I have a 2000 Harley-Davidson, v-twin, heritage springer softail, that I have had the carb changed on it, whic

Question

h I have had backfiring problems on deceleration. Any advice on how to get rid of this backfiring would be appreciated. thanks...plugs and wires and everything else has been changed.

Answer 1

Based on the short facts provided, I'd agree with everyone who says you're running too lean. Carb farts are usually caused by a lean condition(not enough fuel to air ratio). Since it ran allright(I assume) before you changed carbs, try going to the next size up jets for your new carb and see if that helps. Don't continue to run in a lean condition for too long as it will mess up your valves, etc. Harleys are designed to run rich in order to help cool the combustion process.

Answer 2

Backfiring on deceleration is usually a sign of a lean condition.
Take a look at the plugs, there should be a tan coloration on the ceramic portion of the plug that surrounds the electrode.
If that part of the plug is white or very light, you will need to richen it up.
The fuel air mixture screw offers a slight adjustment for lower speed mixture ,but most likely you will need a larger jet.

There is always a possibility of a vacuum leak ,but seeing as you just changed the carb. I would focus on that first.

Answer 3

Backfiring on deceleration is caused by a lean mixture.
Honda's in the 80s had that problem and started putting an "air cut off" valve on the carbs to cure the problem.
Kawasaki Vulcan 750s have that problem.
The cure is to richen the idle mixture screws (turn out, counter clockwise).
Before you go crazy trying to figure out the problem, richen the idle mixture screw, 1/2 turn at a time to see if that will fix it.
Count how many turns of the screw you make, so you can turn it back to the original position if it has no affect.
Send me your email address so I can forward a copy of a carb trouble shooting guide.
It will explain what to adjust, to repair specific problems.

Answer 4

Technically its after fire not backfire as its in the exhaust not carb
Did you change the pipes as well?
It may be you have air leaks, not enough back pressure or just wrong pilot jetting .
The original carb has Air Cut Valve (or transient enrichment circuit)
Getting it on a dyno with gas analyser may be the quickest thing to get it sorted and will find all the power you have paid for (a friend used to run dyno in Harley shop and could 'find' 10~15 HP with carb and exhaust changes

Answer 5

Check the "rubber bands" that connect the carb manifold to the intakes on the cylinders for air leaks. Its a common problem when a carb is changed out that shows up as backfire at deceleration.

A easy way to check is to get engine running at normal temp
Spray some WD-40 at the rubberbands / intake manifold and listen for the engine RPM's to drop. Drop in RPM = air leak at bands...

Answer 6

2000 Heritage Softail

Answer 7

Definately look at the intake manifold. The "rubber bands" are a primary suspect, but one way to find out for sure is to run the bike slightly above idle and use a hand spary bottle to shoot a light mist onto the intake manifold as you do. If it blubbers at all...there's your culprit.

Another area is the exhaust gaskets on the head to pipe juncture. If you blew out one...or if they are vreally loose, occasionally some air can back up through the exhaust valve, causing some popping.

Answer 8

Mine POPs through the pipes if it's too lean. Usually, I turn the idle mixture screw 1/4 turn to richen it, and the popping goes away.

Answer 9

If you cant answer that yourself you need to take your harley, trade it in and get your self a 90 honda trail now!!

Answer 10

Is it running too rich? Check that; it's likely the problem.