New pistons inspection

[centaurus]

Hi all,

After months (or better said years ) of trials and tribulations (we are not going to go into whys and hows now), I finally got to the final stage - the parts for a top end rebuild for my NSR250 have arrived and I'm about to put them in.

However, I am a little bit worried. One of the pistons doesn't have a perfectly smooth surface. Although the upper face has a full shiny coat, the surface has small pits, it's not smooth. It is obvious the piston has never been used and these pits are from manufacturing (they are imperfections in the coating surface, not holes through it). These pits are really, really small. Is this ok, or it should be totally smooth?

I will post some pics tonight as soon as I get home. This is my first top end rebuild so I am trying to make sure I get everything right.

Cheers

[centaurus]

Te pictures are not clear unfortunately - the surface is shiny so I coudn't reproduce it very well in the pictures.

In the first picture, closer to the outer edge of the piston from 3-4 o'clock all the way to 7-8 o'clock

In the second picture, only two are visible - the one at 4 o'clock and the one at 7 o'clock.

They look like if the surface would have been soft, somebody would have poked it with a needle and made really small dips/depressions in it.

[Sketchy_Racer]

That's normal and nothing to worry about.

The tops of pistons exp two stroke pistons are very rarely machined. Only racing or high performance motors need it.
The surface is what occurs in the casting process.

[centaurus]

Thanks Sketchy. You put my mind to ease.