Hayter 21 project

[past-timer]

Hello people.
A first poster here.
I took a punt on a spares/repair 1975 Hayter 21 with B & S 5hp engine, a couple of months ago, and have the time now to give it some attention and hopefully get up and running to cut the grass on a small holding I own.
The good points are that the machine is complete and although it looks well used, the overall condition is pretty good for the age. The fuel tank is very clean, and the spark plug was a bit cokey but the important bit was biscuity, so I am pleased with that. The engine turns over on the pull cord and the piston is moving freely, and the clutch and clutch cable work. Most bolt heads/nuts are OK and not rounded/chewed.

The bad bits: Compression feels low, and looking down the spark plug hole, it looks like the visible valve is stuck closed. There is no spark. One of the four knives is broken, and all are seized.

I am planning to replace all the knives, overhaul the carb and if I have to replace the coil/ do whatever to get a spark.

Can anyone make any suggestions on how to sort the stuck valve. I could take the engine off and fully overhaul, but if I could find a shortcut for now, that would be very helpful. I’m guessing the machine was running but hopefully stopped being used when the knife sheared, and it has then sat for years and the valve has stuck.

thanks
Matt

[andyfrost]

Valves usually stick “open” , check again , as you say it appears to turn over OK , in which case the valve should at least be seen moving.

Andy.

[past-timer]

Thanks for response Andy. So with a squirt of some penetrating oil, a good torch and more perseverance, I’m very happy to say both valves are in fact moving. I put a compression gauge on the engine and after a few pulls can get to 80 psi. So a much better starting point.
I’ll try to get a spark, check the coil, and if necessary pull the fly wheel to check the points, service the carburettor and see how I go.
Matt

[andyfrost]

That’s a good start , next thing is remove flywheel , THOROUGHLY clean and reset points , and you should have a spark.Clean out Carb and tank , and most importantly fit new diaphragm.

Andy.

[past-timer]

So I fitted new points and condenser (I did eventually buy the funky little tool to compress the spring as I found that a bit of a fiddle without, and the wire from the coil is getting shorter where the spring cuts into it), I changed the carb diaphragm and put in a new plug, and bought a new air filter as the old one had disintegrated, and then this evening I put in fresh oil, and gave it a few pulls, and the engine started and ran smoothly. I’m delighted.
Next I need to replace the cutting knives, and tension the drive belt. The front wheels are very wobbly and I should be changing them, or hopefully just their bearings if I can do that.

[past-timer]

Can anyone advise on replacing the blades – I’ve got a new set. If I snug the bolt for each blade down, the knives will not rotate due to the aluminium plate not being flat. So I guess I need to fettle/flatten the dish locally so the knives do rotate when the bolts are tight – is that right?
Thanks

[john-e-w]

Try spacing with a washer
John E-W

[past-timer]

OK thanks will give it a go

[charlie]

A photo of the blade set up would help to see if aluminium plate should be flat and if blades should rotate.

[past-timer]

Thanks for your attention. Photos attached. All the blades swing from side to side, but they all foul on the plate because it is not flat, and so will not swing 360′. I wonder if I am overthinking this, and just a bit of deflection is all that is needed.

I checked the gearbox this morning, and it is good for oil.

I went to tension the drive belt, and realised I need to weld up one side of the tensioner as at the moment one side is not welded/broken, and therefore the tensioner is twisting the frame. This looks to have been a long time problem that was ignored in the past.

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[davidbliss]

When we had one never gave it a thought and fitted the free swinging blades the other way up so like all rotary mowers.

[past-timer]

Doh! thanks

[charlie]

The blades do not need to swing 360 on their mounting bolts, they only beed to swing in if an obstruction is hit. I suspect the bolts have a shoulder rather than a plain shank, to ensure the blades do swing.

[andyfrost]

It’s quite a common problem with the 21/Osprey models , having the Duralinium disc , they tended to “bend a small set” where the blades bolt on (see pic 2) , take the carrier off and simply hammer back into shape using a suitable anvil/block, in other words until perfectly flat , the blades should rotate freely through 369 degrees.When these blades were used on the smaller Hayterettes , it was not so much a problem as they used steel discs.

Andy.

[past-timer]

Thanks for this – I’ll give the plate a fettle at the weekend. I have now welded up the front frame tensioning plate, and I have also found some nos bearings for the front wheels which were in a right state/ missing. The rear height adjusting wing nut and collar are missing, so I’ve bored out a hex nut to slip over the 1/2 adjusting screw stud and intend to drill it for a Clevis pin to hold it in place.

All being well I’ll get some grass cut over Easter.

[Author]

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