dz160 stop in Loud noise
 

Hello

my engine dz160
Event that happened to me today
I tried to find the peak position ( max rpm ) by adjusting the HS needle valve
i close the needle more and more And suddenly the engine stop in Loud noise and the prop nut Released.
this happened when the HS needle approximately 0.5 turns open from fully closed.
1. Why did it happen and if I caused damage to the engine ? ( Then I could run the engine again )
2. How do you recommend me to find the max rpm ?

Thanks
kobi

RE: dz160 stop in Loud noise
 

Sounds like you ran it lean enough for it to have preignition. You may have damaged something but there is no way to know for sure without a tear down. 1/2 turn out is pretty lean. Were the RPM increasing the whole time?

RE: dz160 stop in Loud noise
 

As Petec states, you may have done damage, bent valves are the most common, you may have put half moon circles on top of the piston as well.
The circles on top of the piston are ok, but check the valve stems for straightness. But also be aware that piston damage etc is also possable,
strip it down and inspect.

I don't know what Petec and others do in the US, but I prefere the pinch method of determining the max rpm of the 160, there should be a previous thread somewhere
about this method.

YS Servive Down Under

RE: dz160 stop in Loud noise
 

I agree. it sounds like detonation.  Could you hear it "cracking" before you got it so lean?  That is detonation or preignition.

RE: dz160 stop in Loud noise
 

Thank you for answers

If it's very disappointing because of a momentary mistake like lean the engine
Can be caused damage to the engine,
What, who designed the engine did not think that an error can happen ?

RE: dz160 stop in Loud noise
 

A lean run can damage any glow engine

RE: dz160 stop in Loud noise
 

A lean run can ruin any engine, as can over-revving.