questions about top end rebuild

2-strokes-4-life · Jan 22, 2006

ok,i tore down the 125 today and looked everything over.i cant really find any flaws in the cylinder, still has good crosshatch and piston is in pretty much the same shape. should i just put on a new ring and put it back together or should i still get everything measured and have it honed first?also can i clean my power valve with it still installed in the cylinder?it moves freely and wasn't seized when i tried to move the arm i looked into the cylinder and saw them move from fully closed to wide open but they do have some carbon on them.also can i reuse the wristpin and bearing or should i replace those as well?they look fine also and the bearing rotates smoothly on the pin.thanks in advance for any advice oh just for the extra info,last comp. check showed 155 psi

+30 · Jan 22, 2006

I would put in a new piston if its been a while, but ringing it is better than nothing. I always removed my pv during a piston change, thats the only way i was able to get them clean. You can keep the wrist pin , I never had a wrist pin wear out you should be ok there, Id want to replace the bearing though if it has a good bit of time on it, cheap insurance. as far as measuring and honing, there is a lengthy thread on the matter on this site that shows varying points of view. Through 7 or 8 pistons on my 01 cr 125 I never honed, but a ring did migrate once catching a port and trashing the cyl, so each cyl had about 4 pistons without honing. If I remember correctly some piston mfgs recommend not honing, although I dont have proof of that statement, Ill try to dig up an old wiesco box and see if its on the destructions.

2-strokes-4-life · Jan 22, 2006

30+ thanks for your reply yea the piston has a good amount of time on it,i would say 50 hrs maybe alittle more. the current piston is a vertex would you happen to know if the vertex pin will fit a stock honda piston?i am goin with the stocker since as of right now i have enough money to completely rebuild the top end if i get my parts from service honda.i will def go ahead and replace the bearing,hopefully the pin will fit.do you think i should have the cylinder measured or just go ahead and install the piston?as stated befor the plating looks fine with a good crosshatch still visible.let me know if you find that info about the honing,thanks again :cool:

QKENUF4U · Jan 22, 2006

IMHO.........
hone the cylinder (look for thread that 30+ is talking about)
new piston
rings
pin
bearing
gaskets
your already there so ya might as well do it right

questions about top end rebuild

2-strokes-4-life

+30

2-strokes-4-life

QKENUF4U

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