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teedee .049 question

I have a teedee .049 that has only been run on the bench. I cannot get the engine to run smoothly. It will run for a bit, and then lean out and surge, and then smooth out. It's defintely not stable enough to actually trying to fly something with it. It acts as if the fuel supply has something intermittently blocking it. It's not my bench setup or fuel tank/lines. I have a teedee .051 that runs smooth on the same bench, and tonight I fired up an old black widow .049 on the same bench, and it hummed as smoothly as can be.

I took the brass needle valve assembly apart and cleaned it, I don't believe there is a problem there. I'm not sure what else could cause this. Do these engines have an exceptionally long breakin period? Should I run it on some oil rich fuel for an hour? Does anyone have experience with this specific engine and can comment on what is likely to cause this? If this were a reed valve engine, I'd suspect the reed valve.

Reply to
Ook
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If you get desperate for an answer, try swapping the .051 cylinder and piston onto the .049, and see whether the problem follows the case or the cylinder.

If it's really leaning out I'd look for fuel system leaks. If the needle isn't sealing in the spray bar you could be pulling a bit of air in past the threads. I assume you're using the same fuel tubing on the .049 as the .051, or I'd tell you to suspect pinholes and replace the tube.

Bey> I have a teedee .049 that has only been run on the bench. I cannot get the

Reply to
Tim Wescott

I think that is what I'm going to have to do next - start swapping parts back and forth and see which piece the problem follows. I might strip it and clean it first - although it's only been bench run, it sat in storage for many years.

Reply to
Ook

Good idea, but don't swap the cylinder right away. Try swapping the heads first.

Ook wrote:

Reply to
Robert Reynolds

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