G'day Algis,
Sounds a little strange to me. The metallic sound could be that you have your chain too tight, it needs to have about 50mm slack at least, when it's on the side stand or up on the centre stand.
Or, you could load up you and your partner and get someone to check that there is still about 10cm slack at least.
This could also be part of the power loss, but not that likely. The power loss could be any number of things, including bad fuel, old plugs, poor ECU mapping or some other after market add on that's causing a problem.
Need more info on that.
Mick