Sick Mountfeild HP474 Petrol Mower

[Craigdci]

Hi all

can anyone help, I have a Mountfeild hp474 petrol mower I bought this off a friend and after getting it home a noticed there was engine oil coming out of the filter, I had taken off the carb cleaned it all with new filter and plug and everything was good after then then over the past few weeks she has been running not right, fires up no problem runs fine at fool throttle/choke, once it has warmed up and oush the throttle to the rabbit it starts to hunt and struggle a bit, it can then start to do the odd misfire and when it does there is a puff of black smoke from the exhaust, it has a LHP16 carburettor and I have changed the oil, fresh fuel, spark plug(Briggs&Stratton) new gasket between carb and filter box, new filter and new rubber ring gasket. There is nothing more I can change and the carb is none adjustable. Can anyone shed any light on what it could be

Thanks

 

[Burnerman]

Have you dismantled the carb at all.....if you have, was there any debris or water in the float bowl?
John

 

[Craigdci]

Have you dismantled the carb at all.....if you have, was there any debris or water in the float bowl?
John

Hi, yeah had a look there was no dirt or debris, I have even sprayed carb cleaner in it and gave it a good clean but still the same

 

[Craigdci]

Just wondering if to buy a 2nd hand carb and try that

 

[Burnerman]

You can do, maybe GHS Ltd can do you a new pattern one for around £20?
I suspect there is some debris in the carb, possibly in the emulsion tube which lives above the main jet. No harm in having a bash to clean it, but you'll need an aerosol of carb cleaner on stand by.
If you carry on, mark the position of the float chamber to carb body before removing it.
John