Gas engine vibrations when idling
 

Hello,

Just started my new RCS SV 26cc engine and it vibrates like hell when idling. The engine was not started on the plane but on a wooden bench.
I'm not sure if the fuse and servos + electronics will stand so much vibrations.

It's first time am starting a gas engine and first time I'm planing to use a gas engine.

Do you have any advices ? Is it normal ? It can be solved by tuning the engine better ?

RE: Gas engine vibrations when idling
 

Tuning will do nothing for vibration.

Is the prop balanced?

RE: Gas engine vibrations when idling
 

Check and make sure all the mounting bolts are tight.

RE: Gas engine vibrations when idling
 

A rich engine will vibrate, especially if the low end is too rich.

RE: Gas engine vibrations when idling
 

Many gas engines recommend breaking them in on the airplane rather than a bench because of the additional vibration. Gas engines by their nature will produce more vibration because the gasoline burns faster in the cylinder. It is therefore more critical to properly balance the prop as well as make sure your electronics are properly vibration mounted. Recievers and batteries wrapped in foam, servos not mounted so tight the grommets are crushed, etc. Engine mounts for gas engines are also designed to use the airframe to absorb vibrations. Bench mounting may overstress the engine mounts and lead to premature failure.

Brad

RE: Gas engine vibrations when idling
 

You definitely might not want to run it on the bench. Often, the instructions for gas engines will advise against bench running because there is nothing to absorb vibration and the mounting points on the engine could possibly fail. When mounted on the airplane, it absorbs this vibration.

If it is really sloppy, rich, it might vibrate less when tuned properly but it will still have some vibration. There is no way around it. You have a fairly large, single cylinder engine so it is going to shake.

Just make sure your firewall is secure, wrap critical stuff like receivers and batteries in foam and use thread locker on all bolts and screws. I like to check all of my screws when I take a plane to the field as well. It will work just fine.