Epiphany of sorts (??)

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.

MPG says you've lost your mind

So, I'm not happy with the way the NX has been running. I've chased fuel gremlins. I've checked for electrical issues. Nothing indicates that there's anything wrong except the hesitation that rears its head from time to time. Lately, the motor's been running pretty well. The latest indicator, how well it's running, is fuel economy. The last fill up was 1.518 gallons that covered 139.8 miles. You do the math; (fine, I'll do it for you) that's 92 miles per gallon. This is what I was expecting in the first place. How is it that a problem slowly fades and performance increases with use? I know it's not good when machines sit unused. This is certainly true of the NX. There's no other explanation for a bike, that's twenty-three years old, has just over two thousand miles on it. That would indicate, to me, LOTS of idle time. Doing the math shows about 89 miles per year, on average. Another thing, that occurred to me, is break in time. This motor had only one hundred miles on it since being rebuilt. Perhaps the rings are just starting to seat properly? I'd really like to know what a leak-down (compression) test would reveal. Finding the correct adapter, for my compression tester, would be great help. I'm now approaching one thousand miles on the rebuild and I'm thinking it's time for an oil change. Fortunately, I have Honda oil and don't need a filter (the NX has a screen). The weather is supposed to steadily improve for the next four or five days. Perhaps more sunshine and warm temps will prod the NX to continue to run well.

Look Elsewhere

I had been kicking around the idea of contacting Sudco, in southern California, for a few weeks now. I finally had an opportunity and chatted with Josh. In his opinion, the issues are not carburetor related (an interesting thought, I must say). In his opinion, I should start checking electrical things (wires, coils, regulators/rectifiers and connectors). What fun. As anyone who has ever tried to chase an electrical issue knows, problems like these can be total ghosts. They can also be expensive because replacing parts that are not bad is not cheap (especially when it comes to electrics). Another tip he had is to note the throttle position (on the hand grip). I've already noted that if/when the hesitation occurs, it's in the upper rev ranges (6500+ rpm). But, this morning the NX ran flawlessly. So, perhaps it is time to dig out the shop manual and review the procedure for checking electrical components. Also, I may need to strip off the body work and check/clean all electrical connections. Perhaps it might even be something simple.....

I also have another contact; Classic Honda Performance in Texas. Supposedly the owner, Lyle, knows a little something about NX125s. He's in Vegas this weekend but will be back in the shop next week.