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Which
way does the piston & cylinder go back in.
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Some engines have
transfer ports through the piston as seen here and the picture
below. This is a Schnuerle ported RJL K.61 and it has a large
transfer window in the piston for the boost port. These ports
in the piston are always opposite the exhaust. If you were
to put this piston in backwards all the crankcase compression
would leak out and the engine will not run.
READ
ABOUT RING INSTALLATION and end gap location.
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This
is a loop scavenged, cross flow piston & cylinder out of
a K&B 40. This has the transfer holes in the piston and
cylinder. I refer to these as cheater holes because you can
increase the flow through the bypass without altering the crankcase
casting. This trick has been done for 60+ years. |
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You
can always tell a loop scavenged engine by the baffle on top
of the piston. On a loop scavenged engine, the baffle ALWAYS
goes opposite the exhaust ports. |
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The
exhaust port or ports are always symmetrical and are ALWAYS
THE HIGHER PORTS. Closer to the top of the cylinder. Like this
example you can see the "cheater holes" on the left
and the higher exhaust ports on the right. |
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Sometimes there
is no web or bridge between the exhaust ports, so you only
have one wide, rectangular port.
WRIST PIN with
pad
Usually the wrist
pin with a pad will have the pad opposite the exhaust. The
pad must always run against a portion of the cylinder. I can
not pass over an open port. If it does it has the possibility
of popping into the open port and causing damage.
WRIST PIN with
snaps
This wrist pin
can be installed either direction.
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slot on the top flange of the cylinder is for a manufacturing
process on ABC cylinders. The sleeve is located in a fixture
and the bore finished to facilitate chroming. Chrome is applied,
then the sleeve are placed in the same fixture to final finish
by ID grinding of the chrome. The fixture is not removed from
the machine from first grind to final grind after chroming.
Concentricity is critical to remove such a small amount of chrome.
The slot to pin in the case is not the main purpose and all
of the engines we produce do not have a pin in the crankcase. |
