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NICASIL issue (pictures)

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looks like the cylinder wasn't bored round,looks like there are places the rings didn't touch.

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seems like way too much wear for 4 hours too

no question, it is too much:mad: What would happen after 100 hours?

but why only the cylinder damaged? Wrong process of Nicasil application or really roundness issue?

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ring end gap checked? installed correctly and piston facing the right way? was there a prior failure that prompted this rebuild?

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That doesn't look like an issue with the plating and as far as the bore not being round, it's a lot harder to make an oval hole than a round hole. The boing process is pretty hard to screw up.

What was the piston/cylinder clearance when you assembled the new parts? Do you have a bent connecting rod?

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I've had a similar thing happen a few times with freshly plated cylinders from Millennium Technologies with around 3 hours of run time on them, just not as bad. I sent one back in and they said it wasn't abnormal wear, it was just discoloration and was fine to run. Weird for sure and unsettling.

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A forged piston in a new bore,? I'd say not enough warm up time for EVERYTIME it was started.

Although... the wear at the very top is a bit odd, I'd measure the cylinder to see what warpage there is.

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thanks for everybody the answer!

Sorry for a late reply but here was night:)

Both ring end gap was 0,35mm (acc.to the Wiseco rec.). Piston clearance was 0.05mm. Cylinder diameter is 68,01mm. (bike is WR250z 1995)

Piston assembled in a right way (arrow to the exhaust port).

I had not issue with a Wiseco con rod before, and was not changed now therefore think it is not the root cause.

Just a question for a "wrong warmed" bike: in this case why can see scratch only on the cylinder surface and not any on the piston?

(((I warmed up correctly the bike during the break-in and after before each ridinig. It takes about 10 minutes)))

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It looks like someone tried to hone it...

noone honed it. Cylinder in the picture was "freshly" removed from the bike

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DSC00333.JPG

In this pic, it almost looks like a ring gap in the wrong location, broken by a port when then scuffed up the liner.

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DSC00333.JPG

In this pic, it almost looks like a ring gap in the wrong location, broken by a port when then scuffed up the liner.

No. Ring end gaps were located to the intake direction. Ive always check the proper ring assembly from the intake port (without reeds possible to see) when put the piston into the jug.

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When you had the cylinder replated, did you send them a piston to size it to? That looks like a clearance issue to me. Hone it to clean it up, put a cast piston back in, check cooling system operation.

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thanks for everybody the answer!

Sorry for a late reply but here was night:)

Both ring end gap was 0,35mm (acc.to the Wiseco rec.). Piston clearance was 0.05mm. Cylinder diameter is 68,01mm. (bike is WR250z 1995)

Piston assembled in a right way (arrow to the exhaust port).

I had not issue with a Wiseco con rod before, and was not changed now therefore think it is not the root cause.

Just a question for a "wrong warmed" bike: in this case why can see scratch only on the cylinder surface and not any on the piston?

(((I warmed up correctly the bike during the break-in and after before each ridinig. It takes about 10 minutes)))

Ya,got a point there..The piston should have scuffs on it too.

Maybe some dust,dirt got by the filter? Check for grit on the intake boot after the filter.That would wear a cylinder but not leave a seize mark on the piston.

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When you had the cylinder replated, did you send them a piston to size it to? That looks like a clearance issue to me. Hone it to clean it up, put a cast piston back in, check cooling system operation.

they requested only some pictures about the paper box of wiseco piston. I think they have a central database or?

despite of fact I will put in prox (cast) piston and not forged one

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