Thanks for the open reed info.I have a picture of the intake side of A Mac 91b & it shows 2 ports in the cyl.wall appox. 1 x 1 1/2 inches.Is this the only mod.req'd.? How critical is the location height from the bottom of the cyl. wall.It seems to me that the intake flow is much greater than the exh...

Can any of you guys explain the open reed engine.Sounds like a good winter time project.
thanks,Gene