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Collection, Preservation and Display of Old Lawn Mowers

Villiers mk 7-1

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I have a Ransomes Mercury mower fitted with a 4 stroke Villiers 7/1 engine, I have new s10 carburettor on the engine. The issue I have is the engine stalls when hot after about 30 minutes and will not start until it has cooled down. 

The spark plug was sooting up so I have weakened the mixture it does run better but still stalls. I am guessing this may be a problem with the coil?

Does anyone know if these engines have a condenser? Would it be more likely to be this that is the problem.

It is quite expensive to have the coil rewound so wanted to be sure about the problem before I invested the time and money.

Any experience of these engines would be great.

Forums

hortimech Fri, 28/06/2019

How does the engine stop ? Does it start to 'miss' and then stop ? or does it taper away to a stop ? or does it just stop without any of these things happening.

If it starts misfiring and stops, then yes, it could be the coil or the condensor (yes, it does have one), how ever it could be the points just want cleaning and regapping.

If it slows to a stop then it could be a fuel problem, check fuel tank cap etc

If it just stops, it could be something like the exhaust valve overheating and sticking in its guide and then releasing when it cools down.

It is a bit difficult to diagnose from a distance as it could be anything ;-)

Series3boy Mon, 01/07/2019

Thank you for your advice. It just stops with no misfire. I changed the petrol tap but for some reason there seems to be an air lock in the fuel line. I took the float cover off the carb and pushed the float down this pulled the fuel through. It mowed the lawn without stalling. 

I wondered if the float needle is sticking in the needle seat? Or could it due to an air leak around the Bangor fitting.