Tuesday, May 31, 2011

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.

Monday, May 23, 2011

Still there, lurking....

The local temperatures continue to climb and the NX continues its mysterious hesitation issue. Now, it almost seems as if it's temperature related. The starting procedure is pretty straight forward; turn the petcock to 'on', apply 1/2 choke, flip the ignition switch to "run", turn on the ignition (key) to 'on' and press the starter button. Usually the NX purrs to life and I allow it to warm up before setting off. Before I leave the driveway, I'm at 1/4 choke. Unfortunately, the first major thoroughfare I encounter has a speed limit of 45 mph (realistically, 50 mph). So, the NX has all of three blocks to get the oil warmed up (not going to happen). However, acceleration needs to be quick and the choke is off completely by the time I'm a few hundred yards down the major road. If I don't completely remove the choke, the motor will start to bog (running rich). Since the motor isn't up to temperature, there is usually some hesitation/stumbling. This is where I cannot tell if it's a carburetor issue, an electrical issue or engine-not-up-to-temp issue. If I'm lucky, the engine will be up to temperature within another mile and I'll know if the motor is "on song" or "off song". I'm supposing it's time to bite the bullet and try a new coil. I've noticed that the TTO Rev Counter (tachometer) jumps around quite a bit, I'm talking thousands of rpm, while the motor idles (either at start-up or while waiting for traffic signals). For instance, I noticed that the tach would register between 960 and 2800 rpm while I held a constant throttle during motor warm-up (first thing this morning). I have to believe there will be some delay with the read out due to the way the tach senses electrical pulses (induction). But, why would it jump all over like that? Perhaps it's time for a call into Trail Tech.

I did exchange one email with Classic Honda Performance in Texas. Lyle, the owner, suggested I try another coil but wasn't sure exactly what an NX125 was. He thought it was a scooter. When I replied with clarification and asked if he recommended one of his products (CHP makes a replacement coil that claims superiority over the OE unit), he never replied to my second (or third) emails. So, I cannot say I recommend CHP due to poor customer service. This was after I spoke with one of his staff. She assured me that Lyle answered all emails on a daily basis. I tried to contact him, over the phone, but he never seems to be in the shop. Disappointed, I am.

Wednesday, May 18, 2011

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.

Monday, May 16, 2011

Electrical Gremlins are not home

I finally had an opportunity to remove some bodywork and check the electrics. After chatting with Sudco a couple of weeks back, I may have interpreted the hesitation issue as fuel related. It's possible it might be electrical. So, I exposed as many items, on the NX, as the shop manual mentioned. First up was the CDI and the Coil. There really isn't a test for the CDI box itself. There are some resistance and continuity checks for the wiring that plugs into the CDI. All readings were within spec. Next was the coil. Again, everything was in spec. So, I made sure that the connections were tight and the wiring insulation was free of cracks and/or exposed wires. Everything looked good and nothing untoward was discovered. Next up was the regulator/rectifier. Again, everything checked out as being within specification and all wiring connections were clean and tight. The only thing I was unable to check was the timing. I do not own a timing light and I'm wondering if a timing issue would appear and then disappear like this problem has. If necessary, I can take the NX to the dealer for a quick timing check. I have a call and an email in to Classic Honda to see if anyone there can assist. The search continues...

Wednesday, May 11, 2011

More Thoughts on the Bushwacker

While I hadn't had time to determine what, if any, electrical gremlins I may have (btw, the NX is now running great), I have had an opportunity to evaluate the Olympia Bushwacker in higher temps.

Chicago has had a pretty damp and cool Spring so far but this week has seen conditions resemble late June rather than mid-May. Humidity has been high with the threat of afternoon thunderstorms each day. Temperatures have also been high, mid-to-upper 80s. So, I removed the liner from the Bushwacker and rode home from work. The temps, according to my 'Droid were in the upper 80s. The jacket vented well and at no point did I feel warm/hot while I sat in rush hour traffic. Obviously, I had to adjust the armor positioning straps since the liner's bulk is now missing. Otherwise, I was impressed and comfortable. Having the jacket be a light color (hi-viz), contributes to a lack of solar gain. This will be most helpful during mid-Summer when temps approach the 100º F mark. This morning, when temps were about 20º F cooler than yesterday afternoon, I rode without the liner to specifically test the lower temps limit (w/o liner). The jacket was sufficiently warm since the mesh panels tend not to be on "leading edges", that is the tops of arms and shoulders. I would think on a bike with a windscreen or full bodywork, the threshold might even be lower since your body is (mostly) out of the air stream. I have yet to experience rain but I carry the liner so, I'll be ready.

Friday, May 6, 2011

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.

Thursday, May 5, 2011

Situation Normal, ......

All Fouled Up.

I thought I was making some progress with respect to getting the carburetor to properly meter air and fuel. It's doing the job alright (as it always has been) but it's not doing it as efficiently as it should (or as it did from the factory). I continue to deal with the hesitation/surging issue. It's very subtle but when things are right, the motor runs great and pulls well (for 125cc). When it's 'off', it's noticeably down on power. I experienced both scenarios on the ride to work this morning. So, obviously I haven't resolved the issue.

While I was shopping for o-rings, last weekend, at the local (industrial) hardware store (that caters to the trades), I met one of the employees that happened to have some familiarity with the carburetor I had in my hand (the one from the ATC200X). His suggestion, should I fail to make either the OE or ATC carburetors work, was to get a replacement from that large on-line auction site. Apparently those "Chinese knock offs" are pretty good. He's used them on more than one occasion. The issue is that one only seller seems to carry them for the NX. And, while they look correct on the outside, I'm curious what the measurements are, especially the venturi and jet sizes.

I did contact them, previously, regarding a rebuild kit (before I knew the true nature of the problem (although, I'm not quite sure if I really grasp the entire issue). However, they seem to be a little hard to get a hold of lately. They do have a good return policy (30 days) but I would prefer not to pay the shipping, both ways, if I don't have to. The price isn't terrible ($65) but I'm leery of ordering something without a little additional information. Perhaps I can see if they have a non-Toll Free number.

Tuesday, May 3, 2011

Progress slowed by weather and old age

While the variable weather that's plagued the Midwest with soggy conditions has eased, old age and use are taking their toll (on the NX, not me). The past few weeks haven't been the best with respect to riding conditions. We've seen a lot of rain and cool temperatures. And, when the two happen to coincide, it just feels colder than it actually is. So, there hasn't been much opportunity to swap carburetors and experiment with chemicals.

I think I may have made some progress though when it comes to resolving the issue caused by the degradation of the carburetor body. I honestly thought that using Teflon tape would be just as good as using the Gasolia E-Seal pipe dope. But, it seems as if I was wrong.

This past Saturday's weather was conducive to working on the bike and attempting to tune the carburetor after the re-install. However, the float bowl gasket (seal) decided it was time to pack it in. After swapping all of the internal bits to the ATC200X carburetor body, the NX ran it but it needed no choke to get it started. This rich condition was obviously going to be an issue once the motor warmed up. Before the engine could even get hot, though, I noticed gas leaking between the float bowl and the carburetor body. I feared that the float valve had failed to seal. So, I removed the carburetor and swapped in the ATC float and float valve. After re-install, it continued to leak. So, I swapped everything back into the original carb body fearing there was something inherently wrong with the ATC carburetor body. Unfortunately, the leak persisted indicating that what I thought was the issue, bad float or float valve most likely wasn't the issue at all. So, I obviously need a new float bowl seal. Naturally, these come as part of a "rebuild" kit but I'm sure the carb could use a few of the other gaskets/seals as well.

I did take advantage of all of the disassembly/assembly steps to use the E-Seal on the threads of the emulsion tube. I was really disappointed to notice a green/blue tint to the gas (the E-Seal is colored a bluish green) remaining in the float bowl after the first disassembly. It appears that you have to wait for the E-Seal to set up (24 hours) before it's ready for use. That stinks. On the last go-round, where I switched everything back, I applied fresh E-Seal to the emulsion tube and Permatex Ultra Blue RTV Gasket Maker to the old float bowl gasket. Well, the RTV stopped the float bowl leak (I knew it would, that stuff is awesome). And, it appears that after a twenty-four hour cure period, the E-Seal is doing what I thought it would do; cure the lean condition which causes the hesitation. At this point, I've only ridden about 33 miles on the "repair" but it seems to be working. The hesitation has lessened considerably and the motor will pull from 2500-3000 rpm (before, anything that low would require a down shift). I know that 125cc isn't going to generate much torque but being able to accelerate from those rpm is an indicator that things are getting better.

Wait, better but not fixed? I'm hesitant to proclaim "mission accomplished" but am encouraged by the results. I believe that (partially?) resolving this issue has revealed another; a lean condition at high rpm. More than one  "outside voice" has suggested that the main jet is too lean. I was hesitant to richen it up because I knew that the NX ran properly from the factory. Now, we know that the manufacturers like to jet the carburetors lean to pass emissions. But, I wanted to get the bike running properly before any additional tuning. If we're at the same point in a week's time, I may declare victory and try a richer main jet. However, I'll need that rebuild kit because messing with RTV each and every time will get counter productive. Or, if I can source a float bowl with a "jet port" (threaded bung in the float bowl for the express purpose of easily swapping jets), I may tinker sooner.