Spring loaded chain tensioner???? Hawk KPX ?
 

I see a lot of inexpensive spring loaded chain tensioners on Amazon, and AliExpress. A lot seem to be universal, BUT I never see them used on these bikes. Is there a reason they don't work? , or are they just junk?
If they are worth getting, could someone recommend which ones to get ? I have a Hawk, and KPX. Thanks

Spring loaded chain tensioners were far common back before manufacturers realized that placing the countershaft as close as reasonably possible to the swingarm pivot minimized chain slack variation throughout the articulation of the rear suspension. This problem, when it existed, was significantly exacerbated by longer travel suspension. Hawks, and other Hawk-type bikes don’t suffer from a great deal of chain slack variation. That being the case, a spring loaded tensioner isn’t really necessary. Installing one wouldn’t provide any real benefit.

I tried one, and it lasted about 2 weeks and I took it off. In theory it's nice to have because you can leave the chain a bit on the slack side, or it can go a bit too slack over time and you won't immediately suffer from throwing chains. As far as controlling chain whip is concerned, they do work ok, but not as well as you might think. It really depends on how strong the spring is. Too strong and it can cause increased chain and sprocket wear. Too weak and it won't really do much of anything other than cost you money.