Chip in piston near piston ring - ok to reuse cylinder

[Toddler78]

Hi Guys,

Bit of a left field type of question, I bought a cheapo chinese 2 stroke scooter just for some cheap thrills and a zippy cheap run about. When I bought it, it wasnt running. I got it running but not consitently. It has just had a 70cc big bore kit installed and I dont know how many kms it had done before issues.
Anyway fast forward, I did a compression test on it and was getting 50% of what I should be getting, pour a little bit of oil into the combustion chamber and up goes the compression. This said to me the piston,rings and/or barrel are stuffed.
I tore the engine down. visually the barrel looks ok with no big scores, however I found the piston to have the slightest of chips out the side of it where the piston ring seats, matching this up with the barrel suggests to me the ring wasnt properly seated and has caught on the exhaust port. A rough edge on the exhaust port seems to comfirm this.

What I want to know is do you think the barrel is savagable, and I will just require a new piston or, bite the bullet and replace the whole lot?

A top end kit for these things arent overly expensive but if I can get away with just a piston then Id be happier as this was just meant to be a budget bike.

Cheers

[Toddler78]

Here's a photo of the piston and the barrel from the top43154314

[Smitty]

.. piston is def fooked
and looking at that barrel.. if its alloy it should go in the bin
if its cast then you might .. just might get away with a hone

if it was me.. but depending on the $ I would bin both and get newies
as you want reliability (no use pushing the fooker)

[mjrandom]

Like Smitty said if you can then replace both but as a kid I had a go kart engine that looked worse than that. I honed the bore with a home made home from a piece of dowel and sand paper and filed the chunky bits off the piston and gave that a sand too. New rings and it never missed a stroke.

[IJ.]

Can't see how that happened, 2 stroke pistons usually have a pin in the groove to stop the rings dropping into a port, might have been assembly error though..

If a barrel and piston aren't too exe I'd replace both and be done with it, like Smitty I don't like to push ;)

[Bling Bling]

I cant believe this happened with the build quality of a chinese product maybe a warranty job NOT.

[Toddler78]

Cheers for he response guys. The funny thing is that the kit is a mallosi kit which is an Italian kit. I the pic of the barrel doesn't do it justice, there are no deep groves in it, the line in the pic are just from the oil I put in there. I was thinking of cleaning it up with a hone and fitting an oversize piston, but I might bin the piston and keep the barrel as a spare and buy a new kit.
The piston ring gap was huge on these so it wouldn't surprise me if the rings have rotated over the dowel and snapped, chipping the piston, or something was dropped in the engine during rebuild and it busted the piston exiting the exhaust port