Before you start the whole process, take the plug out and find out where BDC is and mark it on the flywheel (I used permanent marker). What I did (and still do) is whenever it's time to let the engine cool down (or when I am done with playing), manually turn the flywheel so that the piston is BDC so both the piston and sleeve has a chance to contract. IMPORTANT: don't touch the exhaust (mufler)
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Just a thought.