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Does my piston look ok? Do i need to replace it???
The motor ticks but chain and valves and tensioner are fine
The motor ticks but chain and valves and tensioner are fine
Does my piston look ok?
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Ok. Is the burning oil a big deal? How do i fix this?
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2,608 Posts
I'm just as curious about the cylinder walls . . . .
Rick
Rick
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I tore it down because i am going to rethread the cylinder head cover bolts because over half the threads in the holes are stripped
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I see some chips missing on the piston rim, so?? that might bother me, as if that metal came off running and got down inside, it could have the sides all messed up
, Like mac said, need to see the sides of piston and walls of cylinder to be a better guess here?
, Like mac said, need to see the sides of piston and walls of cylinder to be a better guess here?
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you cant go by just look. measure your piston to bore clearance, is the bore out of round? how do the rings look? cant tell by the pictures how the oil rings are doing.
how does the other side of the piston look? any dark coloring, if so that top end has been overheated, almost guaranteeing your cylinder is out of round.
get that cylinder and piston off, take it to a competent machinist. you'll be glad you did in the long run.
BTW, I would strongly recommend valve stem seals at bare minimum while your in there.
how does the other side of the piston look? any dark coloring, if so that top end has been overheated, almost guaranteeing your cylinder is out of round.
get that cylinder and piston off, take it to a competent machinist. you'll be glad you did in the long run.
BTW, I would strongly recommend valve stem seals at bare minimum while your in there.
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Why valve stem seals? Are mine bad? Piston looks good, no dark coloring. How do you measure piston to bore? The rings look fine
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Ok thanks alot
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Hard to tell in the pics but it looks like some of that scoring on the cylinder wall is fairly deep? I don't really like those chips in the top of the piston either but I've run worse...like manny said it is worth measuring it now that it's off the machine, if your really in doubt buy an oversize piston and rings for it, it's not going to hurt anything and at least you'll be confident that the motor is at 100%....
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The labor is done so I would just replace and address anything you suspect needs attention.
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Just because the tensioner and chain feel fine dosnt mean they are. I would bet that chain is stretched and thats why your hearing a tick. When the chain gets to a point where the tensioner cant keep tension on the chain anymore it will tick. Pop a crf450 timing chain in and never stretch another one again. And that piston looks exactly like the 5 sitting on my work bench. Stock 400ex piston. Weird thing is the chips missing at the top. And what looks kinda like crosshatching in the cylinder still. Almost looks like someone tried to just hone and re-ring it and didnt use a normal ball hone or something. Kinda weird. Could be the camera playing tricks with the eye though. I would take everything you have to a competent machinist and have them inspect everything. The reason you change valve seals also is because your right there, they are cheap, and worth every penny.
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bottom left of piston in first pic, looks like a large chip is missing from the edge at about 6 o'clock ?.
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