Today I completely removed the pv assembly and replaced the lot with new parts, the teeth on one of the pv's were worn slightly so I thought replacing them would solve the problem, but NO, when I fired it up it was exactly the same.
Although again, when I removed the left KIPS cover (or even just loosened it slightly to allow some air into the cylinder) it ran great!
It seems to help 100% by allowing air into the clylinder but I cant figure out why?
The reason why I am thinking of removing the valves is becuase when I got the bike it ran perfect, although after about 3 months the problem appeared. When I removed the head, I only found 1 pv installed so I am thinking that if I reinstall only 1 pv, then it may retun to the way it was
Long shot but if this doensnt sort it, then I think I am going to sell it on