Sharing my experience here changing the air and fuel filter and inspecting the spark plugs. Refer to the manual for the basics, but here are things that may help, along with some very surprising discoveries I made... 1) Removing the tank There are three things to disconnect besides the bolt...
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and someone else asked if I'd cut it open. Well, OK, I did it this time at 20K. Here's what I found....
I assume the filter was either white or yellow when it was a virgin. With very, very, rare exception I run only "first tier" gasoline, with Shell Premium as my first choice. So, I'd say, do whatever you think it best...