its about exhaust, and how you mount it
There is no standard way to mount the exhaust. Like many
other aspects of the conversion, pipe mounting is left up to
the creativity of the converter. If you look closely at the
SH pictures, you will notice a bracket welded on the subframe
that is there to mount the back bracket of the pipe. On a
stock CR250 frame, that bracket mounts on the the main frame.
Many try to locate the frame mounts etc., so that a stock pipe
can be used. That way you are not having to relocate the
pipe tabs everytime you need to replace it.
SH modifies the pipe and silencer to work on their application.
Since they have the volume, Pro Circuit and FMF fabricate pipes
and silencers to their specs. When you need a new one, you call
SH and they have it.
also curious about air box and filters
The airbox is another sub assembly that needs a lot of work to
fit especially when using a CRF frame. The problem is with the
distance and position of the carburetor on the 500 compared
to the thumper. SH is now using "X" subrames and airboxes
along with an adaptor plate mounted to the front of the airbox
to relocate the boot. There are as many ways to do this mod
as there are people doing it. The filter would be specific to
whatever airbox you choose to use.
parts, other than motor, would be specific to the year and model of the chassis, is this correct.
That's correct for the most part.
dogger