I recently purchased a 1988 Honda NX125. So recently, in fact, that I don't even possess it yet (as of this writing). However, while researching the bike, I discovered a dearth of general internet knowledge regarding this motorcycle. I was able to find quite a bit of information on the NX250 and NX650 models. I would expect some "cross pollination" across the NX line but, with the 250cc model being water cooled (the 125cc and 650cc engines are air cooled), there may not be as much as I expect. I also happen to own a 1989 Honda TransAlp (which is a water cooled 600cc v-twin) and have already noticed some similarities between the little NX and the bigger TA.
The bike I bought is about as pristine as one would expect for a twenty-two year old bike with 2042 miles. I'm the fourth owner. The previous owner (Tony) bought the bike with a blown motor and has put all of about one hundred miles on it since he had the engine rebuilt. In all fairness to Tony, he's more into cruisers and I'm not surprised this little buzz bomb didn't see much 'action'. According to Tony (and I have no reason to doubt him), owner #2 ran the engine low on oil (the sump is only one quart) and proceeded to wipe out the cam and one valve. So, Tony had a local cycle shop (someone he trusted) rebuild the motor. He rode it so little (as previously mentioned) that I still have four hundred miles to go before the break-in period is complete. In addition to the bike, Tony also has a spare motor, the owner's manual and a shop manual. So, between the bike and the two manuals, I should be able to help with any questions regarding "from-the-factory" configuration. Additionally, that spare motor may come in handy with respect to questions regarding engine internals.
Some background; this will be the sixth motorcycle I've owned. I started out, in the early 90s, on a 1986 Honda Reflex (TLR200) which was Honda's street version of their trials bike (RTL200). I then progressed to a 1997 Suzuki DR350SE which, in turn, was sold for a 1999 Suzuki DR350SE (better suspension than the '97). In the summer of 2010, I decided I needed something a little more highway worthy yet still dirt capable. The DR was sold for the above mentioned TransAlp. Along the way, I picked up a 2002 Honda Reflex (scooter) for my wife. Even thought it appears I'm a huge fan of "Ride Red", that's not necessarily the case. I loved both of my DRs and if you're looking for a "do it all" dual sport, you cannot go wrong with that choice (I'd highly suggest the last two model years, 1998-99) if you go that route. Owning a stable of Honda products is just the way things have worked out.