Villiers four stroke on Allen Scythe

Hi everyone, I'm new to the group and seeking suggestions. I bought a non-working Allen scythe last year and have begun trying to get it running to work, rather than enjoy an elegant retirement. I have stripped and freed the cutter bar, inspected the oscillating drive mechanism but have found the engine is solid due to the piston being seized in the cylinder. Also the exhaust valve has corroded off the end of its stem. These problems are due to it being left under a hedge for many years with the spark plug missing. The engine fan casing plate is almost unreadable but towards the top right hand side is a number 25T which I think must indicate it to be a mk 25 stationary engine mounted to the machine via a flange on the shaft outlet plate. Having been watching ebay for a while and not seeing anything on the lines of valves or pistons I chanced across this group and wondered if anyone has suggestions for (a) getting the piston out and (b) sourcing a valve?

John

Reply to
cynic
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Meetens do a lot of Villiers parts and could probably help. However, if it is that far gone, you'd probably be better off looking for a complete running MK25 (not uncommon) either on ebay or at the sales (Enstone coming up soon). You should then be able to swap any special bits (mountings, couplings etc) for the Allen Scythe application over to the 'new' engine and be up and running for probably less cost and less effort.

NHH

Reply to
NHH

That is a option depends "how far gone" it is. Taking the head off and looking at the damage is the next step I feel and possibly the sump/crank covers to see what it's like down there. If it doesn't look too bad, filling the pot with diesel and leaving it for a week, a few gentle taps onto a mandrel just slighly smaller than the bore, more diesel and waiting and repeating might free the piston. Removal of crank is probably adviseable so you know that the only thing stopping the piston moving is the corrsion between it and bore.

Reply to
Dave Liquorice

This link might be useful:

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Reply to
Richard H Huelin

Hmmm, have you got the head off yet? If so, what treatments have you tried? We can offer you all sorts of ideas once we know how far along you are!

Regards,

Kim Siddorn

Reply to
kimsiddorn

I tend to think that if it has got to the point of rusting the head off of the exhaust valve, then it is pretty far gone!

NHH

Reply to
NHH

I have removed the engine from the machine, taken the head off and poured light oil into the pot. When I started the piston was about

1/8" below the top of the cylinder. I have tapped the piston down using a steel pipe with a square end only a little less than the diameter of the bore and managed to move the piston down about an inch over a number of weeks resting and re-oiling by degrees. I have had the cylinder holding down nuts off and the crank rotates freely within the limits of piston movement and the cam followers move in synchronism with the crank while the cylinder block moves up and down. Basically the piston has reached a point where it is jammed where it is and I cant get to the underside to tap it back up again. Maybe the suggestion of simply swapping the whole engine is the best way forward in the circumstances. I am watching ebay and have seen a couple of other types of machinery with the same engine so if something goes for a low money bid I will follow that route and hopefully have the same shaft end to deal with. In the meantime I will keep applying penetrating oil and percussion.
Reply to
cynic

Try putting a couple of stout wooden blocks between the cylinder and crank case and see if the piston will continue its downward travel with a little further 'persuasion'.

NHH

Reply to
NHH

I can try that but I think the crank is at about 90 degrees from TDC at present so I wonder why it would make any diference?

Reply to
cynic

By judicious use of wooden blocks, you can move the piston further down the bore & eventually free it off. If it has moved this far, it will almost certainly go the rest of the way!

Heat the barrel with a gas torch too - every little helps.

Once off & the bore cleaned up with wet & dry, you might well be surprised to find how little corrosion has taken place. Heat cycling the piston will eventually free off the rings and away you go.

Regards,

Kim Siddorn

Reply to
kimsiddorn

I see, I thought you had run out of travel. Well, unless there is significant corrosion below the point at which the piston has stuck (unlikely), then it 'should' continue to move down with successive rounds of soaking and drifting.

NHH

Reply to
NHH

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