Big-end wear.

Big-end wear is surprisingly difficult to identify. Mine appeared to be fine, no play to be detected untill I flushed it with petrol and, only when still wet with petrol, a discernable ''click'' was there. According to Phil Irving and others a clearance of 0.002" to 0.003" is acceptable.

Off course the only way to find out is to dismantle the crank assembly; anyone who would like to try himself should try this link.