I)Cylinder heads: So lets talk a little about cylinder heads
and how they work and why!!!!!
*Its important to understand that the volume
of fuel vapor and shape of the head when
in proximity of the piston can be a very....
good thing or bad with regards to
performance. It is therefore worth a basic
understanding of what not to do even if you
only have a basic understanding..........
*Ok well remember when you were told that
higher compression was good? Well the truth
is that with high compression comes higher
dome temps/detonation and pre-ignition.
What you need is a good combination of squish
A)Squish: The area surrounding the combustion
chamber where things get rather close
between the head and piston.
* Ok so why a squish area?...Well there are a
few good resons.
1)move the mixture into the combustion
2)reduce the ability of flame spread onto
outside of the piston and reduce
* But alas with the squish doing a temp and
combustion control job there is the loss of
unburned potential power lost in the outside
charge that resists burning. Best settings for
(91-99) machines seems to be 7.5-7.9cc.
Squish should be set .026 to .028 of an inch.
B)Combustion Chamber: Yes its the area
surrounded by the squish band!!!! This pocket
does most of the real work and depending on
bike you own it could employ anything from
a hat-section,conical to a torus-type chamber
C)Plugs :Plug position in the combustion chamber
is also a very important item to monitor as
the goal again is not to screw with the
combustion. So you keep it as close to the roof
of the chamber as possible. The more it
protrudes the more inefficient the flame spread
across the pistons dome.
* Read plug for timming by the burn pattern on
the electrode tip. 3/4 to 7/8 from tip to plug will
be silver in color for correct ignition.
See tuning log for a useful item for reading plugs