Cylinder windows

[paulwes83]

Hey guys,

Sorry if this has been answered already, but does it matter where the cylinder windows face in a gearbox, front or back?

I'm installing a lower compression cylinder for a shorter barrel and it has cylinder windows more to one side.

Please let me know and thanks for your time.

[TCLP]

Rear. The cylinder cannot seal while the piston head has not passed the port/window. The seal is a major part in the compression of your gearbox. That's also why you see that port/window in different positions on different cylinders to change when the compression starts. The farther forward the more air loss meaning less air around the bb and reducing FPS.

[paulwes83]

Thanks man, that 's what I figured and I feel like such a noob asking that, but I saw one version of "windows" where they cut tiny little squares right out of the end of the cylinder rather than further along.

Either way, thanks for clearing it up and giving a good explanation.

Originally Posted by TCLP

Rear. The cylinder cannot seal while the piston head has not passed the port/window. The seal is a major part in the compression of your gearbox. That's also why you see that port/window in different positions on different cylinders to change when the compression starts. The farther forward the more air loss meaning less air around the bb and reducing FPS.

[TCLP]

Yeah no worries. Basically the job of that window is to have equal volume as that of the barrel. The longer the barrel the father back or lack of window/port.