Problem two is just from running a little lean I think, so that'll be sorted by jetting correctly.

Problem two will be corrected by fitting the piston pin circlip the right way and installing the rings correctly, together with a little relieving as Stephen says.

I have use Langcourts twice, and had varied results. Firat time wa perfect, second time I had to return the barrel for replating and cleaning up. I won't use them again!

Once you're certain those bits come from outside the engine, get it back together with new parts, and sort the jetting.
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