since the cold affects the timing of two stroke engines.

RE: engine problem?
 

The hottest plug you can get will help in the cold temperatures too. Was out flying yesterday at 3 below F. Higher nitro helps too. I run 25 %.

RE: engine problem?
 

thanks for the info. that air bleed needle is real sensitive. I have to remember, out is lean,in is rich

RE: engine problem?
 

umm look, he's in Florida:eek: no 3 deg. there!!

RE: engine problem?
 

First, how can you stand to fly in -3? [X(]Second, How do you keep this engine from going "boom" with the 25%?Do you need head shims? If i did that, I would have a face full of engine( I would be out in the field "look, I found the piece of crankcase that says OS on it!":eek:

RE: engine problem?
 

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RE: engine problem?
 

Since I have run up to 60% nitro in custom mix fuel... the 25% is obviously not out of line. (at that level of nitro... the methanol is a coolant, not the primary fuel) don't go lean with super-high nitro... you melt pistons.

You can get 30% nitro fuel off the shelf...

As for flying in the cold... If you can stand it... the airplane really doesn't care. You have to limit the cooling of the engine with baffles... and might need an on-board glow system to keep it running. (really cold air can put out the glow)

I've flown in rain, snow (while falling) sleet and freezing rain. (had to land due to icing on the wings once...)

RE: engine problem?
 

WE have the same problem here. At times, if you don't fly in the elements, you don't fly. I used to fly no matter how cold it got, well to a point. I usually run 30 to 40% in my smaller engines. 25% runs good in the bigger ones, but if you lean them, they blow plugs fast. I run as high as 60% in the tiny engines if I can get it. Thats harder to come by. Haven't used it in years.