OK, the NX is not the Ark and we just had a Memorial Day extended weekend that started off damp, got really soggy and then turned into a sweat box. The sweat box continues today and we've already had the obligatory Midwest afternoon thunderstorm (due to hot/humid conditions). This is not 'the epiphany' I had on the ride in this morning.
This is 'the epiphany': Suppose there isn't anything wrong with the NX. Read that once more; there isn't anything wrong with the NX. Why? Well, let's examine the steps taken to figure out what the issue might be; 1) assume it's the carb and remove/disassemble/reassemble/install ad nauseum. Result? No change in performance. 2) Check electronics for possible failure/failing. Result? All components within spec (per Honda shop manual). 3) Maintenance items; check for clogged air filter, check for clogged intake, check carb (see above), check for clogged exhaust. Result? No issues found. 4)Check cam and ignition timing. Result? All within spec (per Honda shop manual). Not much left to check, is there?
Recall that I traded emails with CPW (Carb Parts Warehouse) and their initial reaction was to "bump up the main 2 or 3 sizes". Also, I discovered that by applying partial choke the motor ran better in cold/cool weather. So, isn't it logical to think that the 125cc motor sheds heat so quickly that is never reaches proper operating temperature especially when the ambient temperature is below 45º F? Wasn't my last mpg reading 92? At this point I'm beginning to think that the carburetor is jetted too lean and that I need a richer main jet. I have a #105 (which is one or two steps richer). It wouldn't be hard to procure a #108 & #110 or a #110 and #115. I'm not sure if a "step" is 2.5 or 5 (my old DR350SE took "steps" in 2.5 increments). It shouldn't be hard to find out, though.
How did I discover this? I took a quick ride to "homeowner hell" (home improvement store) Saturday morning. It was in the low 70s and the bike did it's usual hesitation thing until it reached operating temperature and then it ran like gang-busters. I guess it finally dawned on me that I had a simple issue of a lean condition yet I was determined to find something else wrong. I need to check the plug when I get home to see what color the ignition tip is. That's a pretty good indicator of the air/fuel mixture.
Oil Change: I mentioned that the NX needed an oil change and I completed that a couple of weekends ago. The oil looked good, pretty clean and I didn't find anything 'bad' in the screen (no filter on the NX), like metal chips. I did find some type of "snot" lodged in the screen though. It came off with a shot of carburetor cleaner but I'm unsure of what it actually was. It was the same color as the oil but thick enough not to be able to pass thru the screen.