YYH has way higher power lvls than OP. Anyone who isn't Logia gets mudered pretty easily.
As for kenshiro who is a close range fighter, he only need to touch enel to blow up his internal organ, if he get a strike at his chest or head its game over for enel
I've never read Fist of the North Star, but what exactly are Kenshiro's abilities ? If all he has is physical might he won't be beating Enel. Enel, being a logia, is immune to physical damage of any kind. There are only 3 ways to harm Logias: Infusing your attacks with Haki, Sea stone to Null their powers or by using their counter element. Luffy was able to beat Enel because his body is rubber, allowing him to actually land hits on the guy. On top of it all Enel has Mantra, which allows him to predict his opponent's moves.
Edit: After some research into First of the North Start, I realize that Kenshiro can beat Enel thanks to Muso Tensei. But only because of that, seriously that shit is way too fucking broken.