Hi. Picked up a 1985 250 es big red. The issue: if i give it throttle too quickly, it will bog out. Bog out in my case is appears to lose fuel, and want to shut off. it actually will shut off if i hold the throttle open. if i immediately release it, and reapply the throttle slowly, i can “save it” from shutting off. i removed the carb and rebuilt it with a shindy kit. it was actually not that dirty. must of been cleaned by the previous owner. what i did notice, was the air screw was missing the washer, and the rubber o ring was crushed in between the spring....so i thought i def found the problem.. nope... problem still exists. i thought about the synchronization, but it looked good to me.. 2 turns out on the air screw. Original exhaust, and oem air box. new gas, plastic tank, new plug. I removed the exhaust clearing plate, pretty clean, not much carbon crud at all..just need some advice from the veterans as to where to turn next. plug inspection? valve clearance? ignition adjustment? never played with cdi system..Thanks in advance..
PS: i own a 70 that does the same and could never figure it out..currently down to the frame for overhaul..rings were shot and fouling plugs..