1965 A10

The moter was rebuilt by a local shop that has a good reputation. There is a thumping sound when it idles possibly on the left side but not certain. I removed the primary cover to check the chain adjustment but all looks well. Tomorrow I will start it up with the cover off and see if I can spot anything. Any ideas? There is no movement in the crank side to side.

1965 is a bit late for an A10. Post a picture of the bike.

What’s important is up-and-down play on the timing side end of the crank.

If it is an A10, is the crankshaft cush drive in good order and tight? Can the outer cam be rotated any on the splines?

I meant A65 unit construction. Have not inspected the timing side yet