When going to a larger 55mm tb you have to open
up the M1/2BBL or there will be a step going into the intake that
you see below.
To match the M1 to the tb remove the tb gasket
(above) and remount the tb to the M1. Make sure the tb is centered and
firmly in place, then open the butterflies and look inside. You will see a
lip where the tb meets the m1. Taking a fine tip Sharpe marker run it
across the top of the area's that are protruding out that need to be
removed. I pressed lightly the first time so it would take it part of the
way down. Remove the tb and then use masking tape to cover the holes for
mounting the tb to avoid filings filing them. I also covered the rest of
the M1 with a pair of shop rags to keep debris out of t the other holes.
With a cutting bit in the Dremel I removed all the material till the black
line on top was gone. Then I cleaned off the filings and reattached
it to see how much more it needed. Re-marked it with the Sharpe and
removed it and opened it up further and graduated the opening further into