Wait for My67xr to verify, but I reckon if the case looks like the bottom one, there is no internal filter (Like MM mentioned above) The only one on that style YX that i'm aware of is the external one that should be on your external oil line like this
and what it looks llike inside
if thats the case pull it out and give it a good clean out with petrol (try no to get any on the rubber o-ring)
Hmmm, iv'e never looked in there before LOL got an oil change to do this weekend so if i get time i'll pull the side off and have a squiz. Bugger i though i might of finally got one up one you LOL.
i wouldn't think they they'd delete the bottom of the case filter screen in any of them ?
mainly due to it being the oil feed/pickup point for the oil pump in all the pit bike engines.
but i could be wrong too...
Yes yx 150's have that internal screen inside the case near the sump plug. They also have either an external or internal filter/ screen thats separate. So both Craig and Tim are correct. On my yx 150- ish my external filter is now the 160ho screen type, cause it's washable and reuse able.