all the engines are allright, everything mecanical ever built has a weackness or problem tbh
i personaly dislike cam chains alltogether only reason there on engines now is because people b!tched so much about haveing to change belts, but chains can bite you in the arse just as redaly as a belt and they bite much harder. usally down to lax serviceing.
ie driveing 4 miles a day, thats horrible for engines really you shoud change the oil much more often with that sort of use but no one ever dose