Harrier 41 with Briggs and Stratton Quantum 650 engine. Carburettor query.

[Jimbo1]

Our ten year old Harrier 41 with a Briggs and Stratton Quantum 650 engine has all the signs of the carburettor 'running rich'.....The spark plug is black and sooty, the exhaust fumes smell sweet and the engine seems to be hunting or surging.  I have cleaned the jet in the float bowl of the carburettor but do not know if there are any other cleaning, maintenance or adjustments that I can carry out.  The Hayter Handbook says it's a 'Main Dealer' issue, and the Briggs and Stratton Manual refers to the need for it to be set up to comply with the correct emission standards.

Almost from new, the machine has been a reluctant starter when the engine is hot, but other than that it has been a good purchase, and it does have regular oil changes, plug cleaning, sharpening and all the other recommended maintenance.

I would be grateful for any guidance.

Kind regards
Jim

[Mick]

Hi Jim.  Would it be possible to see some photos of the actual carburettor that's fitted on your engine please.  Same engine can use various carbs so it would be handy.

Sounds like you have more of an issue with the pilot jet side of the carb, or an air leak.  These can suffer with worn o-rings between carb to inlet, especially if the carb mounting bracket is loose.  The inlet tube can also be loose on the engine block, or have a hole or a split in it, these are quite common issues.

The other thing you need to check is the float level, there's some info I posted here. Check your float level