What’s causing this loud noise?

[Keoki71]

I finally got my kymco agility 50cc running and installed a 80cc bore kit whole new top end, it has somewhat a hard time starting, but it ran a good 3-4 mins and starts to bog out while in idle, and making this loud noise , idk we’re it’s coming from. I posted a video, hope my kymco family help me out thanks a bunch!


https://youtube.com/shorts/S9Nnxm3ruWM?feature=share

[CROSSBOLT]

I finally got my kymco agility 50cc running and installed a 80cc bore kit whole new top end, it has somewhat a hard time starting, but it ran a good 3-4 mins and starts to bog out while in idle, and making this loud noise , idk we’re it’s coming from. I posted a video, hope my kymco family help me out thanks a bunch!


https://youtube.com/shorts/S9Nnxm3ruWM?feature=share

Did you check or set the piston ring end gap BEFORE you put the cylinder on the engine?

[Keoki71]

Did you check or set the piston ring end gap BEFORE you put the cylinder on the engine?

I did, but it might had moved while I was putting the piston in the cylinder. Might go check on that and I’ll let u know

[CROSSBOLT]

I did, but it might had moved while I was putting the piston in the cylinder. Might go check on that and I’ll let u know

Your reply indicates either you have no idea what piston ring end gap is or I am not understanding what you said.

End gap is the GAP or open space of the piston ring when in the cylinder. It can be made larger (if required) by grinding off the end(s). It is checked by putting the ring into the cyclinder by itself an measuring with a feeler gage.

The biggest mistake is people (including me) assuming this gap is set in every new piston ring.

[de dee]

check the driven pulley for grease, Ive heard that noise too,  totaly dry  and sounds like it is from the variator my new one is ordered,.