classic motorcycle forum

Alloy I think, judging by the look of the corrosion. I use a stone lubricated with kerosene (paraffin I think you call it) on cast iron pistons, but only ever a new file on an alloy piston. A used file often has shards of steel that can end up embedded in the soft piston.

R gives excellent advice. Can I add a warning? There is a mistake that many of us have made once - once is enough - that should be avoided at all costs.

With a one-piece cylinder and head be extremely careful if you put the loose piston and rings inside the cylinder. Do not push the piston up to the top! If the rings go over the top of the bore they will pop out into the combustion chamber, and getting the whole thing out again is extremely difficult. It's one of those "oh no" moments.

Have fun.

Leon

Yes you have to be cautious using emery cloth ANYWHERE inside an engine or on components,
the particles can remain, and turn into grinding paste !

The corrosion on the side of the piston if machined off would cause the piston
to have more clearance and thus piston slap - but won't affect compression.
I use a well blunted stainless steel wool - give all your saucepans a good clean with it first,
to blunt all the sharp edges. Polish in small circles, so you don't wear grooves in any particular direction.
Watch that it doesn't produce any visible scratches, in which case its not blunt enough.

The carbon on the top of the piston can mostly be scraped off using a blunt instrument - I mostly use a
sharpened wooden stick !  The aforementioned stainless steel wool also works well here.
Again watch that there are no scratches -  the piston top is not really a working surface,
although the finish is often less than pristine from previous owners attempts !
Smoothing off any previous scratches is a good plan, you don't want lumps or bumps becoming hot spots,
and possibly causing pre-ignition.


And the reason I mention STAINLESS steel wool is that ordinary stuff leaves tiny bits of steel wool everywhere,
which soon rust if exposed to dampness anytime - the last thing you want inside engines. (or outside for that matter).
Stainless wool  mostly breaks into long strands, which are easy to spot - and obviously kept away from inside engines.
have fun !

Hi

I had couple of interested persons from Saudi Arabia, India and South Africa, but decided not to ship to those destinations. Mentioned countries are unstable and bike could be stolen during transport.

Have this adjuster, but forgotten to install

Will ask Honda Museum, thank you for the advice.

Nice resort doco, thanks !