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I see a lot of people talking about back firing. Some talk about adjusting this and that, some removing pair valve. Does back firing hurt anything? I have a 04 vol and it has back fired since day one. I thought this was normal, since this is my first motorcycle. It really don't bother me, but if is going to do some damage maybe I need to have this looked at. It has just had its 4000 mile service done, no problems. Any information would be great.
 

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ncvolusia said:
I see a lot of people talking about back firing. Some talk about adjusting this and that, some removing pair valve. Does back firing hurt anything? I have a 04 vol and it has back fired since day one. I thought this was normal, since this is my first motorcycle. It really don't bother me, but if is going to do some damage maybe I need to have this looked at. It has just had its 4000 mile service done, no problems. Any information would be great.
Both Pre and Post-ignition is not good for the bike over time.

Disabled pair-valve is highly recommended. No reason to remove it, unless you enjoy working on the innards of the bike...
 

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Disabling the PAIR Valve is good fun but if the bike is truly backfiring (you hear a coughing sound at the air intake) you should have the bike looked at by a qualified mechanic (bike is probably still under warranty.)

If it is not really backfiring, this is deceleration popping and is normal for bikes with PAIR Valves.
 

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My 04 does it as well, but not all the time. She's like me, some days she's in a good mood and doesn't "back talk" at all. The days she's in a nasty mood I can count on her "fussing" occasionally. On those days I don't ask a whole lot of her and she settles down and enjoys the ride with me.

Go figure.

Belle
 

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Brownw3 said:
Disabling the PAIR Valve is good fun but if the bike is truly backfiring (you hear a coughing sound at the air intake) you should have the bike looked at by a qualified mechanic (bike is probably still under warranty.)

If it is not really backfiring, this is deceleration popping and is normal for bikes with PAIR Valves.

what's going on if you get a backfire from the air intake?....I've had that happen 2 times when it was REALLY hot out....It happened when I was coming to a stop (decelerating) and I just "goosed" the throttle for a second..only happened 2 times so I didn't think it was a big deal....anyone have any advice?

oh-my bike is stock with holes drilled into mickey.
 

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byteman said:
If it only happens occasionally, I wouldn't bee too concerned.

After rejetting, before she warms up if I pop the throttle I will get a carb backfire. If the choke is on - this doesn't happen.
I was just assuming that it had something to do with the fact that we are running lean because it's only happened on H O T days....what you described kind of confirms this, I would say.

thanks
 

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My 04' did the same thing. I took it back to the dealer and he knew exactly what was wrong. It needed a new, I think, Air pump. The backfiring stopped immediately and the bike runs better than ever. It was covered under warranty.
 

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Coastie said:
My 04' did the same thing. I took it back to the dealer and he knew exactly what was wrong. It needed a new, I think, Air pump. The backfiring stopped immediately and the bike runs better than ever. It was covered under warranty.
Not Air Pump - He replaced your Pair Valve. Most of us remove the Pair Valve because it effectively does nothing except cause problems...
 

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Well, on really hot days, your motorcyle runs a little leaner than on a "perfect day (65-75 degrees) I've always said just ride the bike stock or replace everything starting at the air intake. Drilling holes in stuff starts to create holes. If you remove your stock pipes are actually very small in diameter. Once you begin any mods, you start to get away from stock "running" and should rejet to balance what I like to call "the fuel air equation." I have completely re-done my air intake and exhaust and I never have sputters, whimpers, backfires or complaints.

There is no short-cut to doing it right and then running on a dyno to ensure everything is just so.
 

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Brownw3 said:
Well, on really hot days, your motorcyle runs a little leaner than on a "perfect day (65-75 degrees)
I hate to disagree, but I will...
On days that are more humid, or days that are hotter the air density is LOWER and so given the unchanged amount of fuel from the carb, there is MORE fuel in the mix and therefore the engine runs a little richer than on a "perfect" day.

Most, but not all fuel injection systems compensate for this.
 

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You're missing a part of the equation; work on it and then I guarantee you'll agree. I'll give you the rest of the answer later. By the by, we're only talking about carb-equipped, downdraft type (oops, I gave you a hint)
 

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05 c50 back fire in the carb runs like shit. Still havent found the issue cleand manifold fuel filter injectors no vacuume leaks did the pair valve thing new battery any ideas on what it may be?
 

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You're asking questions in a 16 year old thread. The only person who is still active is Bill, but he has some cognitive issues and started buying Harleys....
 

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If it backfires on deceleration, you are likely getting an imbalance of air and fuel in the exhaust. My 98 LC was pretty good at backfire on deceleration as the previous owner had the carbs re-jetted. The bike was running rich. The unburnt gas gets in the exhaust and the pair valve opens on deceleration to let air in to burn the gasoline fumes. Lots of fumes means backfire. I disabled the pair valve with 2 golf tees, and no more backfire. Although the bike still runs rich and the unburnt gasoline fumes are just pushed out of the pipes. Sometime in the not too distant future I will return the carbs to stock as the re-jetting (feeble stage 1) is nothing to brag about.
 
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