JS550 make funny sounds... Pre-ignition?

I have a loud pinging or vibration noise that is coming from the upper end or carb, not sure what it is, is that pre-ignition? Vibration of pistons? Any ideas? Listen carefully to the sounds changing. This is an 83 JS550. I rebuilt it after haven it given to me in parts. Pistons are +1 over size. I got new pistons, rings, pins and circ clips. This noise is not an all the time thing but it happens a lot. Also its not to clear in video but there sounds to be a rough sound coming from pump housing or the prop area, does that mean time for new bearings? I think it is making drag on the motor. I will post more videos of different sounds/angles.


Post Comment
Thank you! Your comment is awaiting moderation.