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.

Sundry items

While that sat soaking, start to clean up the pressed steel mag and cylinder covers. Theyre covered in surface rust but solid, also covered in gunge & tar type stuff.
The rest of the scooter is sat there with the rear wheel propping up the back, - so it still looks like a complete scoot while I work on the engine. Didnt want to strip it totally and end up with boxes and boxes of bits then lose enthusiasm - as it is now I can still sit on it and go 'brum brum'!

The plan is to get the engine done, in a frame and running before attacking the rest, maybe just take off things that leave it looking fairly complete, - petrol tank, mudguard etc. - and do it for as little cost as possible!

The siezed piston.....

On to the next problem, - the siezed piston.
I had taken the cylinder head off a while back and could see the piston head, looked in good condition, no scoring to side of cylinder, - might come out easily? - fat chance! Now with the mag flange off and access to the crankshaft, started tapping the crankshaft round with a bar in one of the crankshaft holes - it started to move, - got all excited, - until I realised the cylinder was moving off the casing with piston firmly stuck inside - der! Once cylinder had seperated by about an inch, put some wood inbetween and wacked top off piston with a large hammer on a piece of wood - after a while - nothing, its stuck fast.
Have a google search for inspiration, - cutting through the conrod is an option, but want to save as much as possible.
Have a plan, - over next couple of days cobble together a stand so that the cylinder is supported upright with engine swinging freely below, so that when I whack the piston theres no force on the engine.

above pic shows the completed stand - engine with cylinder head bolts/studs removed- an old steel framed stool with seat removed ( and placed underneath in case engine drops) and two pieces of square profile tubing (old table legs) kept together with a couple of bits of 6mm threaded bar with nuts/washers. Top up the cylinder with diesel and leave to soak for a week.

After a week give the cylinder a good going over with the blowtorch - get some wood and start hammering the piston head, - then start really hammering the piston head, -  the start really, really hammering the piston head, until Im surrounded by mounds of smashed wood, - cant see any discernable movement - but convince myself its moved at least a tenth of a millimeter. Clear up the carnage, top up with more diesel and leave for another week.

6 - Assault on the mag flange

Made a mag flange pulluing tool - happened to have a steel mounting pole used for projectors from ceilings - the base of which was ideal to cut off - a fair bit of sawing and drilling involved, finished off with a bit of welding to keep nut in place.
In it goes and fasten down the two 6mm bolts into the recommended threaded holes - start winding it up while tapping around the outside witha block of wood, - nothing - keep winding up - bang! one of the 6mm bolts has stripped, - bugger1 - and not a sign of any movement.
After a fair bit of cursing and swearing and wondering what to do now I come up with a cunning plan, - I rule out trying to retap the stripped 6mm as the flange seems that stuck it might just strip again - decide to try tapping out the three larger holes for inserting the stator plate fastening bolts. The problem is that the taps I have got start at a pointed end and wont start to cut a thread as theres only around 5/6mm thickness of flange and I dont want to ruin the threads on the casing side..  Plan B - ream out a shaving from end of the holes - place a 8mm bolt over the hole - and give it a good whack with a hammer - this causes it to get a bite into the alloy flange - then with brute force drive in the bolt to cut a thread as far down as the engine casing - works surprisingly well and do all three with relative ease, - nice!
This means drilling three appropriate holes in my tool (ow!) - duly done and insert the thing in to try. Start winding up, nothing - keep winding - getting bloody tight but still nothing, - use a bit of steel tube for more force - the steel late and tube on the tool starts to buckle and bend but still nothing, not half a millimetre of movement, - daren't wind up any more otherwise somethings going to break! - Give up for the day and retire to curse and have think.

Following day .......enter the garage with grim determination - that bloody mag flange is coming off today!
Start winding up the tool as far as I dare - there must be a huge pressure, just hoping the 8mm bolts will hold, - then get an old (well, it is now) kitchen bread knife with plain cutting edge and hammer it into the gasket between flange and casing hoping to break the seal or whatever, - keep at this for a while daring to have another quarter turn on the tool now and then - nothing! Getting pissed off now - grab a piece of 3x2 and use a hammer to knock around the edge of flange - eventually give it a few almighty wallops risking the casting - bloody hell - a very small gap has opened up!   Only just enough to get the knife in but its moved - wind up a little more, wont budge, - get a wide blade wood chisel and tap that in - more wallops with the 3x2 - hey, were up to about 2mm of seperation! - anyway - more wallops and keep winding up, it eventually comes out - fantastic, - chuck it on the bench - off for a well deseved beer or three!

Flange with home made tool in place, - the immense pressure has buckled the steel base and pulled in the sides of the steel tube and its pretty thick solid stuff, its as if the flange was glued in place. 2 of the 3 8mm bolts visible, - theres a nut on them to spin down onto the baseplate when theyve gone far enough in to reach the engine casing, - theres no way I would have got the flange off without this - I reckon even the official tool would have stripped the two 6mm bolts. What a b*st*rd that was!