125-200cc Piston interchangeability CR/WR Yamaha YZ 125 2005 onwoards

Hi there,
i just came across this, i recieved a brand new Piston for my WR which i put next to my YZ 125 Piston- its looks so similar- i m sure it will fit vice versa.
Has anyone tried this before?

I would say its the Same But the YZ piston has got 2 holes drilled in the skirt to cool down the exhaust bridge.

You will need to machine your head to fit the yz dome. Other than that the yz piston works great.

The YZ 05- has a flat top piston.
the pre 05 YZ has a dome Piston.
But this one has a small angle around - looks like a "squish area"

is the relief area above the wrist pin just for weight reductions or is there any porting to that? looks pretty damn close!

The shop that handles my suspension had a earlier wr125 and dropped in a big YZ 150 piston after they punched it.
He said that it was a dead swap as everything fit

All the later yz pistons have the bevel to a flat top. The top is raised ~.026" above the top of the Husky piston. If you don't machine your head accordingly the squish will be too tight at the top of the bevel. It will also raise your compression quite a bit. It will want to detonate around the perimeter of the piston because of the trapped gasses that will be at greater pressures than the combustion chamber due to the very small squish at the top of the bevel.

I used the YZ specs for my 165 pistons. I like the piston design. It has a 1mm offset that also helps. It is just a matter of machining your head to get the squish and shape correct. Head machining is cheap and allows you to use the cheaper and more available YZ piston for the rest of the motors life. You will be creating a mirror image of the piston bevel to flat top at the correct squish when you machine the head. I would also consider enlarging the bowl slightly so you don't have any fuel issues with too high of compression.