Sandblaster I tried to send you a pm don't mean to jump in to your thread I'm new here but have been riding and working on 92 kx5 for 14 years. I just had a question about the kx5 center piston window mod from someone who has road with oneach first hand. Did the mod help you bike? Thx
Hello.
Yep, I got the PM late last night but didn't respond because I was beat.
I have rode both pistons.
It is highly unlikely that you can feel a difference.
The biggest reason for the mod was cooling.
Stewart (The last speed record holder) developed this mod for the KX500 to decrease temps around the crown of the piston at sustained high speed WOT runs.
It does not make any HP but it will help keep the HP at it's peak longer.
There are other potential benefits such as better lubrication of the wrist pin ect.
So, should you window your piston?
Mmmm... for most it isn't required but it's not going to hurt a thing if you do but don't really need it.
On my next build I will be putting some holes in that area, but not a big hole