how much piston clearance is acceptable

I have a 93 geo metro.I have a knock when it is warmed up.When you rev it above 2000 rpm it rattles it also putting oil in air filter.I was wondering if I could get by with pistons to block clearance of 8-10 thousands.It has a small ridge at top of cylinder.I think the noise was rod bearings but the cylinder clearance is a lot more than is recommened.The rod bearings were down on the copper.Do you think i could rering or should I have it bored. thanks phil

Factory manual says .8 to 1.5 thousandths. You definitely need a bore and oversize pistons. I've never heard of such wear in a Metro engine though, what happened to it, 10W-40 oil?

Factory manual says .8 to 1.5 thousandths. You definitely need a bore and oversize pistons. I've never heard of such wear in a Metro engine though, what happened to it, 10W-40 oil?
I thought there was too much clearance but every body on the forum were just reringing their engines thanks phil