Rear cyl Pop and backfire!!

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Mar 19, 2020 | 03:46 AM

Nautilus

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From: Tegucigalpa

Rear cyl Pop and backfire!!

Good day peeps. Hope you're all safe from the coronavirus and taking safety measures.

That being said, I'm in dire need of help from you guys. I have trouble with my 1995 Fatboy. It suddenly started popping and backfiring the rear cylinder and I have done a few things already but still having the same problem. To keep things short, this is how it started:

Bike was running fine and it started with a slight pop to which I thought was dirty fuel. Switched gas stations and popping disappeared. Then it came back to the point I couldn't ride anymore! I had to get back home on one cylinder!! Took a look at the plugs and noticed the rear one had some soot on it. First I thought it might be intake and exhaust leak so I replaced the seals. Bought both and replaced them with high quality ones and replaced the spark plugs. Ran fine for a couple of miles and then I went limping home again on one cylinder. Took the general "WD-40" to the intake manifold test and no leaks were present. Figured might have been some dirt in the CV and cleaned it up, purchased a rebuild kit and rebuilt it. Problem persisted. I continued and addressed the ignition, bought a new ignition control module. Figured I could just upgrade it anyways. Ran good for a day then the problem returned. I completely replaced the carb and it still has the problem.

I'm starting to thing I'll have to tear it apart but I don't want to do that until it's the last thing since the engine has approximately 35k miles on it (that I know of).

Any ideas?

Mar 19, 2020 | 05:49 AM

98hotrodfatboy

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Joined: Mar 2010

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From: Poolville

Have you tested your coil and coil wires?

Mar 19, 2020 | 06:09 AM

Yankee Dog

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Joined: Apr 2007

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From: Brighton, MI

Cam/nose cone pick up sensor original?

Problem start after bike warms up?

Do do a search on cam sensor...remove cover and inspect if it’s an original...YD

Mar 19, 2020 | 06:43 AM

Hey Man

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From: West Central FL

Check for exhaust leaks at the heads and for possible cracks in the pipes. Also check for intakes while you're at it.

Last edited by Hey Man; Mar 19, 2020 at 06:47 AM.

Mar 19, 2020 | 06:46 AM

RANGER73

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From: Beyond Fucital

C. All of the above.

Mar 19, 2020 | 03:37 PM

Nautilus

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Joined: Sep 2009

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From: Tegucigalpa

Quote:

Originally Posted by 98hotrodfatboy

Have you tested your coil and coil wires?

Yea, replaced EVERYTHING for the ignition, module, coils, pickup sensor, spark wires and spark plugs.

Mar 19, 2020 | 03:47 PM

Nautilus

Thread Starter

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Joined: Sep 2009

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From: Tegucigalpa

Quote:

Originally Posted by Hey Man

Check for exhaust leaks at the heads and for possible cracks in the pipes. Also check for intakes while you're at it.

I did check for leaks spraying carb cleaner and WD-40 at the manifold and exhaust, no leaks have I detected.

Quote:

Originally Posted by Yankee Dog

Cam/nose cone pick up sensor original?

Problem start after bike warms up?

Do do a search on cam sensor...remove cover and inspect if it’s an original...YD

Bike starts right up, but it immediately starts popping and backfiring. While running tests it backfired so hard it blew the carb off the manifold.
Cam sensor? You mean the pick up sensor at the "V" squared medallion? If it is, it got replaced.