This is a cast piston removed from a buddies quad. The majority of the damage is on the intake side. What do you guys think would cause this type of failure?

Pilled it and killed it???

My guess would be lean .

That's a timing burn. Now what CAUSED it to be grossly over timed is another matter

2 stroke mix or injection? 4 stroke?

Ouch Trent

does all 8 pistons show some of the same thing or just one ?

QUAD people....

I'll go with oil consumption to the point it started to become a fuel..... black death.

Is that the remains of an oil ring? Looks like a 2 stroke piston to me otherwise.

I've seen 2 stroke pistons from a 440 Rotax that looked like that except they were beat right to the wrist pin. Diagnosis was easy. Bad nitrous/methanol tune.

A few details wouldn't hurt...

Kevin

This piston is from a single cylinder, air cooled, 4 stroke quad. That is the oil ring but is filled with aluminum at this point. The cylinder wall has aluminum stuck to it and the exhaust valves were hung open due to aluminum build up on the exhaust stems.

This is a buddies quad which he has had for several years with the exception of loaning it to a friend prior to this last trip to the dunes where it suffered this failure.

Given the substantially lower elevation of the dunes, my first thought was a lean condition but supposedly the jetting had been corrected.

I'm thinking this looks more like detonation but the fact that it is offset to the intake valves makes me think there's more to the story.

On quads, I'm not sure ignition timing is all that adjustable. At least not commonly adjusted that's for sure.

A lean condition makes the most since, detonation due to incorrect timing looks more evident and lastly, getting sprayed at some point doesn't seem to far fetched in my opinion.

Just doesn't look like a normal failure to me and I think he either needs the rest of the story from his friend or he better start looking real good for the cause.

What are your guys thoughts? Doesn't this one seem weird?

If it was a 2 stroke, I wouldn't even have to ask why it blew up. It's what they do.

I actually have a CR500 I'm getting ready to put back in a quad. I think it's been long enough that I'm ready to give the two stroke another shot. I'm sure it'll be in pieces again soon enough though.

air cooled 4 stroke...most likely got hot, or lean.

we run 2 strokes as well, a 250r and a banshee....usually get a few hard seasons out of them. then a fresh hone and $200 wiseco piston kit......can't beat a 2 stroke! brappp!!

It's a cheap cast piston that was run hard lean, probably has a gummed up carb. I run alot of dirtbikes/4 wheelers/snowmobiles and with today's gas I'm always cleaning carbs from them sitting on off seasons. I did the exact same thing on an old 2 stroke snowmobile that someone gave me, except it blew a hole right through. It sat for 5 yrs and when I started it up it ran pretty good and against my better judgement I decided to take it for a ride just down the street wasn't even a quarter mile and it started running like crap, barely made it home before it quit.had aluminum everywhere.

Non-ethanol gas is your friend with small carbed motors. Water and ethanol will separate out and that stuff will leach the copper from the jets, changing them. I bet the carb has a bunch of green stuff on the inside of the float bowl if that is the root cause.

I was going to ask what fuel is used , if it's E10 then it's probably from being lean.

1 cylinder or 2?
Air cooled or liquid?
Fuel used?
2-stroke oil used?
Mixing ratio?
Ignition setting / timing?
Operating conditions?
How long on that piston & rings?
Iron (boreable) or Nikasil bore?

Didn't burn a hole through the piston crown, but the heat sure toasted the ring land... and the skirt is just plain ugly. Is that the exhaust side of the piston shown in the pic? Did it hang a ring in the port?

How about sucking in allot of sand thru the air filter if it has one?