I have a great 1975xs650b that runs great but rich- I've had the carbs off many times and tried lots of things. I thought the richness might be from needle jets that may have been internally corroded from years of varnish and non use. So I ordered the needle jets that Mike said are for my year. They said z-6 and I looked at mine and they also said z-6. I got them today and I opened the box and the parts are not the same! Here is what i got. My needle jet is on the far right and mikes are on the left. The funky thing is that they all say z-6. Going back on Mikes website it now looks like the z-8 looks like mine but my model calls for z-6's. I also messed up my carb gasket in the process. Should I just order the z-8s and hope they work? I just want to ride.