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Problems with backfiring

4K views 5 replies 3 participants last post by  linerdave 
#1 ·
Hi all, I just found this site and joined to hopefully solve a BIG problem. I bought an '08 RoadStar 1700 last August, it ran beautifully until the day before elections in November. It was put away for the winter, and got it out about 3 weeks ago when it started warming up again. First, my husband bought Cobra Slip-On Pipes, at that point it started backfiring and shooting flames out the pipes. After using these for about 1 month or so, he decided he wanted a little louder pipes and bought Vance and Hines Short Shots and had the dealer install them, along with a Power Commander box that he was told was needed. It's still running badly, and when the engine is cold, it has actually stalled out on him. We had it put on a Dyno last week by an authorized dealer, he found that the dealer had set the gas/air ratio way off, and he custom mapped it to where it should be. Still having the same problem. A friend of ours says his bike was doing the same thing, and it was fouled out spark plug(s). My husband was able to get to one of the 4 plugs, on examination, it looks black and charred. Can someone tell me how to get at the other 3 plugs to check them and probably change them without going back to the dealer AGAIN??
 
#4 ·
Sounds like the setup is way to rich. Backfiring out the tailpipe is a sign of excessive fuel.
 
#5 ·
That's what we thought, but the dyno has it mapped to what it should be running at. At first when it was put on the dyno, the dealer we bought the bike from had the ratio at 25:1 not using a dyno, and when it was put on the dyno and mapped out, he had to adjust it way down.
 
#6 ·
Fuel

FM23,
Don't rule out the problem being bad gas from setting all winter. Maybe try some carburetor / injector cleaner Maybe a half can in a full tank of premium gas. I like Sea Foam, at Wall Mart. If the problem persists then deal with it then. Maybe spark plugs first.

Dave
 
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