Windowed piston

[DieselTech]

Yep that's what I've found this far. & another company now has a 47mm steel sleeve variant.

 

[Cannonball3]

Just for information, heres the rare 50mm G4 cylinder. Im guessing its a steel sleeve with out the liner.
This listing moved to a pic of the Sleeved cylinder when one tries to buy it. Notice the piston is a 3. I saw these
awhile back. Cant find them any more. This would be the set up to run. No sleeve blocking the transfers/ports

 

[DieselTech]

I might have found them lastnite, they were calling it a g4 big bore kit, I didn't know what they meant by that.

 

[Cannonball3]

I just bought one of the cylinder kits, for $30 why not. Appears to be a low hole piston. Dont remember what my PK80
is. I believe a short rod so it should work.

 

[DieselTech]

True pk80 I thought were 40mm stroke long rod engines. BGF has G4 & G5 cylinder kits for $32-$35 I believe.

 

[Cannonball3]

Well couldnt use the pk on the Minarelli as it came up way short in the hole, so assuming its a short rod 40mm stroke.
I would have used it otherwise instead of the Zeda.

 

[Detroitbradster313]

I make my own just use a angle grinder or dremel and cut my own window out, the full width of the intake. I found that the more air it can get thru the better so the bigger less restricted hole worked best for me

 

[Detroitbradster313]

I can't find non windowed ones either...

ebay has everything

 

[Karl Snarl]

I make my own just use a angle grinder or dremel and cut my own window out, the full width of the intake. I found that the more air it can get thru the better so the bigger less restricted hole worked best for me

I'm sorry for laughing I just couldn't contain myself, but that's not going to last very long. You can try it, but I got $5 bucks it self destructs sooner rather than later.

Piston needs support, and rides along the cylinder walls on the skirt.

 

[Cannonball3]

it would seem to me there is a formula for window size. Too big and you can stall or greatly slow the flow. As I have said the twin window piston runs no better, maybe not as well as the single window I made my self. Also removal of an area of the piston has to reduce primary compression as it material below the rings. Thats why tuners stuff balance holes, cases and even wrist pin holes. A big gaping window has to lower primary compression some. There has to be a balance between the two. The windows also I think would be subject to timing/duration. Cutting a big hole in a piston will work but just like all two stroke tuning there is much science behind it.