masonman

I have a tower hobbies .46.Was a great running motor till the past two days...It came on a tower 40 trainer an it bit the dust an i scooped up a 99$ nexstar ARK. The nexstar has been power by an O.S.70 4-stroke. Great engine plane combo...But it lands a little hot for my 14 year old daughter who is showing alot of wanto in this "ADDICTION". The 70 4-Sroke has found a home else where.........So that is why i am working with the .46

I run 15% cool power an it works great with all my glow stuff, except this(.46) one. I can start it an let it run a 1/4 throttle till it gets warm, then adjust the high speed as needed. Then i point the nose straight up an work the throttle an ajust till it has a good transition...Ready to stick it in the wind an go right...WRONG. I always clean it out before i taxi on the stripe by standing in front of the stab an working the trottle. If you hold the throttle at 3/4 or full it will pull real hard for 8 or 10 seconds then it dies like you turned off a key. It will do the same thing in the air if you go to 3/4 throttle or above, You have 8 or 10 seconds of hard runnin before you have a glider on your hands...Now if you never get above 1/2 throttle it will run all day. Sounds like it needs more fuel from the high speed needle? Its out(rich) 3-1/4 rounds. Less than that an it will not start to run decent. I have worked the needle out further than it is now, an it just starts spitting like its getting way to much fuel. So as for now i think the needle is about as close as i can get it. This one really has me wondering what has went wrong... I have the tower 61,an 75. They run like a 440 wedge an tune real easy.

Any thoughts an advise would be great

Desertlakesflying

My Feedback: (28)

had a os 46 fx that did that once and changed the needly valve body and the needle valve and no problems since. Couldn't tell you for sure though.

masonman

Took the needle asembly off my .61 an it was the same. I have put three glow plugs in it aswell(#8's)

meaden

To me it sounds like the low end needle valve is lean. I'd look for an air leak in the fuel lines or around carb too.

masonman

I will look into that airleak. I have tweaked the low speed an found the sweet spot on it. If the o-ring under the carb was bad would it make it act like this?

meaden

I had an engine that was running good and then got funky to tune. No real pattern to it. The carb wiggled loose from vibration and it was sucking air.

masonman

Yeah, you have my noodle workin now. I think i'm fixxing to go see if that may be my prob

masonman

The carb pin is tight an the o ring looks good

Rcpilot

My Feedback: (78)

Put your thumb on top of the carb and your index finger under the case. Loosen the carb bolt. SQUEEZE the carb down tight and squash the O-ring. Tighten the carb bolt while you squeeze it down.

If it won't rev over 3/4 throttle without dying suddenly--it's lean.

Fatten the high speed needle 1 or 1.5 turns.

Start it and run it up to full throttle. It should be a bit rich. Lean to peak slowly and listen to it rev up. When you lean it 2 clicks and it don't rev no more--you just hit max RPM. Now back it down rich 1/4 turn.

High side is set now.

Set it down to idle and move your trim on the TX up to full trim for a high idle.

Stick a screwdriver in the carb to adjust the low speed needle.

Turn it in to lean.

Turn it out to richen.

Make adjustments slowly and wait 10 seconds for them to take effect.

If you turn it in to lean and it speeds up--keep going.

It will continue to speed up as you lean it.

Finally, it will slow down.

Back it up a bit (1/10th turn) untill it speeds back up and runs steady.

Double check the high side.

Go fly it.

masonman

I pushed it down when i tightened it. The needle is out 3-1/4 turns rich. Factory says only 1-1/4 to 1-1/2 to set. I'm thinking its way rich. If i turn it out anymore it wont hardly rev, an if it does it has to jump a lot of speed bumps first

Rcpilot

My Feedback: (78)

Thats a sure sign your low speed needle is cranked in too far.

Take the carb off.

Open the carb wide open.

Look up through the bottom of the barrel.

Do you see the end of the low speed needle in the spraybar? It should be about 1/2 way across the spraybar when the carb is wide open.

If your low speed needle is cranked in too far, you won't be able to see the end of it when the carb is wide open. It'll be closing up the hole in the spraybar because it's screwed in too far.

Do this:
Take the carb off.

Remove the low speed needle completely. Unscrew it and lay it on the bench.

Open the carb wide open.

Turn the high speed needle all the way in so it is bottomed out. Don't force it. Just turn it in until it stops.

Now back the high speed needle out 2 full turns.

Now run your low speed needle in about 4 turns and stop.

Now put a piece of fuel tubing on the carb nipple.

Stick a building T pin in the carb throat to stop it from closing all the way. Close the carb down so it is touching the T pin, but not smashing it. The T pin is just a guide to put the carb in the right spot for idle. The carb should be shut down all the way except for about 1/16".

Now blow through the fuel tubing. You should just barely be able to blow through it with pursed lips. It should just barely hiss ever so quietly when you try to blow through it.

Turn the low speed needle in and out untill you get just a hint of airflow through the carb when that T pin is blocking the throat open just a snutch.

Now--ya got the carb set about the right amount for an idle with that T pin in the throat.

Put the carb back on and set it real good on the O-ring.

Start it and immediately run it up to wide open.

Tune the high speed needle for max and then back it down 1/4 turn rich.

Now throttle back to a high idle and tune the low speed needle again.

If that don't fix it--ya got a bigger problem than I know how to fix without seeing it.

Safebet

My Feedback: (12)

You're sucking air somewhere.

masonman

Low speed was to lean an the cover than goes on the back of the crankcase was loose.......RUNS LIKE A CHAMP NOW. Thanks guys