CB175 Oil filter (cap removal)....

[Isleofmanfan]

With reference to item number 9 in this illustration...

http://www.cmsnl.com/honda-cb175-super-sport-175-k6-england_model16498/partslist/E09.html#results

When you have removed the M6 screw from the center, and you are struggling to (as the manual states, pull out the cap....where the M6 screw is removed from there is an M8 thread allowing you to GENTLY screw in an M8 bolt which will act as a puller and release the cap,