What part of Washington state? I am over here on the dry side just south of Pullman. I had not messed with slow jet at all since idle quality was good and the mixture screw was turned out about normal. But I was curious so I came down to the shop today and pulled out the slow jet to see what size it is. It is a 45, which got me wondering since everyone else is talking about 65's. I looked it up on Babbits online oem lookup and 45 is standard for 85-7 XR600 carbs. I even pulled the slow jet out of a spare set of xl carbs to look and it was 65. I do know that the needle and needle jets are different between the XR and XL, maybe that is worth pursuing? They are still available, I bought a set from Babbits. Occasionally XR carbs pop up on Ebay too. It has been my experience that fooling with slow jets doesn't do much. Anytime I have gone much bigger on a slow jet it is too rich to idle properly. I think slide cutaway and needles have much more effect on low end than pilot jets and my theory is that by speeding up the secondary carb you actually emulate a lower slide cutaway since the secondary has little or none and it is now coming on above idle. besides the secondary carb has no slow jet at all anyway so my speeding opening should have caused a horrible flat spot if it relied on slow speed circuit for initial enrichment. I wouldn't go much richer on the slow speed if I were you. Maybe a 65 but no more, if the idle mixture can be adjusted it is probably ok.