I thought the hole above the exhaust port was to act as a decompressor at cranking speeds , if anything it would make the idle worse .
2 stroke compression figures ( like 9.5:1) are static figures ie ,if you do the maths , in motion the effective comp ratio depends on the porting to some degree. At cranking speeds you have to wait untill all the port windows are covered by the piston before any compressing happens , at faster speeds the fuel mix is delivered via the transfer/bypass ports to the combustion chamber at a partially compressed state and the effective comp ratio goes up and thusly some engines will tolerate a lower static comp reading and still run fine . Typically a 2 stroke with to lower comp will be a pig to get to idle /off idle properly and will probly be a poor starter.....particularly when hot .
At the end of the day you are the judge on that , If your happy with the way it starts and runs then it has enough compression
