Help! YS-120AC Cannot shut it down?

[Snoopy1]

Have a few of these but never this problem it is YS 120AC. Runs great puts out all the power no hesitation, run perfect except cannot shut the motor down after a flight. I believe it has an air leak some were but cannot find it. Stripped it down check everything cannot find a thing wrong. Replace all the silicone tubing. Have ordered a gasket set and an O ring set from YS-engines USA. But do not believe it will solve the problem. Even when I put my finger over the intake it is bearable able to keep running but it does for about 20 seconds, and then dies.
Does anyone have any suggestions.

 

[Alky6]

Have a few of these but never this problem it is YS 120AC. Runs great puts out all the power no hesitation, run perfect except cannot shut the motor down after a flight. I believe it has an air leak some were but cannot find it. Stripped it down check everything cannot find a thing wrong. Replace all the silicone tubing. Have ordered a gasket set and an O ring set from YS-engines USA. But do not believe it will solve the problem. Even when I put my finger over the intake it is bearable able to keep running but it does for about 20 seconds, and then dies.
Does anyone have any suggestions.

A bandaid and doesn't solve the issue causing the problem, but will allow you to shut the engine off.... how about a loop of wire that pulls and pinches the fuel line closed?

 

[Snoopy1]

A bandaid and doesn't solve the issue causing the problem, but will allow you to shut the engine off.... how about a loop of wire that pulls and pinches the fuel line closed?

As crazy as it may sound if I cannot solve this problem it is a solution

 

[Snoopy1]

Now that I am thinking about it again and the suggestion from @Alky6 did the pylon boys not have a fancy way of shutting down there engines because the if I am not mistaken they did not have a throttle on their engines.

 

[Alky6]

Now that I am thinking about it again and the suggestion from

Not sure. But I have seen many a pattern plane with glow engine that has the looped wire around the fuel line that was servo operated to pinch the fuel line to shut down the engine. @49dimes or @dhal22 may have some pics or drawings of this simple mechanism.

 

[dhal22]

Pinch it against the firewall. Servo in the fuse, wire through the firewall, around the fuel line and draw the wire back enough to pinch the line. Adjust your servo travel in your radio.

 

[Snoopy1]

Thanks for all the suggestions.