[mpiro]

So learned the hard way to always replace with Honda parts this past weekend. I don’t think a piston is supposed to look like this but that’s what I get. Yes everything was installed properly but just wanted to let people know what has happened to mine.

I kid you not, I wish I got a picture when the cylinder was still on, the piston was in sideways with that folded side dug into the cylinder wall.

So now to go pay an arm and a leg for Honda stuff

 

[cmanningjr]

Ouch!


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[SlammedRanger]

Yeah i learned this the hard way aswell. About 15 years ago when i was a kid racing a blaster we put a namura piston in it and without warning and for no reason the skirt broke off one side and went into the bottom end like a missile. Exploded into a million pieces and destroy the crank, both case halfs, and atleast 3 or 4 transmission gears. We junked the whole motor and started over. Quad ran great for about half a season and i wasnt fast at all so i was far from hard on it lol. You live you learn and you buy wiseco haha!

 

[YukonXL04]

Hmmm I have a namura in mine right now. Guess I'm gonna have to change it out

 

[TBRider]

Wiseco is the only way to go.

 

[mac102004]

I’ve been trying to tell people that these pistons are nothing but cheap Chinese made scrap metal but nobody on this forum seemed to believe me. I doubt your going to change anyone’s mind here even with pictures.

You don’t need to buy Honda OEM to get good quality. Shindy makes good pistons that will meet or exceed OEM quality. Then of course there are aftermarket brands like CP, JE, Wiseco etc that make high quality forged pistons that are much better than the cast OEM pistons.


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[fishfiles]

I don't have any Namura experience , I always get Shindy , have heard that Shindy is the OEM manufacturer , but it was a hear say rumor -------- but looking at that piston failure , I would speculate the crankshaft/rod is bad and helped caused that failure

 

[alloutdoors]

Wow! What a mess and would suggest looking down into the block to ensure no pieces, etc., are in there after that aftermath vs. just addressing the top end only. Best of luck!

 

[machinecrook]

Good to know if ever I need to change the piston! Thanks for the heads up even though it was to your misfortune

 

[Jeepwm69]

I use Shindy too. Made in Japan.

 

[XplicitRacing6]

Holy cow! Your piston looks like a piece of cardboard... thats crazy
I've always used Wiseco, never had a problem with them

 

[dr. feelgood]

I like Wiseco kits; I've put quite a few of them in various size motors.

Rob

 

[whiskerfisher]

How long has that piston been ran in the engine? Is it stock diameter or has it been bored oversized?
I have built several race engines in cars in the past and that defiantly looks like you had excessive clearance between the piston skirt and cylinder wall. When you have a "loose" piston in the cylinder, it slaps or wobbles in the cylinder wall and potentially weakens the piston skirts and well... your pics are the catastrophic results.
If I had to guess I'd say your piston was the wrong size for the cylinder diameter.
Also what size ATV did that come out of? Looking at the size of the piston compared to your hand, that piston looks huge!

 

[wheeler]

I had good luck with a Namura piston. It was an oversized one that I installed in my wifes Timberwolf 250 4x4. Ran like a champ for years after. Once I sold the quad to my brother inlaw, it made it 3 more years until he tortured the engine to death....

 

[fishfiles]

Something else took out that piston more than the pistons faulty , like mentioned maybe a bad bore job , bad rod ends , bent rod , bad crank bearings , something had it throw'ed off