nc30 making an intermitent clattering sound ?

[Dynamohum]

been working my way through some of the issues on a track bike i bought. ive sorted out the carbs and cooling system so far and had it up running ok . its now developed what i can best describe as a light clattering sound i have yet to check valve clearances but the sound appears to be coming from lower down the engine somewhere .

its running on all 4 , no smoke starts idles . the noise appears at idle then stops when you rev the bike then returns as the revs drop down then disapears at idle then re-appears again its not like the knocking you get with out of balance carbs at idle, can only describe it as sounding like somewhere between noisy valve gear and something more serious

i have drained the oil and all seems ok on that front could it be the clutch basket any suggestions welcome

[skinnydog0_0]

can you feel any vibration through the engine/sump when you hear this noise?
If you can try to pinpoint where it feels worse might help narrow down where the noise is coming from.

[royster81]

Sump off and look for chucks/bits of metal. Sam drained his oil and found nothing, took the sump off and found a bit of piston skirt.

[Dynamohum]

Sump off and look for chucks/bits of metal. Sam drained his oil and found nothing, took the sump off and found a bit of piston skirt.

yes that idea had crossed my mind royster the noise seems to eminate from the bottom end rather than the valvegear area . the puzzling bit is that the noise is not ever present seems to come and go depended on revs would a broken ring piston skirt etc show up like this in the same manner as small end bearings piston slap in a two stroke

work shifts are all over the place at mo so probably wont get round to checking till next week then will report back findings .