YS 140 FZ Question

[George Kennie]

I have one FZ and 3 L's, and I haven't measured anything, but I feel
very strongly that my FZ is the strongest motor of the lot. The Fz
is in a 12 pound airplane that goes vertical with more authority
than any of the others in 10 &1/2 pounders. I have to admit that it
is still a little overcompressed despite the addition of 2 head
shims. It will probably throw a rod one of these days, but it has
given me an awesome ride.
G.

Lem Stevens wrote:

>   I have a 140 FZ that I bought at a swap meet, so I do not know
> its vintage.  The top of the piston is the expected flat disk. I
> had a 140L, before this, that had ports through the top of the
> piston to the inside of the ring.  Apparently, as pressure in the
> cylinder builds, the ports press the ring out against the
> sleeve. Do the new 140 FZs have this ported piston?  Can anyone
> say what kind of power boost can be expected with a ported
> piston?  Just curious. Lem


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