Bolen 550 Series Small Push Mower

[DJR]

I have a 4 year-old mower that recently started running slow. I changed the spark plug at the end of the mowing season last year. This year, the mower was hard to start and when it did start it cut off after 30 minutes of mowing and would not restart. I have changed the oil, taken off the carburetor and cleaned it, cleaned to tank, put in new gas, and cleaned the air filter. The spark plug burned out again, so I replaced it again. Is the engine running to rich? How do I fix that? The mower still runs slow. Does anybody have an suggestions?

 

[ILENGINE]

Without the model number I am just guessing. Does this engine have the carb mounted on top of the tank. If so then the carb is notorious for warping below the carb pipe where it attaches the engine, and sucks the diaphragm in, and fuel gets sucked around it. Will need to replace the diaphram or possibly the carb. the other thing is some of these engines are mounted where the tab that the governor spring is attached gets bent when people mow under bushes etc, causing slow engine speeds.

just a couple things to check anyway.