Easier said than done. You'd need to impose BATFE-style regulations and measures. You're talking about arresting people for selling partially manufactured parts, parts which they claim are actually for other things, plans for parts paired with uncut sheet metal, etc. Is a clutch illegal to manufacture if it happens to fit on some model of two-stroke motor, even though it could also be used for other things? Have fun getting tangled up in these weeds. And the only way you'd stand a chance of enforcing this is by threatening people with many years in prison for what are non-violent crimes.
People tolerate this sort of thing in the case of the BATFE because nobody really needs a machine gun, very few people have one in the first place, there's little parts commonality with other machines and because machine guns kill people in very visceral and obvious ways. But with two-stroke motors you have a whole ton of people who use these machines to save on huge amounts of labor (you're fucking with the way they put food on their table and pay rent, not just their fun at a gun range) and the alternatives are subpar. You exempt chainsaws from this, but that merely reflects what you are personally familiar with and consider reasonable. And even if the alternatives weren't subpar, you'd still be asking people to purchase new expensive machines instead of performing cheap repairs on machines they already own. Point is, the incentive and willingness to skirt two-stroke spare part bans would be much higher than with machine guns. Your bans would fail without extremely draconian enforcement.