I JUST PURCHASED MY FATHERS HANGAR 9 ALPHA 40 TRAINER OFF HIM IT ONLY FE LIKE 6 TIMES LAST YEAR. WE WERE TRYING TO FINE TUNE THE MOTOR THIS AFTERNOON. AND WE COULD NOT GET IT SET RIGHT AT ALL. WE THEN NOTICED AIR BUBBLES COMMING FROM THE HIGH SPEED NEEDLE VALVE WHICH IS LOCATED AT THE BACK OF THE MOTOR CARRYING FORWARD INTO THE CARB CAUSING IT TO RUN IRRADICALLY AT FULL THROTTLE AND RUN VERY LEAN. WECHANGED ALL THE FUEL TUBING, AND OPUT SOME FUEL TUBING AROUND THE NEDLE THNKING MAYBE IT WAS SUCKING AIR. WE JUST GOT BACK FROM RUNNING IT AGAIN AND NOW THERE ARE AQ TONE IF LITTLE AIR BUBBLES COMMING RIGHT FROM THE FULE TANK LINE TO THE HIGH SPEED NEEDLE. WE KNOW THERE MUST BE A PROBLEM SOMEWHERE IN THE FUEL TANK BUT IT IS NOT LEAKING AT ALL AND NONE OF THE LINES APPEAR TO BE TANGLED OR ANYTHING. IF ANYONE OUT THERE IN RC LAND COULD GIVE ME SOME INSIGHT AS TO WHAT COULD BE WRONG IN THE TANK TO CAUSE SO MANY BUBBLES IN THE FUEL LINE THAT WOULD BE GREAT!...ALSO FOR REFERENCE THE MOTOR IS THE EVOLUTION .45 POWER TRAINER SYSTEM. THANKS IN ADVANCE TO ALL WHO MAY TRY TI HELP IN REGARDS TO MY PROBLEM!

Hi,

sorry your having problems. Did you change the fuel lines from and in the fuel tank? If you did not the bubbles from the needle to carb. could have been coming from the tank in the first place.

I generaly check out a tank under water, put it under water and blow air into one of the lines and look for air bubbles. I put a new piece of line on to blow on.

Oh by the way, go to low caps for the posts , its easyer to read.
sticks

thank you very much for the input stick 40. i will be sure to try all that out and pray everything works for the best. good luck flying!

Is the fuel tank padded. If you are getting to much vibration you will get air bubbles also. Shouldhavefoam rubber around the tank.
Rich

You might also check out the brass tubing.

just for reference, the alpha 40 does not come with any foam rubber around the tank.  I have one, and tank is not padded, but I have never had any problems yet.

The plumbing inside the tank may be your problem. Open the tank and make sure that the clunk and line between the clunk and output feed to the carb is good.

thanks guys for all the info, we changed all lines and plumbing inside the tank and put a new stopper in. so will be fireing it up today and hope it has solved the issue. as for the foam rubber around the tank. its something that i would like to do, but the heck if ther is any room to get any rubber around that tank. it is such a tight fit we werent able to get any around it and still get the tank in. but it never came with any so hopefully things will be alright.

I just went back and reread my post. I close off the other end of the tank while its under water and blow in the clean one.

Some or all the newer fuels have anti foam agents in them. I have had a couple of arf's that can't be foamed around the tank and they seem to run ok.

Make sure you have the lines on the right way also, we have done that a few times its easy to do.

sticks

Really no need for foam around tank. I know some may disagree but been doing this RC thing for over 55 years and only ever use foam padding if tank is not held in place without it. Proper plumbing is main thing.

Just a thought one of the guys in our club turned up the other day with a similar problem ,on pulling the tank to bits he found that the brass was all eaten away the other guys reckon nitro eats brass it was totally eaton away and had only been sitting for 3 months with maybe a teaspoon of fuel in tank ,,maybe worth looking at (just another option to check out )

yeah i pulled the tank all apart and re plumbed everything with fresh stuff took the needle valve off blew thru it under water and no leaks there. put the motor all back together on the plane. and i am still having trouble getting it to run consistantly. it will berunning just fine then all of a sudden, bam! it start leaning itself out a lot and just screaming. there are no big air bubbles that i can see comming through the line just some very very almost micro sized ones. i dont know if its just a quark with that evolution trainer system or what. but im almost affriad to fly it becasue i dont want it to lean out and burn up on me in the air..m,y dad says im being to anal about how the motor runs and im trying to have everything be to perfect, and that 2 strokes are finiky. maybe hes right i dont know. i wasnt the one that owned the plane from new so i dont really know how it ran in the first place.