Engine noise at idle

[Harryotransport]

Engine when got it running sounds rattly at idle then when rev it .sounds nice then about 5 - 6000 exhaust does a bit of banging like a backfired.any suggestions

[autonoob]

Have you tried to check the oil level of the bike?

[DenverWinger]

If the carburetors are out-of-sync on the 4 cylinder wings they'll rattle like a bucket of bolts at idle. It's just whatever slack in the primary chain slapping around inside the engine. Doesn't hurt anything, but doesn't sound very good.

Backfiring at revs sounds like a lean carburetor. Maybe a slide is sticking. Or there's numerous other causes for running lean. Sounds like bike needs some carb service. Could try a few tanks of fuel with double-dose of Seafoam or whatever equivalent found in the UK to see if that helps, first.