Mend Briggs & Stratton 35 Classic 3.5 Lawn Mowers

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Mend Briggs & Stratton 35 Classic 3.5 Hp

Lawn mower running rough?

Hello
I've had a Briggs and Stratton 35 Classic 3.5 hp for about 8 years and its been great until recently. Its running rough chugging and a little blue smoke. I hit a tree root a few weeks ago and its been like this ever since? I've took the spark plug out and it was black and a little wet cleaned it and cleaned the air filter ran it for about 20 seconds it still ran rough checked the plug and it was black again. Its like its running rich or not getting the air fuel mixture right or even out of timing?

Can anybody tell me how to put it right?

Dave.

David Roberts
June 2008

Briggs & Stratton Briggs & Stratton 35 Classic 3.5 Garden Tools, Lawn Mowers Briggs Stratton Hp

Diaphram sounds good to me, oiled up plug heavy fuel consumption blue smoke (chugging) diaphram deffo.

Alan B
July 2012

Probably the diaphragm in the carburretor- they need replacing every so often.

The Oracle
April 2009

Callum can you pls let us know how to change piston

jane
April 2009

I had a similar problem with my lawnmower (also 3.5hp B&S), which cleared itself up after using it for half an hour. What had happened was that the oil from the sump had gone into the carburettor or air filter, and was being fed in with the petrol. I'm betting you turned the machine over, or onto its side, to look at the damage.
In my case, I'd also put a bit too much oil into the sump, which didn't help.

Alvery
July 2008