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Aug 11, 2006 | 10:16 AM

axx6912

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Stage IV

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backfire problem

HI everyone, new to site here.

Have a problem with backfire problems on my 05 1200C. About 3 weeks ago it started to backfire going up gears and coming down gears. I then noticed that the nuts for my exhaust pipe were missing and the rear exhaust was off the head. I had these put back on and it seemed to lessen some of the backfire. I still have the back fire with acceleration. I am almost out of gas and am going to refill to see if i bought a bad or low octane tank of gas. I have also blew the dirt out of my air filter which i thought was to be a K&N but it has the harley logo so i dont think it is. I also pulled both spark plugs and found them to have a lot of black on both so i cleaned them the best i could with some sand paper for now since i was at work when i did all this. Does anyone have any ideas or can tell me if i might have ruined something with the pipe off for the week or so until i found that problem.

thank you
bob

Aug 11, 2006 | 11:11 AM

Thumper26

Outstanding HDF Member

Joined: May 2005

Posts: 3,146

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From: A barrier island in NJ

RE: backfire problem

You raise a very good question. These bikes come running lean from the factory to meet EPA standards. The exhaust is quite restrictive and produces some strong back pressure to try and counteract the lean condition. That being said, I don't think a loose exhaust would hurt you because people put less restrictive pipes on all the time without rejetting. In other words, I doubt that you've ruined anything. What's confusing to me is that your plug readings would lead me to believe you may be running a little rich, and yet that should not be the case with no jet change and a loose exhaust. I would expect to see indications of a lean running condition. Make sure all exhaust gaskets are seated properly and that all of the bolts are torqued to spec and have blue Locktite on them where required. How many miles do you have on the bike? Have you had the 1K service done? Make sure the "play" on your primary chain is within spec. Some of the 05's also required a reflash to correct ignition timing. Ask your dealer if yours was one of those bikes and if the reflash was done. There is a way to tell by the number on the bottom of your seat, but I can't remember the particulars. Maybe a search in the tech section for the reflash on 05's will help you.

Other than the above, I'm at a loss to help you...

Good luck!

Aug 11, 2006 | 11:21 AM

axx6912

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Stage IV

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RE: backfire problem

ty. had the screaming eagle kit put on and was rejetted. I dont know about the reflash. i think i might be running rich because i can smell gas what appears to be out of the air cleaner.

Aug 11, 2006 | 11:52 AM

Thumper26

Outstanding HDF Member

Joined: May 2005

Posts: 3,146

Likes: 50

From: A barrier island in NJ

RE: backfire problem

Your plug color sure indicates a possible rich running condition. Here is a link to '04 and '05 carbed engines that might be worth looking at: https://www.hdforums.com/m_73069/tm.htm

I know there's more info on the reflash but I can't seem to locate it. You might also want to check the posts on this XLForum: http://www.xlforum.net/index.html

It's really bugging me that I can't find the reflash bulletin I read about a year ago!

Do you know what size jets were put in your bike? Maybe they went one or more sizes over what's required...

This is frustrating!

Aug 13, 2006 | 01:00 PM

axx6912

Thread Starter

Stage IV

Joined: Aug 2006

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RE: backfire problem

I changed spark plugs and it seemed to alleviate the backfire for about 10 miles and then it started again. Now when i went to start my bike yesterday morning i found another problem with my battery being loose and causing shutdown of my power. I had to charge my battery earlier in the year and must not have got it secured enough. Now this am i secured it and i did not seem to have the backfire problem. Could the battery have been rocking back and forth and striking the frame and causiong the backfire?

Aug 13, 2006 | 01:15 PM

Thumper26

Outstanding HDF Member

Joined: May 2005

Posts: 3,146

Likes: 50

From: A barrier island in NJ

RE: backfire problem

I guess theoretically, if the battery was shorting once in a while as it moved, it could cause no spark on a cycle that caught on another cycle and caused the backfire. BUT, then I'd have to wonder why I wasn't blowing fuses during the intermittent shorts!

Thumper26

Aug 16, 2006 | 07:49 AM

axx6912

Thread Starter

Stage IV

Joined: Aug 2006

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RE: backfire problem

took the bike to the guy that works on mine and he put a bigger jet in and it took my hesitation away and seemed to cure my backfire problems at the moment. the only thing that i didnt get was that he said my plugs were white when he took them out and when i took them out before that they were black. dont know.

thanks thumper.