Time for a clean up

All work so far has resulted in getting covered in black oil and gunge, so have a good clean up with white spirit to get rid of as much as possible to enable working a bit cleaner.

 Inside the engine casing after a clean up.

 - and outside, - still a few bits hanging on - cleaning out the fins around the casting edges edges was a pain. Had to saw off one of the brake shoes as it was stuck fast.

Spent a bit more time on getting the front casing nice and clean as its the one you can see when its in the machine!
Kickstart assembly seems fine so leaving that in there for now.
Well, unbelievably, I'm almost in a position to start rebuilding and replacing a few bits - the downside of that is that Ill have to dust down the old wallet and go and spend some money - amongst other things ill need some bearings, clutch plates, piston & rings, probably a new chain if I cant reuse this one. etc.

Gearbox

-lets have a look at the gearbox - already had the end plate off and removed the bearing, which was knackered, - much play- probably got a hefty jolt every time it was put in gear with the long slack chain. Just loosely fastened the plate back on while doing other things.
Once the end plate is off everything just comes apart dead easy - place all my bits in order on a tray, - only the selector shaft to undo with a single bolt. mainshaft/layshaft comes out with a mild wallop with a piece of wood. Everything seems in good order, very little wear at all - all nicely reuseable - apparently a favourite spot for wear is in the sliding dog/layshaft cursor, on the square profile ends, - if these wear and get rounded off it can cause gear selection problems/jumping out etc - this is in really good nick.
Get out my gallon of white spirit to get everything de-gunged and cleaned up.

The contents of the gearbox - all cleaned up and laid out - not that much to it really when you get it all out - looks more frightening on the exploded diagram in the manual.
To far right is the bearing covering plate from the hub side, to access the bearing - might leave that in it seems in good condition, probably just replace the oil seal ( apart from that theyre quite expensive!).

Cylinder

The fins on the cylinder were absolutely stuffed full of thick muck & tarry gunge - the engine casing was also coveered in the same stuff. Horrible stuff to get off, like a mixture of thick tar and fine sand. The fins on the cylinder casting were filled up - cant have been much cooling due to airflow at all, possibly a contribution to the engine siezing up?

Been scraping bits off now and again over the past few weeks and its getting a bit cleaner. attacking the cylinder vanes/fins now with a small screwdriver and a kitchen knife, - its slow going.
Just hope its going to be fit to reuse when cleaned up.
Removed the crankshaft - covered in black gunge, - but seems alright - just a slight bend in the con rod, -in the vice and gave it a clout with the hammer - seems ok now!

The siezed piston attacked......

Well here we go again, its had a week of soaking in diesel and Ive made some short lengths of 2x2 timber, slightly rounded to fit in the cylinder and with a bit of tin plate screwed over the ends to prevent the wood splitting. - place in the wood after draining off the diesel and with the long handled lump hammer - whack! whack! and more whacks until the wood disintegrates! - not a sausage1 - repeat the procedure a few more times getting quite a sweat on - nothing - no sign of movement at all, - bollocks!
Ah well, nothing for it, - my long handled lump hammer has a hexagonal head which nicely fits in the cylinder, - pop it in and whack it with another lump hammer, - bang bang bang! - have a peek in, - the top of the piston is cracking but we have movement-hurrah - keep on whacking until the heads in up to the wooden hammer shaft, - the middle of the piston head has now broken completely off and dropped through, - fortunately have a bit of steel tube just big enough to make contacyt with outer edge of remaining piston, - in it goes and more and more whacking until, eventually, plop, the engine drops the remaining half inch onto the cushion, - time to survey the damage....

Well, the piston is well and truly knackered, - knock out the gudgeon pin/roller bearing, and extract the crankshaft, - that all appears ok. Inspect inside the cylinder, - doesnt seem to have cut any grooves out while on its way down, but there is some marking at the level where the piston was stuck. So, not sure at the moment whether I can re-use the cylinder, - might have to seek advice on that, but at least the bloody thing is out.