Thursday, April 7, 2011

Magical Repairs

I continue to deal with the pixies that inhabit my carburetor. I must have appeased them, on the way home last night, as suddenly the NX started running as I think it should. There have been a few moments, over the past few weeks, when something happens that causes the motor to run great. I liken it to experiencing the end of a cold, when your inflamed nasal passages finally clear and you can breathe freely, through your nose, once more. On more than one occasion I've had someone say; "run the piss out of it, it'll eventually clear out". Those statements are, no doubt, relayed along because 1) it worked for the person saying it and 2) there is some truth in it as it applies to older motors (motors that aren't encumbered by all sorts of electronic sensors). I take statements like this with a grain of salt because A) they usually don't work (for me) and B) I try to be easy on my equipment (I usually work on everything I own and hate paying to fix something that wouldn't have broken had I not treated it harshly).

A lot of my mechanical expertise comes from working on mid-60s muscles cars; more specifically Mustangs (including Shelby GT-350s). I've also raced a 1967 Austin-Healey Sprite Mk IV in SCCA's F Production class. There were times when "running the piss" out of one of these cars actually did some good. However, cleaning out the carburetor was usually a manual process that involved disassembly, cleaning, reassembly and re-installation. Carburetors have a tendency to not "clean themselves". There are too many passages and small orifices that will clog and not become unclogged by simply running more and more fuel (with or without cleansing additives) through the carburetor.

Getting back to the NX, I would consider the carburetor to be "old school" in that it requires some cleaning/maintenance on a regular schedule but the bike also has electronic ignition (which the previously mentioned cars did not - I eventually installed a crank-trigger ignition on the Sprint but that's another story). So, the NX's CDI and regulator/rectifier should either work or not work. They seem to be working. The only item left that has some type of 'variable' condition is the carburetor. And, since it seems to be running great now, I'm hesitant to mess with it. One of the ways that I've determined if the motor is running properly is how it performs while in fifth (top) gear. Recently, a shift into fifth (usually around 45-50 mph) results in sluggish performance and a slow loss of rpm/mph until it's necessary to down-shift into fourth. Both yesterday and today I was able to accelerate in fifth (today while encountering a head wind, no less!). So, unless (until?) it reverts to its (evil/nasty) previous condition, I'm leaving it alone.

Discovery

I was able to determine way the fender flap was being sucked up under the front fender; it's due to deflection caused by a front suspension compression. In English, that means that when the front forks (violently) compress, say rinding over a curb/gutter, the flap is soft enough to not react to the compression (quickly enough). This causes the bottom of the flap to encounter the front tire tread (which has some deep sipes) and subsequently be sucked up between the tire and the fender. I happened to be riding helmet-less (yes, bad) because I was listening to the way the motor was running while in motion. I rode hard over the gutter, at the end of the driveway, and then heard one of the plastic flap-supports get sucked up. A few more "tests" confirmed my suspicions. I now watch for things that could cause similar circumstances; curbs, potholes, rough railroad crossings, etc. In these cases, I'll have to slow down some. For the gutter at the end of the driveway I can ride across it at more of an angle which lessens the jolt enough to keep the flap away from the tire.

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