limbodancer

Need help wiith new OS 50 SX Ringed. I have been trying to break in this engine new from box. Seemed to run only on primed fuel for a few seconds and conked off. 2 turns on needle valve, full throttle and OS #8 plug. No adjustment done to slow idle screw from box. Fuel : 22% oil ( 50% Syn, 50% castor ) and 5% nitro. Running from bench with properly set up tank and plumbling. No blockade anywhere.

Cheers

Bax

My Feedback: (11)

If the engine's not drawing fuel, and the fuel system has no blockage, then you need to look at the needle and carb.

Open the throttle to full and look into the carburetor. You should see about a 3 mm gap between the needle and the nozzle. Many times, the idle needle's been set too lean, and that can block fuel flow.

limbodancer

Thanks, Bax. I didn't deduce that it might be the idle needle as I expected it to be set at factory. I have not tried starting it since but will take a look and have a go again. Do I need to open the needle valve to about 4 turns this time around ?

Bax

My Feedback: (11)

We'll open the high-speed needle 2-1/2 to 3 turns for initial running. That's plenty rich. The idle needle is set as above. Breakin is at full throttle.

limbodancer

Thanks, Bax. Got the engine running on song now. I opened the slow idle needle to 3mm as recommended and 3 turns on the needle valve. Will fine tune it now.