Hi I just picked up my first gas plane at auction today and couldnt find anything on the web about the engine. Its a US 40cc engine. I thought it was odd that the carb has no choke and if you spin the engine the the opposite direction and release it it springs back like an old .049 cox engine. Just trying to figure out what the oil mix prop size and rpm should be. THANKS

19x8

no choke is common on the older Quadra,US, and Zenoah type engines and it is equipped with a spring starter.

Ok I have been reading about something called a C&H (IIRC) Jump Start that you connect to the engine to help it start easier. Is that anything I actually need or do these engines start fine on their own.

Sounds like you have a US41 engine with a spring starter. It will start fine if you set the prop. with the tip of the blade that you plan to hold as you wind it back to about 7pm. to release. I wind it back, starting with the tip at 1100am. and go back to 7 pm. on a clock face. You want the magnet to be 180 degrees away from the senser. Be careful to get a good grip on the prop. because if it slips from your hand you will have a cut. I use a welders glove on that hand. hope I hav,nt confused you to much. Also you want to choke it until it is wet and I found that a 18x10 prop. works best on that engine. Wayne

Thanks. Your description of setting the prop made perfect sense. Im guessing you are saying to have the magnet at 180 degrees from the sensor when the prop is wound to 7 o'clock. I found an old posting saying that the oil mix should be 32:1 does that sound right?

I agree.

I have found that am 18X10 works well, too. I use a 32:1 gas/oil mix.

We all forgot to say that the US41 engine is a low RPM engine , about 7200. It has good tork and that is why I used a 18x10 pitch prop. At four&one half lbs. it is best to put on a short nose plane with good wing span. I flew it on a Stinger 120 plane with a wingspan of 80".Wayne M.

Thanks for your help. The guy I bought the plane from said it was a US 40 and that would explain why I couldn't find any info on it. Everything looks to be working on it. It has good spark and it has good compression. So all I need is a warm day. I think todays hi was 21 and wind chill was 13. Is there a cheap ignition kill for a magneto that would let me kill the engine from the controller?

They make one for a electronic ing. engine. I dont know of one for a magneto ign. You will need a kill switch mounted on the plane to kill the engine. You can find a toggle switch at Radio shack for a few dollars. It goes between the the two tips on the coil. When you flip the switch one way you ground out the spark and the other is open so the engine will run. I hope someone will jump and explain it better. Waynem

I understand the switch on the plane there is one already on it and it works. I just want to install something that is a fail safe to kill the engine if the throttle servo doesnt respond. Plus its pretty cool to land, taxi, and turn off the engine from the controller.

The only thing I can think of would be to rig a servo to a on&off switch and operate it with a spare channel. I have seen a way to make a switch push and pull at hobby shops. It would have to be a two way channel like the gear or mix switch. I dont think you will find a kill switch for a mag. ign. Waynem.