The GO .18 engine is a sport engine with a pullstart from what I can see on their website, for that reason they cannot be a tight fit from new because the cord would break if the motor jammed during run-in startups.

Yes they will need to be run hot to get the sleeve to expand and help relieve the stress on the piston and rod, unfortunately that means less lubrication because of the leaner setting to get the heat up.

We appreciate (Rex Shane and I) you want to defend the brand but we are just giving our constructive opinion from years of experience running .21 race engines and having owned a few generations of GOs.