Rattle in rear cylinder when cold and idling down trhough 1600RPM

[NewfieVaradero]

Hi All, this issue is driving me nuts, on cold start I get a momentary rattle after running for around 15 seconds, it happens when idle passes down through 1600RPM and only lasts 5-10 seconds before going away. I'd swear its Cam chain rattle from the sounds of it but she has new tensioners and everything measures perfectly. Bike has 10000 Kms on her and she's a 2008. I have the valve cover off and all valves are measuring within tolerance, actually a little on the looser end of in Spec which is how I assume she was down from the factory. Do I pull the head and try to figure it out or button her up and ride and learn to live with the noise? Once warmed up she's quiet as a mouse and won't make the noise again until a cold start.

[S Barker]

I think it depends on what you use the bike for ?

If the bike is an essential mode of transport you probably need to get to investigate further, if not then keep an eye on it and see if it gets worse !

If it only lasts for a few seconds just after the bike has been started it doesn't sound that serious.

[John J]

Is the engine oil level right and the correct grade of oil used? I'm thinking it may be starved of oil for a few seconds or it's taking longer than normal for the oil pressure to come up