Hi all, im new to this forum, been into bikes all my life, nearly 50 now, a lady friend of mine has a problem with her 81 xv750,it aint getting oil up to the cams, ive took oil pump off and screen was solid with crap, not took oil filter off yet, thought id ask first, could it be the pressure relief valve stuck? do you have to split cases to get at it? help? anybody? best regards Paul.

Cleaning all the crap off the oil strainer will probably restore oil pressure to the engine. If it cant suck enough it can't develop any pressure. A change of oil and a new filter will also help. Oh! and welcome to the forum.

Cleaned all the crap off strainer, new oil in, still no oil going up to the cams, is it possible the relief valve has stuck open? and is it a full strip to get to it?

It is possible for some crap to be stuck under the relief valve. I have seen it in the past on other machines but it's not common. I am not familiar with this bike so can't help with the mechanics. The only thing I can suggest is, if there is any external oil pipes. Take off one end and see if any oil comes out. You should see by just cranking it on the starter. Seems like a session with the workshop manual is in order. Good luck with it.

Not familiar with the XV, but i wouls suggest draining the oil (i know you put new in, but you can save it for later..) fill with flushing oil, let it run for a short while to get hot and loosen any crap/sludge, drain it and refill with the saved new oil, then test it again. And as Wrinkly said, if there are any external oil pipes check the oil flow from them while cranking.
It is possible for the relief valve to stick if there was a lot of crud in the original oil, also the by-pass valve for the oil filter, which would allow unfiltered oil to lubricate the engine components, generally a good flush out,new oil and filter would rectify these problems.
If there was sufficient oil flow/pressure after this and still no oil feed to the camshaft, i would suspect some kind of blockage in the oil line/gallery to the camshaft.
Is there anywhere you could attatch a pressure gauge to the oil system to check the pressure the pump can produce?