[rvanstory]

Recently had to replace a cylinder (#1) on my IO-540. Since engine was "balanced" during assembly by Aerosport Power, decided to replace the cylinder but NOT the piston (piston was fine) to maintain measured piston balance.

Upon 1st breakin flight of new cylinder, the engine did not seem as smooth as before. Can replacing a cylinder (but not piston) affect the balance? I just assumed that since the piston stayed the same, things would still be balanced, but now not sure. Any insights from others would be appreciated.

 

[Avanza]

Recently had to replace a cylinder (#1) on my IO-540. Since engine was "balanced" during assembly by Aerosport Power, decided to replace the cylinder but NOT the piston (piston was fine) to maintain measured piston balance.

Upon 1st breakin flight of new cylinder, the engine did not seem as smooth as before. Can replacing a cylinder (but not piston) affect the balance? I just assumed that since the piston stayed the same, things would still be balanced, but now not sure. Any insights from others would be appreciated.

I can't see that replacing a cylinder but not the piston would affect balance since
no moving parts where changed.
After run in of the new cylinder the engine will feel smother.

Good luck

 

[Freemasm]

Recently had to replace a cylinder (#1) on my IO-540. Since engine was "balanced" during assembly by Aerosport Power, decided to replace the cylinder but NOT the piston (piston was fine) to maintain measured piston balance.

Upon 1st breakin flight of new cylinder, the engine did not seem as smooth as before. Can replacing a cylinder (but not piston) affect the balance? I just assumed that since the piston stayed the same, things would still be balanced, but now not sure. Any insights from others would be appreciated.

Mechanically balanced? Flow balanced? Both?

Replaced with same Model and OEM?

Some OEMs claim (air)flow advantages over others. Based on that claim and the possibility that your jugs were flow balanced -> Yes. It is very conceivable that replacing a single jug could cause the symptoms you’re feeling.