Lawnmower misfiring

zilog_jones

I just acquired a second-hand lawn mower recently, and it hasn't been used in a few years. I put some fresh petrol in it and it starts up, but it's running very slowly and rough, and there's some smoke out of the exhaust.

I noticed the spark plug terminal was rusted up and the connector on the HT lead is even worse - could this be my problem? Is it easy enough to replace the lead?

I also noticed the foam air filter seems a bit oily/sticky - is this normal? Looks like it needs replacing anyway.

Any recommendations for getting parts in Cork or Limerick?

It's a Harry lawnmower with a Briggs & Stratton Classic 35 motor, made in 2002. I believe whoever made these have gone bust, so it would be hard to get any parts outside of the engine?

Thunderbird2

Is there oil in it

zilog_jones

Yes there's oil in it (sorry forgot to say), but I wouldn't be surprised if it's 10 year old oil at this stage.

zilog_jones

I went to Atkins in Cork today, got a new plug cap and service kit (plug, oil and filter) - hopefully this will sort it out...

paddy147

Check the spark plug and its gap too.

zilog_jones

I changed the plug and cap but it didn't really make any difference. The plug was black and oily - I guess that's expected when it was running like that. Maybe it wasn't actually misfiring.

I changed the oil (seems like there was too much in there, and it looked pretty bad), filter and cleaned out the carburettor and after that it's running well.

There seems to be a lot of vibration though - maybe I'm not used to petrol mowers but could the blade need balancing?

Oldtree

Might be worth spending the €40 on a professional service.

zilog_jones

I don't see why - I've already done most of the work.

I might take the blade somewhere to get it balanced/sharpened, but the vibration doesn't seem as bad any more so maybe it was just dirt somewhere...