My 285 was hard to start when I bought it and improved with a new fuel filter. Then it got really hard to start again. After it finally starts and is warmed up, it can set for about an hour and still start on the first hit. Any longer and I have to crank and crank. I've cleaned the carb, twice. The second time because after the first time it was still hard to start and was pulsing and turning the mixture screw in has no effect on it. Turning it back out about 2 turns will smooth things out some, but it's still really hard to start when it's cold. I've soaked it Chemdip Carb Cleaner, 20 minutes (per directions on the can, first time. About 18 hours the second time and blew every orifice out with carb cleaner. I'm tempted to just get a new one.