Reuse piston?

[zrxrider]

I'm trying to figure out what to do. I have this new to me 2000 yz125. Its fouling plugs but runs well when it starts. It was never rebuild so I figured i'd pull the topend to take a look. The piston looks great with no marks at all, the cyl. still has the hone marks. The ring end gap was like .035 or so. Also there was a LOT of "goo" under the cover for the power valves. Do you think the ring was just really bad?? Would it be ok to just replace the ring, hone the cyl., add new gaskets and call it a day?

 

[flyingfuzzball]

i would totally rebuild the top end that way if it was still fouling i would know that its jetting and not something else.

 

[jsantapau]

measure the piston(or find someone who can) and that will tell you if it is worn

 

[Chili]

With unknown use and for the cost of a piston I'd replace it if I was already in there. Sounds like the bike is jetted really fat and needs to be leaned out.

 

[zrxrider]

Its 100% stock. Even the air filter was original. When I rode it, it pulled perfect with no flat spots etc. It kicked over pretty easy but I didn't do a compression test. I guess i'll wait for the manual to get here so I can look up the specs.

 

[Pete Payne]

replace it !

 

[_JOE_]

No doubt, replace it.

 

[zrxrider]

OK, you talked me into it. I will replace it. ANY problems with a std. Wiseco kit? I like the fact you get everything in one shot.

 

[Chili]

Wiseco is fine.

 

[_JOE_]

Wiseco hasn't ever let me down.

 

[Pete Payne]

Wiseco !

 

[zrxrider]

I was going to get the Wiseco kit but found a NAMURA Piston for $46 delivered. Anyone run these before? I did a search but didn't come up with much feedback.

 

[_JOE_]

Most often the old saying "you get what you pay for" isn't too far from the truth. Does that 46 bucks include gaskets? Pin? Bearing?

 

[zrxrider]

Does that 46 bucks include gaskets? Pin? Bearing?

No gaskets or bearing. Just the piston, ring, pin & C-clips. I have a gaskets already so just need the bearing. Its seems they are hyperutectic which is stronger than oem cast but not as strong as forged.

 

[zrxrider]

Well I got the Namura piston yesterday. :yeehaw: Looking it over, it looks very nice. It didn't have any paperwork for the ring end gap so I went with the OEM specs which were .5mm-.7mm or .020-.028. I filed them to the min. of .020 and installed it. A few kicks later and she fired right up and sounds perfect. I didn't ride it yet but just from revving, it feels much stronger. :ride: