+1 Ol' Blue took 3 complete tear downs and soaking in berrimans to get those damn VM carbs cleaned. My 92 NH took 2 cleanings and a couple tanks with seafoam to clean it out. If it is so lean that it regularly missfires that can make for a black plug too. Because the gas builds up in the cylinder on the missfires and when it fires again it is rich. Do you have an infrared thermometer? If so point it at the pipes you should get a consistent reading. Does it seem to be an all the time problem, occur at idle, or it happens at mid/full throttle? If mid/full throttle I'd suspect the emulsion tubes are clogged up on that carb. For some mysterious reason Ol'Blue had that problem last year. Out of nowhere whenever I'd run it hard grit would get in the emulsion tubes. I never did figure out where it came from. It jut took 3 cleanings to get it all out.
Allen Thomas On Mar 12, 2015 10:43 PM, "Graham Rogers" <[email protected]> wrote: > You checked compression on that cylinder right? How many miles have you > put on it since the carb clean? A couple hundred might make a difference. > If you take the carbs apart again and clean them, switch the jets with one > of the outside carbs, see if the problem switches to that outside carb. I > have often had to remove and clean the carbs more than once on the same > Nighthawk. I had one that sooted up the plugs, drove me batty until I > replaced the battery, Graham > > Sent from my iPad > > > On Mar 12, 2015, at 21:56, Tommy Hill <[email protected]> wrote: > > > > Dropping a spark could cause it to turn black? Possibly bad plug wire? > I will check that. Does the fact that the black is mostly on one side of > the plug have any bearing? > > > > I did the carbs and the mech reinspected. The jets are not > interchangeable and I have no extra parts. The vac comes off of #2 AND I > just rebuilt the vacuum side of the petcock. Good thoughts, though. > > > > -- > > You received this message because you are subscribed to the Google > Groups "Nighthawk Motorcycle Lovers!" group. > > To unsubscribe from this group and stop receiving emails from it, send > an email to [email protected]. > > To post to this group, send email to [email protected]. > > Visit this group at http://groups.google.com/group/nighthawk_lovers. > > For more options, visit https://groups.google.com/d/optout. > > -- > You received this message because you are subscribed to the Google Groups > "Nighthawk Motorcycle Lovers!" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/nighthawk_lovers. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "Nighthawk Motorcycle Lovers!" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/nighthawk_lovers. For more options, visit https://groups.google.com/d/optout.
