Back Fire

swens55 · 07-25-2011, 04:27 PM

I recently bought a 05 1600 Nomad. It has V/H pipes with Power Commander. I remapped it this morning so I'm sure everything is good there but I get a very loud backfire when decelerating. Iv'e got great power, but the backfire is like a gunshot, very loud. Doe's
anyone have an idea what the problem could be if there is one? Otherwise the bike runs great.
Thanks,
swens55

cactusjack · 07-25-2011, 04:39 PM

It's running too rich. Unburned fuel is combusting in the exhaust, causing the backfire. Another possibility could be a leak at the exhaust pipe where it contacts the head.

macmac · 07-25-2011, 05:33 PM

I agree with Cj. Try holding a little throttle when you down shift. Just to see if leaning the mix out any works.

**ringadingh** · 07-25-2011, 07:57 PM

Theres a good chance that your rear header pipe is cracked at the first bend where it comes out of the cylinder. V&H pipes are common for that happening. You can check the pipe with a mirror behind the heat shield.

swens55 · 07-25-2011, 08:47 PM

Thanks for the input. I did notice that a slightly open throttle during deceleration decreases the amount of back fire. One more thing I found after pulling the right air intake cover is evidence of a slight puddle at the bottom of the cover and the front cyl intake seems excessivly wet.

VulcanE · 07-26-2011, 08:29 AM

I'm surprised no one has mentioned it, but does the bike still have the reed valves? When you add aftermarket pipes, and the reed valves are still functional, You will get backfire on decel. You will need to "marble" the intake for the reed valves, or remove them and replace them with "coasters".

macmac · 07-26-2011, 11:58 AM

What is the puddle and where is it exactly? It pretty much has to be fuel, or oil/water from the engine breather.

And yes Vulcan has a most excellent point. Are the reed valve disabled, since they should be.

jd01 · 07-26-2011, 12:08 PM

+1 on the marbling or reed valve and "Medusa's head" removal.

**markclark57** · 07-26-2011, 05:22 PM

The backfire on my '06 (w/ PCIII and Cobra TrueDuals) went away when I installed Joe "Chuckster" Noris' single plate intake kit. I've heard of the Marble trick too, I jumped ahead to the intake mod instead.

07-25-2011, 04:27 PM	#1
swens55 Jr. Member Join Date: Jul 2011 Location: Williams, Arizona Posts: 14	Back Fire I recently bought a 05 1600 Nomad. It has V/H pipes with Power Commander. I remapped it this morning so I'm sure everything is good there but I get a very loud backfire when decelerating. Iv'e got great power, but the backfire is like a gunshot, very loud. Doe's anyone have an idea what the problem could be if there is one? Otherwise the bike runs great. Thanks, swens55 Login or Register to Remove Ads
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07-25-2011, 04:39 PM	#2
cactusjack Mega-Contributor Join Date: Sep 2007 Location: Where it doesn't snow...ever! Posts: 21,926	Back Fire It's running too rich. Unburned fuel is combusting in the exhaust, causing the backfire. Another possibility could be a leak at the exhaust pipe where it contacts the head. __________________ Scott "Cactusjack" Hanks VBA #00105 H.O.G. #4250060 2011 H-D Ultra Limited 103ci :: 2011 HD Electra Glide Ultra Limited w/Stage 1 :: Rallies: Mesquite '08\|Custer '09\|Cortez '10\|Crescent City '11\|Kanab '12\|Antlers '12\|Estes Park '13\|Antlers '13\|Orofino '14\|The Dalles '17
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07-25-2011, 05:33 PM	#3
macmac Sr. Contributor Join Date: Apr 2008 Location: Tamworth New Hampster 06 1600 Posts: 12,484	Back Fire I agree with Cj. Try holding a little throttle when you down shift. Just to see if leaning the mix out any works. __________________ 06 1600 Nomad Just call me Mac molon labe come and get it
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07-25-2011, 07:57 PM	#4
ringadingh Join Date: Aug 2007 Location: Newmarket Ontario Canada Posts: 35,387	Back Fire Theres a good chance that your rear header pipe is cracked at the first bend where it comes out of the cylinder. V&H pipes are common for that happening. You can check the pipe with a mirror behind the heat shield. __________________ 2002 Nomad aka Bountyhunter VBA #27 VROC #18951
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07-25-2011, 08:47 PM	#5
swens55 Jr. Member Join Date: Jul 2011 Location: Williams, Arizona Posts: 14	Back Fire Thanks for the input. I did notice that a slightly open throttle during deceleration decreases the amount of back fire. One more thing I found after pulling the right air intake cover is evidence of a slight puddle at the bottom of the cover and the front cyl intake seems excessivly wet. Login or Register to Remove Ads
	0

07-26-2011, 08:29 AM	#6
VulcanE Sr. Member Join Date: Jan 2008 Location: Cartersville, Georgia Posts: 4,838	Back Fire I'm surprised no one has mentioned it, but does the bike still have the reed valves? When you add aftermarket pipes, and the reed valves are still functional, You will get backfire on decel. You will need to "marble" the intake for the reed valves, or remove them and replace them with "coasters". __________________ Cliff "VulcanE" Evans 2005 Blue & Silver 1600 Nomad VBA # 320 VROC # 20381
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07-26-2011, 11:58 AM	#7
macmac Sr. Contributor Join Date: Apr 2008 Location: Tamworth New Hampster 06 1600 Posts: 12,484	Back Fire What is the puddle and where is it exactly? It pretty much has to be fuel, or oil/water from the engine breather. And yes Vulcan has a most excellent point. Are the reed valve disabled, since they should be. __________________ 06 1600 Nomad Just call me Mac molon labe come and get it
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07-26-2011, 12:08 PM	#8
jd01 Advanced Member Join Date: Feb 2008 Location: Canton,Georgia Posts: 851	Back Fire +1 on the marbling or reed valve and "Medusa's head" removal. __________________ Don Denman "JD" 2001 Luminous Vintage Red carbed 1500 Nomad VBA #376 VROC #6195
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07-26-2011, 05:22 PM	#9
markclark57 Join Date: Jun 2010 Location: Phoenix, AZ Posts: 3,108	Back Fire The backfire on my '06 (w/ PCIII and Cobra TrueDuals) went away when I installed Joe "Chuckster" Noris' single plate intake kit. I've heard of the Marble trick too, I jumped ahead to the intake mod instead. __________________ 2006 Vulcan 1600 Classic "George III" (Patricia's) 2006 Vulcan 1600 Nomad "Grace" (Mark's) Mark Clark VBA #1619 TaibhseDaid@Gmail.Com "Irish" @ Maricopa County Chapter of B.A.C.A. Phoenix, AZ
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