Changing the piston

[kyleblehman]

Hey guys i have heard from several people that when replacing the piston and rings you should hone (or something like that) your cylinder. Is this true? I cant imagine doing that everytime because eventually the cylinder would be gone. This applys to a yz 125

 

[1983yz80]

Depends how long you run on your top ends. I do it on my bike everytime.

 

[kyleblehman]

Well i only ride on our acres and ocasionally ride at a track. So i guess i dont need to do it cause iti snever run hard.

 

[BSWIFT]

Honing your cylinder will smooth small scratches from the cylinder walls. Deep scratches or pitting will require boreing(sp?) Even if you do regular top end service, you will eventually need to hone or bore the cylinder. Clean your power valves as well. Spooge and carbon build up can cause poor performance even with a new piston and rings.

 

[Woodsracer200]

YZ top end,

Make sure you have a machine shop spec. your cyl. No need to put a new piston in a worn cyl.You really should ring a 125 twice a year even at moderate riding level's.Also check into fractional oversized piston's,you dont need to hog material out unless it blow's up or gouge's the cyl.Check powervalve clearances,it may need modified depending on how much the cyl. is bored.One more thing,check crank tolerences,a sloppy crank will blow up a motor as well.Good luck,Bill.