What size spark plug for a poulan pro 550 model

Here is b&s 800number have make ,model,serial number handy 800 444 7774

Take the spark plug out of the mower and look on the side of the plug and it will tell you which plug is needed to replace it with.

It depends on the model number for your saw.
Please re-post with you model number so that I, or others, May further help you.

Gap at 0.030

you need to unplug the spark plug then turn the mower on its side sounds like you hit a rock and bent something and if you bent the crank the belt might have fallen off

Go by the numbers on the original plug. The gap should always be set at 0.30.

There is no drain plug on that model , one has to lift up the entire machine ,tilt and drain the oil out of the filler spout. Change plug once a year - Champion# J19LM

Poulon 550 yellow 22" Briggs and Stratton. It looks like you have to drain it out the cap by tipping it. There IS no plug on mine - spent 40 minutes looking for one, and I know what both types of the plug look like. What a lousy design. This mower is a piece of junk. The valve froze a week after I got it. Never again. A headache.

under the deck above the blade. It is probably a square head pipe plug

Check air filter, replace if needed.
Check engine oil level and condition. Add/change as needed.
Check spark plug. Clean and re-gap if needed (.030 gap)
Drain the fuel and replace with fresh premium grade gasoline. If your local station has a notice on the pump regarding Ethanol content, drive to another station!

Most owner's manuals specify 89 octane or higher and most warranties become void if E85 fuel is used.

And finally, Oxygenated fuels are not your mower's best friend. :-)

Hope this helps.