Harley Davidson Forums banner

Black Smoke and Backfire (Spitting)

9K views 3 replies 4 participants last post by  GotGold 
#1 ·
Background story: 1996 Dyna LowRider. First H-D. Bought used in October. I have already replaced the voltage regulator, stator, had two pulley bolts shear (one Heli-Coiled) the rest are still not holding with loctite red, one flat tire, and had one bad driver who decided that the light should be green even though the truck and motorcycle in front of her had not yet moved (because the light was red - dented fender and lost tail light lens). Trying not to refer to H-D ownership as misery, but here's my current issue:

My Issue:
I had annual service done by a reputable shop in March. Less than 500 miles since then. But I had not ridden for 3 weeks and was going over the bike in preparation for a ride. I checked the oil and had to put in about 1/3 of a liter to bring it into the acceptable range. I just happened to take off the breather and noticed that the air filter had not been changed. There was some build-up on the carb so I sprayed it with carb cleaner with the intention of starting it right up. One emergency later, the bike was not started for three more days with the carb cleaner sitting in the carb. When I started riding, it had a tendency not to maintain idle and it was bogging down (not like a bad float - just a sputtering), and some minor backfiring (spitting) from the tailpipe when the throttle is released. I checked the plugs for fouling, and they appeared to be wearing normally. I also adjusted the idle speed to keep it from shutting off - this brought the idle speed to 1200 rpm. When I re-checked the oil after this, it had turned black (again, less than 500 miles since service).

I'm pretty handy but suck at diagnosing this stuff.
 
See less See more
#2 ·
The oil will turn dark or black quickly, dont worry about that.

The carb cleaner might have caused something to dry out but more likely an intake leak developed on its own. Thats what it sounds like. Check the intake. A 21 year old carb could probably stand some love anyway with a good cleaning and rebuild kit.
 
#3 ·
Spray carb cleaner on the intake. It should not change the idle, if it does you have a leak as Pete suggests
 
#4 ·
Letting that carb cleaner soak, probably caused some crud to break loose and go someplace it shouldn't. I'd go with what Pete said. Get a rebuild kit and clean that carb.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top