Hi Dustin.
From my point of view the intake on the 420/421 has been trouble free on saws that iv had through the workshop . I know what you mean regarding having a clamp as a preference but it seems not to be a problem due to the way the saw is constructed. The way i see it is like this.
As the motor and carb/air box is all one unit the rubber intake is subject to no flexing unlike a separate carb/air box intake boot arrangement . The intake itself having a chunky constriction along with a shoulder/shoulders that on install the carb floor mount/top cover applies holding pressure onto the cylinder intake that also has a groove cast into it for extra security and holding ability.
I would add that for best practice I make the choice of always using a new intake rubber if removing one from the cylinder. The need for multiple instals of the same new rubber is minimal for me as i'm not doing saw modification testing. Iv put a pic with this post for everyone who has not seen or worked on the 420/421.
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