Rayp

The 46th annual Show returns to South Cerney Airfield Cirencester from August 3rd to 5th.  The Show is regarded as one of the biggest and best steam, vintage and countryside events in the UK.
Set in the former wartime airfield the sprawling show site covers around 2oo acres .  This year the Show features nearly 1,000 classic cars from pre and post-war eras including more than 70 classic American cars, 30 vintage car clubs, 335 motorcycles and scooters, 80 bicycles from 1903 to 1980, 30 miniature steam engines, 70 full-size steam engines, model engineering, 200 tractors, over 70 buses and coaches, 130 military vehicles, 315 emergency and commercial vehicles, 70 industrial trucks, 50 vintage caravans, over 50 model aircraft taking to the sky above, 180 trade stands and loads more  livestock and show arenas etc..

Its not very often you can say the earth shook when you're retired!

It's a bodge Ray. Have a look through this Thread for pics of what it should look like OSPREY. 
I've sent you a copy of the Manual which should cover it (via PM)
As for the link in the chain, I think I see it arrowed here -

 
Open end is usually on the trailing side of rotation .
You'll probably need to obtain and bond new friction pads onto the Toothed Clutch Plate. 
A link to the people I've used in the past if it helps-    Friction .
 
Bonding them well requires scrupulous cleaning and a good bonding resin like Araldite Original ( NOT the 5 min stuff).
I'm sure Wristpin, Nigel and others will offer more experienced options and advice on that and the machine.
Edit in RED

Setting up those clutches is a bit of a black art. In the 80s the roving Hayter Service man used to have an Osprey / 21 axle assembly set up on the bench in his high top van and ran an impromptu service course on site.
There should be a thick friction lining bonded to the large sprocket. I believe these are still available from an aftermarket supplier of friction materials.
However, from your image, it appears that there is a lot more to be done. Looking at the relationship between the bush and the axle it appears that one or the other - or both, are badly worn. I think that a complete strip and assessment of the axle is required.
 
https://www.dropbox.com/s/i5ys5rh1mdtrwc4/Hayter 21%2C Ospey Clutch adjustment0001.pdf?dl=0
 
https://www.dropbox.com/s/a2gbo2quuaymiea/Hayter Osprey and 21 0001.pdf?dl=0

Its not very often you can say the earth shook when you're retired!

Its not very often you can say the earth shook when you're retired!

Excellent work as usual Richard.  Its made me think what I can use my similar sliding lid winebox for!

Sorry Ray, I may have misunderstood. I didn't know you had ordered a Screw/Bolt for the Arm/Clamp, thought you were looking for one.
Just needed clarity on the Clamp width, as I suspected yours was horizontal shaft engine.
As for the measurement,  0.312" is near as damn it 5/16" (0.3125"), so it depends if your dial shows in 0.0005" graduations, but as you've ordered one, I'll cancel the search.
Regards.
 

Only five balls.
FG Adamsons are showing one 691630 in stock. They have both a retail and trade site. 
 
Edit. Should make it clear, 5 on the early single pawl starter and 6 for the later “ sealed” starter with 5 pawls.

In checking the clutch do inspect the backside of the hub where the sprocket is as well. A worn sprocket will allow the chain to slip and hinder performance.

Hi Richard - It looks really well made and I'm sure it will be better than new when you've worked your magic.

I wish I had known earlier - I've recently bought a second hand one from the USA!

Hello Ray, I have to  keep searching for your Tractor Model, as they are not all the same system of Battery layout/restraint. I presume the image below is like your machine?.
 

 
Easy enough to fabricate to actual spec if you note the spacing and diameter of the holes in the Tray. if the rods and hole dia is a 1/4", I can produce a set if you're desperate.
I would just need to know what your Battery type/height is , if you have now sorted which one you need.       

Most people take the battery hold downs off the first time they change the battery (often buying one the wrong size to save money), and discard the parts. This also happens with shields, cover plates and even air cleaners/filters at times. Its the disease of laziness when a person thinks no one will see them not completing the job correctly. 

If you mean the type that are a bit smaller that car ones, you can get them over here from places like Halfords and garden machinery dealers. I got some off a stall at one of the shows.

Thanks again Richard

Hi Ray.  0.020" is(was) the generic Points Gap of all old B&S Models...at least up to 1982 (as far as my Manual goes). What they did after that, I cannot say.
Also, if you need to know, the Plug Gap was always 0.030". 
Regards.

Hello Ray, Flywheel end is stated as the Front, choose your Engine and Type from the images below-

Prompted by Richard's excellent posting I thought I would post the work on my deck.  After sandblasting/wire-brushing and welding repairs the top was zinc-primed. The underside was Metal-prepped
then treated with two coats of POR.  I was unable to source small quantities of stainless steel flange bolts so purchased the nearest metric equivalent.  This meant the spacers required drilling-out, but when I tried the first one shattered. A friend then kindly made me some metric replacement spacers. All the remaining bolts were replaced with stainless steel and a new Bar Idler Bushing Spacer fitted.  I'm afraid I'll never achieve Richard's high standard, but I'm confident that the Deck will not corrode before me.
  

Prompted by Richard's excellent posting I thought I would post the work on my deck.  After sandblasting/wire-brushing and welding repairs the top was zinc-primed. The underside was Metal-prepped
then treated with two coats of POR.  I was unable to source small quantities of stainless steel flange bolts so purchased the nearest metric equivalent.  This meant the spacers required drilling-out, but when I tried the first one shattered. A friend then kindly made me some metric replacement spacers. All the remaining bolts were replaced with stainless steel and a new Bar Idler Bushing Spacer fitted.  I'm afraid I'll never achieve Richard's high standard, but I'm confident that the Deck will not corrode before me.
  

Just to let you know I followed all your advice regrinding both valves, decoking the head, replacing the plug, diaphragm and gaskets. The mower now starts easily and as soon as the new belt and blades arrive I hope to put it to work.

Just to let you know I followed all your advice regrinding both valves, decoking the head, replacing the plug, diaphragm and gaskets. The mower now starts easily and as soon as the new belt and blades arrive I hope to put it to work.

Just to let you know I followed all your advice regrinding both valves, decoking the head, replacing the plug, diaphragm and gaskets. The mower now starts easily and as soon as the new belt and blades arrive I hope to put it to work.

A trick I use, but can only be applied to OHV engines after valves have been lapped in and re-assembled, is  to pour petrol down the ports. If any dampness appears then I re-do them. If petrol can't get through, neither will gases.

Standard old school practice but not with petrol  - elf and safety. Paraffin , diesel or even water, but if valves are correctly lapped they will seal correctly. Only ever use the paste from the fine end of the tin; if that is not sufficient they need to be refaced and the seats cut. If the coarse paste is needed to recover a bad valve or seat the chances are that you will end up with a convex valve face and cupped seat. 
The days when cars needed a decoke every ten thousand miles and every village garage had refacing and seat cutting facilities are gone - as are the garages: so us small engine types have to seek out those who have the kit. A decent garden machinery workshop should have it as will vintage motor bike shops but otherwise it will be engine reconditoners who may turn up their noses at our sort of kit.