Crf 450,2004,cylinder marks???

[carl king 1986]

hi,just bought an 2004,crf 450,thought id strip her down do any bits to it that may need doing,after closer inspection of the cylinder i see this, is it anything bad? the bike ran fine had lots of power the only other thing i noticed was visible looking flame when you revved it hard!!!!!

 

[Rich Rohrich]

If you are referring to the cross-hatching marks in the cylinder then that is normal. If you can get access to a bore gauge then it would be worth measuring the bore taper, and piston to wall clearance. If not, the cylinder looks in pretty good shape from the pictures, so you can likely just scrub the bore using a maroon 7447 Scotchbrite pad with hot soapy water, and bolt it back together with a new piston, rings and wrist pin.