Looks like that cylinder has ingested a few ball bearings!

Piston Removal
Using a very small set of fine Pliers, Circlip was removed on the one side.



Image taken from the later rebuild stage, apply a little heat to the Piston makes removing the, Gudgeon Pin/Wrist Pin/Piston Pin or whatever it’s called these days, somewhat a little easier.



Process was repeated on the other Piston.

Crankcase Additional Components Removal
Before removing the Bolts to split the Crankcase there are a few other items to remove as follows, however, before starting I found a bit of what looks like a piece of stretched Spring most probably from one of the Engine Seals. This didn’t look good and was most probably the start of the Engine demise and moon cratered Piston!




The Gear Position Sensor (GPS) was removed from the lower Crankcase and its cable routing noted (have to this these days as I have a memory like a sieve).
Testing the GPS it was found to be totally unserviceable; however, even if it was serviceable, it still wouldn’t have worked, but may have saved a few pennies later on (See Post 'Gearbox Cassette Removal' above), so a new GPS had to be obtained.
Note: JAUCE, WEBIKE, AMAZON JAPAN & WEMOTO supply these when in stock. It’s a pity you can’t get a new MC28 Neutral Switch as that is all that is needed for the MC18.




The Clutch Actuating Arm was removed as the Oil Seal needed replacing just to make sure. Some heat on the Bolt holding the Clutch Actuating Arm may be needed as the thread probably had some Locking Agent applied.

ericandchi wrote:Looks like that cylinder has ingested a few ball bearings!

Think this Image reveals all, total Carnage! Any views on why this happens?