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They just let water in more than other brands from what I can tell, I have to replace mine every 20 hours or so. I pack the shit out of them with grease, but water still gets in. Only solution is to disassemble the front end after you wash to get rid of moisture (and who the hell is going to do that?), or just buy a couple bearings and change them out every so often. I just use the cheap aftermarket ones, OEM doesn't last any longer.

Oem plastic is really hard to beat on these last gen kawis. Looking forward to following this one along! Here’s mine from a few years ago.

Myself and 3 friends owed 2019 KX450s new. I know every one of us has had multiple steering stem bearing rusting issues. I personally did 4 sets in 2 seasons on my bike. My first sign of rust on these bikes is when you take the bike off the stand after it sits for a few days the bars will be locked straight until you break them free. It's downhill quickly after that and they get extremely notchy, to the point where it can be pretty scary to ride, especially on rutted straights. I was surprised it would feel it...