Wristpin

That was a Hayter accessory. For the 21 and Osprey. The machine's clutch had to be set up spot on. Back in the 80s we had a customer with two "tin legs" who lived out in the back woods about half a mile from his local pub and used to use his 21 and seat to get there! https://www.dropbox.com/s/t5neixtzozr80px/Hayter%20trailer%20seat0001.pdf?dl=0

If, when you bought it there was oil in the sump I think that it unlikely that either the main or big end bearings are the culprit - unless , of course the engine had seized in use . As you have suspected, the steel / cast iron rings have most likely seized to the bores/ liners. Can you drop the sump and slacken off all the bearing caps and see if there is any "rock" on the crank?

The situation is not totally clear. The gearboxes on early machines were filled with SAE90 oil (not EP) and could be topped up. There was then a switch to "sealed for life boxes" which were non serviceable. You will see that the "sealed for life" service bulletin refers to the Hayter 21 . I'm guessing that either the same applied to the Osprey. The attached is an extract from an Owners Instruction and Spare Parts Book covering Ospreys from serial 61/5771 upwards and a 1969 service bulletin which only refers to 21s.. Later books make no mention of the gearbox at all which is suggesting that no user maintenance was required. I would suggest that you remove whatever plug is fitted and if no lubricant is apparent make a bent wire dip stick and see if any is present. If none can be found it will be decision time! I would suggest (and it's only a suggestion!) a mix of SAE90 and Molyslip https://www.dropbox.com/s/5sjvlcenhz6ghfe/Hayter%2021%20%26%20Osprey%20Gearboxes0001.pdf?dl=0

When I first got involved with the mower business in the late 70s we had a machine in for service for which the only source of parts was John Harston . It wasn't a Pacemaker but at the moment the old brain isn't coming up with the name. In a previous life the Pacmaker name was on a three engined twin bowl motor scraper !

Reminds me of Cat Stevens's 1966 hit Matthew ans Sons. "the work's never done"!

Beats a lump of grease on the end of a screwdriver! Hazet tools are still in existence with a lot of special valve related tools for current vehicles but I can't see the collet tool in the on-line listings. I've never seen another in anyone's tool collection. I bought mine in the late 70s from a catalogue company called Gerald Staines of Ross on Wye who also did workshop assortment boxes , split pins etc under the brand name of Nubo .

Havn't got any collets handy but these give the general idea . Very useful when working within the confines of an L head valve chest.

There be one of they in my tool chest! Might even have the words Hazet 791 on it. Very useful for a fiddly job.

The angle grinder suggestion is very much s**t or b**t and should not be necessary. Not only that but welding it back up afterwards will probably shrink it and if done on the shaft make it as difficult to remove in the future and if done off the shaft it may require reaming to get it back on!

Would hate to see your vice damaged. If you have a sledge hammer it might be easier to hold that on one side while smiting the other side with the heaviest ball pein that you can muster. As far as heating goes, it will take a lot of BTUs to have any useful effect - more than the average "domestic" blow lamp and probably more than a normal workshop propane torch - it's oxy acetylene and red heat territory. Hayterettes with seized blade carrier discs were a case of remove the fuel tank, insert a sheet of steel and pile of soaking wet rags to protect the sump and bring the disc boss to red heat.

Give it the "stretching" treatment - it will give! If yours has the ball bearing crank on the PTO side, this is what you will find. https://www.dropbox.com/s/qsnl8etvvfo3g0g/Aspera%2CTec%20ball%20bearing%20PTO0001.pdf?dl=0

Your "bulky thing" , a sleeve or muff coupling may need a puller but if you have an anvil or well supported lump of steel and a lump hammer you can try shocking it to " stretch" it. Place the coupling square on the support and then smack it squarel with the hammer . Turn it through 90 degrees and repeat , then turn and repeat again. This may break any rust seal stretch it enough to release it.. When it is off, be aware that there is possibly a ball race retained with a circlip behind the oil seal , so pull the seal and have a look before struggling to remove the crankcase side cover.

Some Dellorto stuff https://www.dropbox.com/s/4e5bvilavixv3iv/Dellorto0001.pdf?dl=0 Emulsion tube removal

The Dellorto is pretty simple and much like any other small float bowl carb, throttle spindles wear and admit air, float needles wear as do the float pivot bars. The last two can be compensated for by a bit of judicious tweaking! Carb bowl O rings can still be found and complete carb sets can still be had from the UK Dellorto agent, Eurocarb. Removing the main jet ( emulsion tube) requires a hollow ground parallel sided screw driver to avoid terminal damage to the slot in the jet and subsequent need to drill it out and search for a replacement - you've been warned!!

They were fine, just a bit less tolerant of finger blight than Briggs!

Tread wear !

Had a blow out in road works on the M5 18 month ago but fortunately had a space saver spare but with no hard shoulder finding somewhere to fit it was a bit hairy. Now the current car has no spare, just gunk and a pump - madness. Quoted over £200 for a space saver and no well to put it in!

Looks the same as the Sealey one and at a great price. I've made several mods to mine, extra internal light, dust extraction for better visibility, finer mesh floor to prevent small parts falling through or getting tangled, lengthening the pickup hose and anchoring the pickup better. On the minus side the blasting medium does not flow to the pickup and every so often one has to tip the cabinet to get it to where it's needed It makes the compressor work quite hard but with glass bead blasting medium it is excellent for carburettors and starter housings etc. Not tried it with any more aggressive blasting material.

Certainly most Asperas of a certain age will repay a proper valve job - refaced valves and skimmed seats, BUT be careful to have the cam correctly positioned when checking / setting the valve clearances . The piston needs to be a quarter of an inch down the bore on the power stroke. Get it wrong and gap the valve when it is still on the decompressor and it will BITE!!

Should be 200mm diameter and OK for your job but there have been several changes of part number and the trail is a bit obscure! I believe that the original wheels for Ospreys and 21s of your era would have had three piece bearings - cup, race and cone - but the current ones have encapsulated bearings.

Point of order! ATCO (The Atlas Chain Company) did not originate in Stowmarket which was the home of the Suffolk Iron Foundry, but in Birmingham !

It wasn't so much the carb itself that was the issue but the lack of support in the way it was mounted leading to warped manifold flanges and air leaks etc. The Asperas of the day, had a reputation for poor starting but it was nearly always down to a combination of air leaks and lack of valve maintenance. Correctly maintained they were fine and the vertical shaft models had pressure lubrication while Briggs continued with splash for years. As far as I can see, the unusual air cleaner was the standard one for the day - an oval tin can with a sponge in it; a similar one, turned through ninety degrees was used on all the early two stroke Flymos. Now Stephan will tell us that it's a Clinton!

Looks like I'm in the minority but I thought Aspera / Tecumseh.

Chances are that all you will need is a diaphragm , BS 270026 from memory!

Conyers alternator coupled to a ten horsepower Tecumseh . Gen set assembled by the old Godfreys of Brenchley (Kent) company in the late 70s just before they went into liquidation - allegedly due to an ill advised venture into genset production involving Nigeria! This one is for sale. PM me if interested.