My two flywheels appear the same. I dont think these homie engines use the flywheel as counter balance for the engine but I've been wrong before( its been a long time though,lol). Both my homies a very smooth as far as conversions go. Purpose built aircraft engine are generaly very smooth but I have no complaints about my homies or macs or ryobies. They all do idle a bit shakey when I over carb them a bit, but thats my doing, no fault of the engine. Piper