2006 YZ 125 crank identification

Hello guys,

My yz started to run really hot last time I rode it so I ran a leak down test on it and it failed, psi dropped from 6 to 4 is about 1 minute. So we are planing on replacing both crank seals and also a new piston.

We we pulled the cylinder off we noticed it was ported and also had a oversize piston in it. But the crank has these weird grooves machined into it.
Has anyone ever seen this before? I googled stock cranks and all the photos showed a smooth crank.

Any ideas on these grooves? Also when I got the bike the jetting was very rich, we bought all stock jets and got it close, but not perfect. Anyone has any starting points for 144 jetting? I live at 5000 feet.

Thanks