Michael-
You ask about boring your TR sleeves...
First of all, if you do bore your sleeves, make sure you have the pistons
first, so that the machinist can bore to the correct tolerances (more on this
later)
I know that they can be bored as I have lots of hearsay evidence
that supports this. However, I have never been able to have this done to my
expectations. Most automotive machine shops are just not set up with any way
to hold the cylinder without distorting it.
The best luck I have had is with a motorcycle machine shop, as they are used
to boring loose cylinders. Unfortunately, most motorcycle cylinders have some
sort of fin structure that is not concentric with the bore centerline. Most
of the boring machines use the top and bottom of the bore to clamp and hold
the cylinders,
but they also tend to use the fin structure ,usually an actual bolt hole or
at least a cut out for a bolt, to keep the cylinder from rotating in the jig.
This is where the TR cylinder sometimes gets out of alignment with the
centerline of the cylinder and the boring bar, resulting in an offset/oval
hole bored into the cylinder.
If you find someone who you feel can handle this operation, use the larger 86
or 87 mm cylinders so that the machinist doesn't have to bore so much out of
the cylinder. (A- the machinist will hate you, and B-it lessens the chance of
misalignment)
If you do end up using a motorcycle machinist, supply the exact
piston/cylinder clearances you desire as aircooled motorcycles run a much
wider clearance here and if the machinist bores to a wide clearance, you will
end up with a sloppy (worn out ?) piston to cylinder clearance.
The Car Curmudgeon
Nick in Nor Cal
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