1999 GP1200 Non-PV rebuild or New engine. HELP :(

If you sand off the sharp edges on the combustion chamber, the
damage will not cause a problem. But don't scratch or sand the
head gasket surface.

The crankcase is what worries me. Sometimes when a rod fails
it beats the cases outwards and lowers the center gasket surface.
If the center gasket surface has a dip, it is possible for the case
sealer to be ejected.

Most likely the piston fell apart, not the rod bearing. Should test
the cases on a flat plate (pane glass) with 220 or 320gr emery
cloth lightly glued with 3m spray 77.

Bill M.

That engine also had hard starting problems and sometimes a
damaged fuel pump check valve.

You need to perform 2 tests. (1) Test the centercase gasket surface.
(2) Pressure test the crankcase or just the center cylinder.

(1) To test test gasket surface, you need a flat surface, and glass may
be more continent than a granite block or a machined flat surface.
Try an Ace Hardware for a piece of 3/16" glass (thicker if possible,
it is good enough). Use a piece of shelving particle board as a base
for the glass. 3 pieces of 320gr emery cloth glued end to end ought
to be long enough. Use 3M spray 77. Spray a light coat on the sandpaper
and glass, then let it dry for a minute or two. Carefully lay the sandpaper
onto the glass. No overlapping edges.

Then tape or adhere the glass to the particle board.

Lightly sand each gasket surface. Use water to lube the sand paper.

You are looking for a low spot (that did not touch the sandpaper) on
the center cylinder.

(2) To pressure you either need to assemble the long block and block
off the carbs, exhaust, pulse line fittings. Or fabricate several block-off
plates from aluminum or plexiglass and 2 universal freeze plugs for the
crankshaft.

If you assemble the the engine, keep the pressure low ~10psi. If you are
testing the engine cases and maybe the cylinder and head, try more
pressure. The limit (if you have a good set-up) would be an air compressors
line pressure 10-0 to 125 psi.

Spray soapy water on the welded area to test for leaks.


Bill M.

Good Luck.