Is this catastrophic?

[Chrisingippy]

Hey everyone,
This follows on from my tuning diagnostic help post..
I mentioned there today that I went out to the bike today to find fuel dripping from the exhaust!
I pulled the plug and rolled the bike back and forth ejecting all the fuel out the plug hole. I tipped the bike on its side to.drain more. When I stood it back up and rolled it again, the engine locked up.
I pulled the cylinder and found this first single piece in one of the crank balance holes that had been drilled, jammed against the housing.
The crank then spun free. Reassembled the cylinder only to have it happen again.
Piece number 2 fished out, I know there's a third as I saw it drop back in.

This motor has 40km on it. I rode it very briefly yesterday, pulled up and shut it off. There were no signs of any issues. (Other than tuning issues mentioned in my other post). Im not familiar with inside the crank housing to know where this is from. There is no cylinder, piston or housing damage to account for the chunks.

 

[Vikingimike01]

That piston looks terrible. I think theres more issues than that one little piece. But yes, you need to find out what happened. You may need a whole new engine...

 

[darwin]

If you do buy a new motor save the old one for parts.

 

[Oddball Matt]

Pull the wrist pin and remove the piston from the con rod, then flip the piston upside down. I'm guessing something, likely a bum casting, is making the sides of the pin "tunnel" crumble. Judging by the color those are not from the con rod itself but likely from the inside of the piston. I'll tell you if my guess was correct that engine was seconds away from a very explosive decommission.

 

[Chrisingippy]

Pull the wrist pin and remove the piston from the con rod, then flip the piston upside down. I'm guessing something, likely a bum casting, is making the sides of the pin "tunnel" crumble. Judging by the color those are not from the con rod itself but likely from the inside of the piston. I'll tell you if my guess was correct that engine was seconds away from a very explosive decommission.

You are correct about the con rod, its a bronze colour. I'll remove the piston and see..

 

[Chrisingippy]

That piston looks terrible. I think theres more issues than that one little piece. But yes, you need to find out what happened. You may need a whole new engine...

Why do you say that? There is no scoring or marks on it, the cross hatch on the bore is still visible too. The black marks on the side are just carbon from fingerprints..

 

[Chrisingippy]

So I went to remove the wrist pin and take the piston off and can clearly see underneath, that there is absolutely nothing wrong with it.
The metal fragments are also a different colour grey and seem a little porous. Im thinking it's the 'pot' metal that the case is made of. One piece appears to have a light thread cut into it.
I'm wondering if its the underside of one of the cylinder bolt threads. This engine uses long Allen head bolts into the case instead of studs.
I've contacted the seller and started a PayPal dispute so that's going to be fun..
Is it possible to buy engine cases if I get nowhere?

 

[Oddball Matt]

If there's threads visible you might well be right, too long bolt might have bottomed out and cracked the casing when tightened down. Didn't see any in the pics so went with the curved shape.

 

[Vikingimike01]

Not even my piston with 200+ kilometer looks so dirty and.. whats that red spot in the middle? Overheating?

 

[Chrisingippy]

Not even my piston with 200+ kilometer looks so dirty and.. whats that red spot in the middle? Overheating?

By dirty are you referring to the carbon? The pink spots i don't know. I can't see how.it could.have overheated. It's never done more than a 10 min run. First tank was 16:1 and just too oily fouling the plug and oil from the exhaust. Second tank was 20:1 and bike has always run too rich. Every run so far has been around the block once whilst I was trying to sort tuning issues out. There is no sign of damage anywhere on the piston or cylinder wall. The bike was running fine (apart from tuning) and gave no indication of problems. I came out to find the engine flooded with fuel, tipped it to get the fuel out and that's when the bits if metal got stuck in the crank..