Rebuilding an iame X30 top end

I feel i am a pretty competent small engine mechanic. Ive rebuilt TONS of 2 and 4 strokes but im out of my realm in terms of the X30 engine and am looking for some insight.
I kart on a club level budget and yeah maybe the rotax would have been a slightly more logical choice but frankly the simplicity of the x30 made me grab hold and not let go. I play with carbs all day at work, last thing i want to do is play with carbs racing.

Im closing in on 8hrs on my top end and feel i can tackle this myself over the winter and save myself a lot of money. 2021 id send it out for a top/bottom build though.

My main questions are in terms of the cylinder. For dirt bikes, atvs, mowers, blowers, etc (as long as they dont grenade) id just measure the piston size, buy the next size up piston and have a respectful shop bore and hone cylinder and id assemble it. I dont think thats the case how it works with these engines??
Ive found the manual with clearance specs but it doesn’t say anything about the factory specs of new parts so im a bit dumb founded as to how to know what size piston i have/would need as to who to have the cylinder bore and honed as well.

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Have you ever tested the main bearings? My procedure is to put a dial indicator on the crank and try to move it, by hand, up and down. No movement at all indicates good bearings, more than .001" or .002" indicates to me that the engine is in need of new bearings. At the same time, using a .0001" indicator, check the crank run out. More than .0002" is bad. None is best!! No engine of mine ever went more than one race without checking these things. Probably not totally necessary, but I never wanted to leave anything to chance.

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If I recall correctly there are two “color of dot” of pistons with respective clearances and those pistons display the BORE size on them, vs the actual piston size.

@Mynameismcgyver, can you add some insight?

To tack-on to what Alvin said, for sure checking everything else is prudent.

Main bearing endfloat and axial play.
Rod ends for signs of overheating.
Reed condition
Squish after assembly

If you are running an out of the box engine and are happy with it’s performance, it’s a pretty easy job if you have the right tools. To replicate a factory build:

1). have the cylinder honed (on a real honing machine, not a drill hone)
2.) measure the finished bore and fit a piston that is .11mm/.12mm smaller
3.) replace the stock .40mm base gasket

The above specs will not maximize performance, but will provide an easy to tune, long-lived (relatively speaking) motor that will never fail tech. If you want maximum performance, you will need to have the engine “built” or, at the very least, play around with different piston clearances and base gaskets. You can send your cylinder the Comet Kart Sales and they will hone it and fit a piston for you (I do not provide this service). I suspect they will provide a factory spec piston size, not what they would use on a fully built engine.

I have updated my website with what I hope is a sensible explanation of how Iame marks their pistons. https://foxandsonkarting.com/iame-piston-sizing

I really appreciate the help everyone! I believe i have the understanding and information needed now. Cheers