I'm trying to sort out a stumbling problem at 1/8 throttle 4500-4800 RPM.
I've only had this bike for a few weeks but it came with this problem new.
To make matters worse I've changed the exhaust. A little background info.
Stock the bikes starts with a FCR MX 41, 172 high sp jet, 50 low sp jet,
200 main air jet, 100 low air jet and a OBDVR needle 4th slot.
I have changed to a Leo Vince full exhaust, 178 high sp jet, 52 low sp jet
and swapped out the low air jet to a adjustable screw. I've made several other changes but it runs the best here. I had some testing done on a dyno
last week and the results showed the mixture to be very good everywhere
except when holding a constant 4500 RPM. At that point the mixture goes
very lean. If I roll the throttle up slowly I go right thru it and don't notice
a thing. But hold the throttle constant and it goes lean. My guess is the transition from the slow speed circuit onto the needle is the problem.
Does this make any sense. If so what needle's should I try?
Any help would be greatly appreciated.