This engine does have the plastic oilers for the cams. I would say it is either pieces of the chain guides or the oilers, most likely the guides. I would not start the engine again until you pull the covers off and inspect them. You might have dodged an expensive bullet by finding the pieces before one of them broke and the chain jumped.

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I really gets fun when they all don't run

84 500SL
99 Jeep XJ
93 Jeep YJ
03 Custom Softail