254 suddenly running rich

[Tom D]

My ported 254 has suddenly stopped running, it starts and ticks over for a few seconds then dies, flooded. It's running too rich, the plug is black and oily. Looking for suggestions as to the culprit..

[lurkalot]

Welch plug fallen out in carb, (pretty common), metering needle sticking, or diaphragm(s) has a leak.  Could be any of those things to be honest.

[Khriss]

Def carb- diaphragms / dirt /   try a carb swap if possible ? K

[Tom D]

I have a spare saw so I might try the other carb. I also have an ultrasonic cleaner so I could give that a go..

[spudulike]

Make sure the air filter is clean, it may look clean but inspect the mesh with a magnifying glass as washing with warm water can block the open areas. Make sure the choke isn't flipping on somehow - can't see how it would on a 254 but check anyway. It is possible the H screw has wound out or other people with the latest machines are pissed at your ported 254 being faster and have sabotaged it.....who ported it

Other than that, perhaps a needle jet that has started leaking, dodgy diaphragm, leaking high speed check valve (very possible) or leaking welch plug. You will need to know your stuff on some of these carb issues!

Perhaps a carb kit and a US clean may sort it.