Best Top End Rebuild - OEM or Aftermarket Stuff?

This winter I will be rebuilding the top end in my 2012 KX450F (actually, a very reputable guy that does mx engine rebuilds will be doing it for me...). 


He is suggesting using either OEM, Pro-X or Vertex components, but does not like Wiseco.  I tend to think that is a builder's preference, or frankly, where he might get the best pricing or whatever.


He said that as part of the top end rebuild process, he will cut the seats, hone the cylinder, new camchain, set shims, and reassemble.  If the tappets, seats or guides look worn, those will have to be addressed, but probably not likely. 


The bike has run spotless for 50+ hours, but I crank on it pretty good and am doing this for preventative maintenance.


My thought is to just stick with OEM stuff and be done with it -- the stock bike has plenty of power and runs great.


However, I just have to put it out there and see what others might recommend from experience.  I don't necessarily want to go to a higher compression piston, simply because I think that adds heat (higher engine temp) and I really don't think it is necessary.


I just figured, since the top end will be apart, I want to explore a few options and see what kinds of suggestions anyone might have.

I rebuilt my top end with all oem parts and have never had problems , I had 120+ hours on mine before I rebuilt it, had to put new valves, piston still looked pretty descent though.

I went stock on my 09 rebuild. Although, I did do a '10 piston setup. No problems.

OEM. Over 400+ hours on my 12, and have only gone through two top ends. Have had zero problems...valves are still in factory spec. 

Hey guys, thanks for the responses - three responses, three OEM recommendations.  Sounds like the safe and reliable way to go - you guys with 120+ and 400+ hours have me feeling pretty confident about the longeivity of this bike!


Any other comments would be appreciated, thanks --

This bike is amazing, all my hours are desert hours with 12-15 races a season and Baja prerunning, and still beats all of my friends brand new bikes in the power, handling, and badass departments haha

Just maintain it!!

Hey xtyharvey53, I hear ya...I have buddies that have ridden my 2012 KX450F and they can't believe how much power it has...they actually tamed it down a little for 2013 with slightly different cam profiles and added the sketchy air forks...I think that 2012 bike is pretty awesome once you get it set up to your preferences for handling and suspension.


I tweak a lot of things setup-wise, but have never touched the motor -- just change the oil and air filter and keep up on the regular stuff, it runs great!

"Learn to control the throttle, and this bike can do anything." Dirt Rider said it best! 

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