K&N air filter causing backfire through exhaust


Information and questions on GL1500 Goldwings (1988-2000)
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Howlin88
Posts: 3
Joined: Mon Jun 20, 2016 10:59 am
Location: Coeur d'Arlene, ID
Motorcycle: 1988 honda goldwing 1500

K&N air filter causing backfire through exhaust

Postby Howlin88 » Mon Jun 20, 2016 1:12 pm



Hello all, I've been searching through and haven't found anything yet. Just bought a 1988 goldwing 1500 For 1200 bucks! Yey me, and the price should also tell you a little about the condition of the bike. Finally got it running right ish but I cannot get it to stop backfiring under deceleration. The previous owner put in a k&n air filter which is great, but neglected to do the supporting mods like rejet. So now it's up to me to correct this little oversight. Any suggestions on the correct jets to at least get me in the ballpark? I've already done a full tuneup and will be changing the cruise amd sub air filters this weekend, don't know if it's running as strong as it should be as this is my first one. I have noticed what seems to be a flat spot in the powerband between approximately 2700 And 3300 or so, don't know if this is related or not but suspect it is. The bike only has 70k on it and we all know they are good for much more than that! Any help or advice would be appreciated.



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MikeB
Posts: 1228
Joined: Fri Dec 04, 2009 12:54 pm
Location: Tacoma, WA
Motorcycle: 1998 - GL1500 Aspencade.
2003 - GL1800A

Re: K&N air filter causing backfire through exhaust

Postby MikeB » Mon Jun 20, 2016 3:53 pm

Replacing carb jets is not needed with the installation of a K&N filter. The backfiring is being caused by something else.
Replace the spark plugs and take a look at the ignition wires. Backfiring through the exhaust is usually caused by un-burnt fuel in the exhaust which is sometimes caused by spark plugs not firing like they are supposed to.

By thew way, if you do get around to replacing the K&N filter with an OEM filter, you will most likely need new rubber o-rings around the perimeter of the air filter housing cover. There are two of them that are supposed to be removed when the K&N filter is installed. They are part number 17213-MN5-300.
MikeB
Tacoma, WA, USA

Howlin88
Posts: 3
Joined: Mon Jun 20, 2016 10:59 am
Location: Coeur d'Arlene, ID
Motorcycle: 1988 honda goldwing 1500

Re: K&N air filter causing backfire through exhaust

Postby Howlin88 » Mon Jun 20, 2016 5:23 pm

Thanks Mike for the input, I really appreciate it. I'll check the plugs and wires to make I'm getting solid spark. Hopefully that'll fix the problem, if not I guess it'll be back to the drawing board.

harvey01
Posts: 631
Joined: Thu May 31, 2012 7:14 pm
Location: Henrico, Virginia
Motorcycle: 2004 GL1800

Re: K&N air filter causing backfire through exhaust

Postby harvey01 » Mon Jun 20, 2016 7:13 pm

You might also check all vacuum lines to see about a leak. Also check around the manifold for leaks.
harvey
Ride Safe and Ride Often

CrystalPistol
Posts: 265
Joined: Wed Mar 10, 2010 9:07 pm
Location: Shenandoah Valley of Virginia
Motorcycle: 1985 GL1200A
1997 GL1500SE Lehman Trike

Re: K&N air filter causing backfire through exhaust

Postby CrystalPistol » Mon Jun 20, 2016 10:19 pm

Also, a leak in the exhaust system can lead to back firing on deceleration.

I agree, K&N does not require rejet on the GL1500.
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spiralout
Posts: 1050
Joined: Sun Feb 17, 2013 6:41 pm
Location: Alabama
Motorcycle: 1975 GL1000 (gone)
1980 GL1100I (with '77 1000 engine)
1996 GL1500 SE

Re: K&N air filter causing backfire through exhaust

Postby spiralout » Wed Jun 22, 2016 11:22 am

Plug wires out of order can cause that, also.

Howlin88
Posts: 3
Joined: Mon Jun 20, 2016 10:59 am
Location: Coeur d'Arlene, ID
Motorcycle: 1988 honda goldwing 1500

Re: K&N air filter causing backfire through exhaust

Postby Howlin88 » Wed Jun 22, 2016 5:11 pm

Finally found the problem, a carb boot is leaking. I guess that's just part of working on a 30 year old bike lol. Gonna start tearing it down this weekend to fix it. Thanks for all the help, hopefully it'll be fairly easy.




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