140 to 150 psi on most 2 cyl Rotaxs. They tend to be a higher compression , higher torque, lower rpm running than most of the compitition. In years gone by. The other brands would rev higher but less compression. That has since changed. As long as both cyl are within 10% of one another you're good. But Rocketman 122 is borderline. Wouldn't hurt to put a set of rings in there.
122 is not borderline depending on the gauge. Check to see where the Scrader valve is. If it is not close to the end that screws in to the spark plug hole you have added volume in the combustion chamber and no matter how many times you pull you can not make the same compression in a larger zone.
This is typical of many cheaper gauges. A good gauge will have the Schrader vavle at the tip of the threads.
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