What's a new top end consist of?

[viking]

I am a newbie! I ride a thumper, but bought a yz85 for my son last April. Prior to this the only experience I have had is with his old TTR-90. We basically ride in fields around our home and ride on Michigan trails on weekends. I have been told that 2 strokes need new top end's every year or so depending on how the bike is used. I am not totally sure what exactly a "top end" rebuid consists of? Thanks in advance for the input!
Eric

[ddfh_4_life]

It consists of a piston, ring(s..not for the 85 though), circlips, wristpin, bearing(not always, but good insurance), and gaskets. Also you should clean up the cylinder, and the powervalve, but the yz85 doesnt have apowervalve so no worries. Of course you have the coolant to replace, also, but thats no biggy, you do it when putting the engine back together.

[Silver_Fox]

Hey, welcome to the forum.

DDFH summed up the topend parts list, some guys just re-ring it, but I think if you got it apart you better replace the piston as well.

Top end rebuild is pretty simple, usually 1.5 - 2 hr if no problems.

[SirFallsALot243]

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That thread sums what it is and how to do it pretty well.