Topic: Piston is chipped...Can I still use it?

[thomellis]

Hey Guys,

Newbie question...So one of my pistons has a bit of a ding in the top of it, and I have no idea if it's okay to reuse or if I need to totally trash it.  Can it just be filed down, or is that a terrible idea?



Thanks for any advice you all can provide!

[nayto550]

If it was a small chip in the middle of the crown, I would hesitantly say it could be reused.  With the chips out of the edge as it is, I would highly recommend replacement.

[mycb750k6]

What bike, year, piston?
What does the cylinder look like? Pictures...

[thomellis]

Thanks guys.

The bike is a 72 CB750, I can get a picture of the cylinder tonight.

Does anyone know if a 76 piston is the same specs?

[nayto550]

The next important questions are:

Why is there a piece of the piston missing and where is the missing pieces? 

[thomellis]

I have to imagine it happened after it was pulled for a couple reasons:

1) its super clean where the nick is, no carbon build up
2) I didn't notice it until a couple days after it was pulled
3) the neighbor kid who loves to run amuck in my garage swears he didn't do it

[mycb750k6]

76 will work or I've some pistons you can have or others here will give you one. Decide what you need and let us know.  In any event you'll likely need  a new set of rings and hone the cylinder. Let's see the picture of the cylinder first and what's the mileage?

[trueblue]

That piston could be used in a pinch, you would need to remove any rough edges with a fine file and make sure the top ring groove hasn't been dented but ideally you should replace it.

[Xnavylfr]

Looks minor to me also. I would use sandpaper and just knock the burrs off the edge and use it.


Xnavylfr(CHUCK)

[Raul CB750K1]

I would also reuse it.

[phil71]

that kind of mark was caused by something out of whack. Are you sure that piston belongs in that engine? Looks like a deck height thing.. unless the valve timing is way out of whack. Cam chain shot?