ellandoh,
I'm glad I took the time to read this thread ..I may have saved myself some extra $$$ that could be spent elsewhere.
I live here in very hot So Cal...in the low desert, always riding at sea level, up to about 1000 ft. in some of the Glamis dunes. I should note that in the summer heat, I only ride in the early morning or late evening maybe up to about 90 degs. max.
I just got my new to me '03 CR250. It has a Doma pipe, stock silencer, Twin Air filter, and V-Force V3 reeds. It was just recently re-jetted by the previous onwer, and to me it felt a bit rich when ridden. It had a 35 slow jet, a 400 MJ, and a 6BHY-38-71 neecle jet (2nd), and the AS out to about 2 1/4 turns. I found it to be pretty rich. The plug was new, but was wet black with a bit of soot...definately rich in my view! Oh the bike is currently running 40:1 Maxima 927 with pump gas.
So, I find your posting, and since your situation is about as close to mine as I have found...I'm going to follow your tips and see where I go...
I will first try going back to the factory's, and well as about everybody else I've ever spoken to, recommended 32:1 ratio. That, as I understand it will lean it out a bit. I will also be switching to KLOTZ R-50 pre-mix, based on both my adult son's great results on their current and past 2-strokes.
If that seems to help, but it still needs leaning, then I will go to the same settings you are using, and see from there. I have the stock 30 slow jet and 73 needle jet, and I also have 410 and 420 MJ's. When I go to San Diego on Wednesday, I'll stop at Bike Bandit and pick up a gasket kit, and a new 74 needle.
Thanks for providing your info, and I'll post my results as well...
Take Care,
JJ