Hi there hope anyone can help

I am having a lot of trouble with my OS Max 40 engine that I have installed in a SPAD plane. The engine has the following problems as I can see them;
1. The engine doesn't like throttle transition, andis 'jerky' and takes on final approach
2. After much less than half a tank, the engine starts to quit.

Any ideas about these symptoms? Any help much appreciated!
Regards
Gareth

How is your tank's height relative to the position of your needle valve

Yeah, OS engines are allergic to plastic planes. Treat the symptoms with balsa.

Seriously, it sounds like you're not getting pressure from the muffler to the tank, and you've adjusted the idle to compensatem but as your tank empties the mixture gets leaner and kills the engine. Check the tank stopper, muffler, and pressure line for leaks and blockages. If you have a fuel filter fitted check that it's clean. When you're sure the pressure's getting where it needs to be, re-set your idle mixture.

Gareth,


What type of OS Max .40 engine is it? Tell us that, so we can better analyze what is wrong...

There are certain 'musts' that apply to all engines...

The fuel-tank must fully isolated from the air-frame with 1/4-1/2" latex foam and be installed as close as possible to the engine.
This prevents the clunk from being deflected into the air above the fuel and ingesting air, by engine vibrations... as well as making the fuel-draw effort minimal, with the plane's nose up.

The tank center-line must be at the same level as the middle of the carburettor's barrel - this make the engine behave the same in upright and inverted attitudes.


If the engine is new, how did you do the break-in? If it is a non-ring engine, [link=http://www.rcuniverse.com/forum/Tapered%2DBore_Engine_Break%2Din_%2D_Upgraded/m_1850473/tm.htm]this[/link] is the best way; better than what the manual says.

What propeller are you using?


We'll carry on as you add more info...