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.

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