Hi Guys,
I need help! I`v been flying my dirtybridie all season with no problems. The last two flights I had to dead stick the plane in because the os 61 keeps quitting in mid flight. I pulled the tank out and the and I could`nt find anything unusual. The motor runs real strong and idles fine on the ground. Any suggestions would be great.

thanks,
Frank

As long as there are NO air bubbles present in the line and the fuel is FRESH ... then I would suggest a simple tweaking or going over the carb adjustments again like you would at initial break-in on your engine. Could be that with this extreme hot weather we have been having, that the engine needs a little leaning or richening up a couple of clicks one way or the other ?
Might even be time to replace your glow plug ?
I know I've had to tweak both of my engines over the last 2 months, one had to go a tad bit lean and the other rich by a click or 2.
I live in a high altitude with a high humidity rate too so this may not be your case, but it cured my problem on my Sig Four Stars.

2 strokes,
I did try replacing the glow, and when I flew last it was only 80 degrees F. At times I do see bubbles in the full line. What does this mean , and how can I fix it?
thanks,
Frank

If you cannot get 2strokes' advice to work for you, go back and look at the tank carefully. First look for air bubbles when the engine is running at cruise power.

Then examine the tank very closely expecial for the action of the clunk. Does it move to all corners of the tank and look that it is not folded back on itself.

Enjoy,

Jim

Like Jim said, check that the clunk is doing it's thing in a normal fashion (not folding back on itself) and restricting fuel.
Bubbles USUALLY occur when there is a air leak ANYWHERE between the fuel line connections from your tank to the carb. Afterall, if an engine is pulling air and the fuel tank is 1/3 rd. filled or over, it has to be coming from somewhere.
Things to check:
Hardened or loose fuel lines close to every connection.
Clunk inside tank folding back and restricting fuel as Jim suggested.
See if the needle valve will shut off the air completely by blowing thru the fuel line while the valve is in the closed position, if not, it could be a bad O ring on the needle.
Don't know what kind of engine you're running either, some are known for serious carburetor and needle valve leaks like my Tower .46 but I have mine under control. New carb. O ring and needle seat cured it.
Also ... I noticed some folks at our flying field over the weekend pumping the unused fuel inside there planes tank back in to there fuel jug .... That is a BIG NO NO ... it will seriously contaminate the fuel and can cause it to foam way more than normal. The fuel will also lose it's punch (degrade it).
I would try going thru the tweaking stage first, a couple of clicks rich or lean might cure it.
Good Luck
Mike

To help prevent bubbles , there is a clunk made with a screen on it so as fuel is being sucked into the needle valve hose the bubbles break. I believe tower hobbies have them for sell.

I had an OS do that to me as well. First flight...was running fine (as usual)
then just quit for no reason after a couple minutes into the flight. It restarted
no problem....I reset the HS needle....again, running fine....then just quits
again. This time I put in a new plug....reset the HS again. This time, running
fine quits again....but this time the engine has no compression.

Not good....the engine chunked one of those nickle plated cylinder liners. []

FBD.