Rattling sound after startup-

[RKS_DK]

So after winter break I started up my T3 (94 1100 cali engine 30.000km) and went for a drive, when it was warm I had it pull some, but everytime I gave it throttle a "rattling" kinda sound appeared, like nuts and bolts were loose in the rocker cover... after a visit to the gas station it was gone however  ??? it runs very well overall, but abit concerned over that sound from get go, the engine is low milage, drove about 6k(km) last year with no issues at all. Had oil+filter changed this winter as only service.
Last winter I had everything checked by a guzzi mechanic, and had carbs+ valves adjusted.

Had the exhaust removed for repainting also.

Any thoughts ?

[RKS_DK]

Startup today-

http://youtu.be/DKMwEMUu6wY

[RKS_DK]

Well the weird thing is that its gone now, its also not present in the video btw.

Chain tensioner was replaced 2 years ago.

[Chuck in Indiana]

Maybe it had a bad batch of fuel?

[lrutt]

sounds like low octane or separation after sitting. If you hear that back off the throttle immediately. You do not want to hear that noise, bad juju for the motor.

[creaky99]

If you are using E10, it is possible that the fuel degraded thus lowering the octane of the fuel resulting in detonation under load. Alcohol blended gas has a shelf life of only 90 or so days. The fact that with fresh gas the problem disappeared indicates that might have been the problem. When I park my bikes for the winter, I fill the tanks with no alcohol gas and add some Stabil. They start right up even after sitting 2-3 months.

[RKS_DK]

Thanks for the input, the fuel makes sense, and was nearly empty when I put it away, had a knee surgery just before season ended, so dident get to prep it much for winter this time  :(