# Piston HELP!!!



## tacoma_2002 (Jul 16, 2009)

Well not exactly the "sneak peak" I wanted to give you guys, but here it goes. I tore into my donor bikes non-running engine to find mounds of silicone and this....(Yes the piston was just that clean when I removed the head, so I'm guessing the bike didn't run long after the rebuild)










Can you guess what those marks on the piston are from? If you guessed intake and exhaust vave, then you guess right. Oh great....warped valves from a timing jump. I felt of the piston inside the jug and it had some side to side play (probably 1/16th")...oh boy...here comes rings. Pulled the jug to find it smooth as a babys bottom with no ring groove. 

However, I don't know what piston this is...I can't tell if its been bored or not, and from the HC sounds like a factory Honda part number, but by seeing the "50" I'm not sure if that indicates a .050 bore over... You tell me. 

Also....

The rod bearing has just a dab (not much at all) of slack (up and down) is this normal, or should I be concerned?


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## NMKawierider (Apr 11, 2009)

As I recall, yes it probably is .050 over but in my day as a honda machanic...some 35 years ago now.. I always saw that actualy stamped on the top. Is Honda still using the roller bearing rod bearings? If so, the play should be so little you can't feel or see it.


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## tacoma_2002 (Jul 16, 2009)

Its so little its "almost" un-noticeable, and all the oversize pistons I've seen have had it "stamped" on the piston top as well...and looks like they'd have .050 instead of just plain ol' 50....thats just my guess, but guessing don't cut it here.


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## NMKawierider (Apr 11, 2009)

Yeah..probably better mic it and see. Got the stock spec on the cylinder or piston?


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## tacoma_2002 (Jul 16, 2009)

Guess I'll have to dig around and find my mic and check it out. I'll let you know.


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## tacoma_2002 (Jul 16, 2009)

mic'd to a 73.xxx, so its a std. bore. Don't know what the 50 is about on the piston tho...


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## NMKawierider (Apr 11, 2009)

Well, at least you know know.


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## sprintertech (Nov 22, 2009)

rollers tend to not be as tight as babbit bearings....


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