TuckerBag wrote:
VERY basically the question being asked is:
I have a part that is half worn (=half new?), should I use it.

No worries mate, not easily offended, but the question is from someone who does a fair bit of 2 strokes but never had to deal with this tight of a clearance, for example on a Vespa ring gap is 0.5mm with service limit of 2mm! I ran them in the past at 3mm with good power (for a 50 year old Vespa) and always matched the pistons with much less precision, you know 150cc, 4-6 hp @ 6000 rpm... they run forever. Seizing a hole is followed by a light hone and scuffing a piston, then re-assembly and fixing an air leak or checking the timing. Unless it's a performance top end the damage is always minimal.

So now I have this .005 mm increment in the bore size (Vespas use .2mm oversize step) and I don't know how important (or unimportant) it may be to get it right.

Also my question is can the used pistons be re-used from another cylinder, not weather my original piston is any good. I also want an answer to the noise I was hearing, what does the worn out piston sound like? On a Vespa it gets louder when hot (air cooled) and what I have does sound like piston slap but I don't want to shovel money in to this bike replacing everything