Yamaha sr125 piston question?

[Spanner]

So, I was stripping down my engine, got to the piston and discovered that it had what appears to be a dent (what I'm pointing at with my screwdriver). This is the first time I've done any engine work so I am a little unsure if it is meant to be there or not?

 

[xb33bsa]

I think you will find it lines up with the sparkplug, extra clearance is what it likely is
be careful cleaning pistons many people over do it whatever you do do not try to wire brush the ring grooves or skirts only use solvent a soft brush and air

 

[cosworth]

He nailed it. It's for a properly indexed spark plug. The flame front needs to be in the optimum area for the squish to work.

 

[Spanner]

Right, ok thanks guys