Help Carb issue
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Stage III
Joined: Apr 2013
Posts: 3
Likes: 0
From: NH
Help Carb issue
hey guys, 98 softail cv carb. Ive had this bike a while and its always had a "pop" in the carb, usally after it idles for a while and I hit the throttle or come to a stop and go to take off, what ive done so far.. adjusted air fuel, checked for vac leak, changed the jets from 42 to 45 and 170 to 175, replaced the accelerator pump diaphragm had a hole in it! and replaced the vacumme petcock due to leaking! still has the "pop" any ideas would be apprecieated!!
Outstanding HDF Member
Joined: Oct 2010
Posts: 2,706
Likes: 14
From: Near Frankenmuth, MI
Welcome. It's typical new posters start on the welcome board. But many post questions with their first post. Glad to see you found the forum and the correct place to ask your question.
Typically a pop occurs when hot gasses seep out through a leak somewhere prior to the baffle. When you have it warmed up look for escaping exhaust. Could be at the manifold, could even be where the pipes should seal to the baffle.
If your sure it's coming out the carb it may mean you have valve seal issues.
Be certain your timing is on. Make sure your plugs are fresh, even the plug wires could be causing an intermittent spark. You get a build up of gas and then a hot intermittent spark ignites it.
You could have carbon build up on the pistons that is causing a hot spot and pre-ignition giving you a pop.
One other thing I can think of may be a bad float adjustment allowing excess gas to seep into the carb.
I look forward to see other suggestions about this too.
Typically a pop occurs when hot gasses seep out through a leak somewhere prior to the baffle. When you have it warmed up look for escaping exhaust. Could be at the manifold, could even be where the pipes should seal to the baffle.
If your sure it's coming out the carb it may mean you have valve seal issues.
Be certain your timing is on. Make sure your plugs are fresh, even the plug wires could be causing an intermittent spark. You get a build up of gas and then a hot intermittent spark ignites it.
You could have carbon build up on the pistons that is causing a hot spot and pre-ignition giving you a pop.
One other thing I can think of may be a bad float adjustment allowing excess gas to seep into the carb.
I look forward to see other suggestions about this too.
Seasoned HDF Member
Joined: May 2008
Posts: 21,129
Likes: 12,690
From: South Carolina
A lean condition will cause backfiring through the carb.
Make sure the accelerator pump is actually pumping fuel.
Be sure there is no intake leak. Intake seals at the head, the vacuum hoses etc.
Make sure the accelerator pump is actually pumping fuel.
Be sure there is no intake leak. Intake seals at the head, the vacuum hoses etc.
Thread Starter
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Stage III
Joined: Apr 2013
Posts: 3
Likes: 0
From: NH
Thanks guys, im going to work on it again tonight, Ill recheck for an intake leak but seems tight, I replaced the accelerator pump because it wasn't working, pumps great but still pops, making me slightly nuts!! im replacing the upper slide diaphragm and top cover tonight there was a hole in the cover and what looked like melting on the plastic piece. thanks again Ill let you know how it works out!!
Thread Starter
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Stage III
Joined: Apr 2013
Posts: 3
Likes: 0
From: NH
Ok, everything in the carb is NEW! Including vac petcock! I checked the vacuum lines with a hand held vac and it held the vacuum till I released it. With the bike running I sprayed around the intake with carb cleaner then I checked it again with wd40 no leak there! Then I checked for an exhaust leak and that turns out to be tighter than my bosses wallet! It stopped popping after I drove it for 20 minutes? Timing maybe? I haven't rechecked the plug color as of this last try I wanted to let it cool!!
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