I have a OS .46 that is well broken in and it is installed in a Sig Kadet LT40.

I have started having problem with the idle mixture screw backing out. The engine starts to get tempermental in starting and the transition from idle to full power is spitting and sputtering.

This happens after four or five flights.

Readjusting the idle mixture makes everyting fine again.....any ideas on how to keep the screw from backing out by it's self?

The engine is not vibrating I balanced the prop mounts are tight, etc.

Appreciate any help thanks.

To help, please let us know which engine and which carburetor you have. That makes a LOT of difference in how we can reply.

Thanks for the reply.

I have a OS .46 FX with the 40 B carburetor. Engine is approx two years old and according to my log has 92 hours on it.

Still turns 12.5K with 11x6Master Craft prop. The idle RPM is approx 2650.

Appreciate your help.

Flyer,

With that much running on the engine, it's bound to have had some wear due to vibration. It sounds like you need to disassemble the carb and replace the o-rings on the idle mixture adjustment. Here's the stock number and suggested retail price:

OSMG7392 22781800 O-RING S #2K/2SB $2.29

You can order the part through any hobby retailer who sells O.S. Max engines and accessories.

Thanks for your help, can you tell me where I can find a illustrated breakdown for the carb? makes it easy to get all the parts back in the right place.

Thanks again for help.

Hirc,

The exploded diagram for the carb is at:

http://www.osengines.com/parts/exploded-views.html

Found it Thanks

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