My sportster is running rich


New Member

Recently i have noticed that my sportster is running rich. I don't have the stock pipes or intake on it. I can drive it and after about 50 60 miles it starting missing a little. I've not a black sut around the outside of the carb. Ive just the inside of the carb and its as clean as can be. I have also adjust the fuel just to almost were the engine is barely getting any gas but it still seems to run rich. Anyone know what is causing this? :15:
First thing I would check is the air filter, if it is a K&N , it may be time for a cleaning. If it is a paper filter, it may need replacement. That's usually the indication of a restricted intake when it runs rich without any further mods.

How are your plug wires and plugs? recent? Miles on them?

Check your enricher on the carb to make sure it is fully closed after warm up and not creaping open with vibrations.. This wil introduce additional fuel and load things up a bit.

Take a look here for the adjustment.
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It makes it much easier to give advice with a few facts about the bike like year ,mods, recent upgrades, miles etc.

Have you checked the resistance in the wires with an ohm meter or just going by looks?
its 1981 harley sportser 1000cc, drag pipes, and new s and s air cleaning, and 40 mm bendix carb. with and adjustable main jet. and its go around 15 grand miles. it runs real good as long as I have new plugs in it and after about 40 miles they get smoke up like. I've also notice the sutty stuff around the carb. And i have not check the resistance in the wires. Ive got 8mm axcel plug wires.
First things first, how long have you had the drag pipes on it?

They can raise heck with mixtures and at lower rpm's they will load up as well as loose torque. There is a big reversion problem caused by the drags because of no back pressure which could also be your problem with the sooty deposits around the carb from the reversion.

I would lower the adjustable main jet (lean) to see where that takes you for starters by a bit. If you have to run the drags, I would suggest the butterfly in the end of the pipe to give some backpressure and it will actually run better with no noticable sound difference.

Here's an idea of what you have to do using a bolt with a washer welded to it for backpressure which can be turned to tune the flow seen below in the bottom pic.

Here's another way to solve the backpressure issue using the drag pipes.
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Thanks. Ill try putting the old pipes on and see if that fixes the problem and if i does then i'll do one of those to things you suggested to get some back pressure