I think this is your model, right?
https://www.championpowerequipment.com/search/200911
But there are 3 versions of it with different serial numbers. You'll see them at the link below. You'll want to know which one is yours. You didn't say whether you bought new or used. The number should be on the side of the block or alternator. Or if it's new, it should be right on the cover of your manual I think. It is on my Champion.
As for spare parts, I bought a spare carburetor and AVR module. I also got an air filter. If it's new I would replace the stock spark plug with the NGK equivalent. It should be listed in your manual. The stock plugs are ****. After that it depends on what you want to spend. Maybe brushes. I don't think they're too expensive.
I look at it as cheap insurance. It may be under warranty if it's new. Their tech people are usually very helpful if you have a problem. But if you're in the middle of a power outage you don't have a week for them to send parts to you. Just my two cents.
If you're just trying to buy spare parts I found emailing them is the best. Model number, serial number, and a list of parts you want. When I ordered parts a while back it was at a bad time. There had been hurricanes in Louisiana and Texas so they were swamped with emergencies, as probably all the generator companies were. So it took a couple tries. But their customer service is very good. I found them nice people to deal with.
