SuzukiSavage.com - Backfire question

AZSGT Full Member Offline 2006 Bobber Posts: 132 Mesa, AZ Gender:	Backfire question 09/26/11 at 16:52:26 My bike never backfires, runs like a top. Except when I am on the freeway. If I am in 5th and moving at freeway speeds, not WOT but on it pretty good, when I roll off the throttle, the bike pops like crazy. Probably 6 or 8 times. I am not really concerned about it, I was just curious if anyone else has this, why, and what can I do about it?
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drums1 Serious Thumper Offline '87 Savage Bashed--Down for the count Posts: 664 Racine, Wisconsin Gender:	Re: Backfire question Reply #1 - 09/26/11 at 17:09:04 Mine does that some. Exhaust leaks will cause it.
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AZSGT Full Member Offline 2006 Bobber Posts: 132 Mesa, AZ Gender:	Re: Backfire question Reply #2 - 09/26/11 at 17:09:54 OK how come it only does it at high speed/high RPM?
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Oldfeller--FSO Serious Thumper ModSquad Offline Hobby is now "concentrated neuropany" Posts: 12671 Fayetteville, NC Gender:	Re: Backfire question Reply #3 - 09/26/11 at 18:07:51 After a full speed run your muffler internals are a dull glowing red .... Theory is that fresh air is back sucked into the short muffler by the back pulse (between the out pulses) and the fresh air ignites the fuel remnants in the normal exhaust flow .... .... providing things are hot enough to ignite it.
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AZSGT Full Member Offline 2006 Bobber Posts: 132 Mesa, AZ Gender:	Re: Backfire question Reply #4 - 09/26/11 at 19:49:37 HMMMM interesting. Like I said not anything I worry about, just curious and bored, making conversation.
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rl153 Serious Thumper Offline S40 Just right! Posts: 906 Bloomfield,CT Gender:	Re: Backfire question Reply #5 - 09/27/11 at 12:17:43 hows the air filter?
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Serowbot YaBB Moderator ModSquad Offline OK.... so what's the speed of dark? Posts: 28644 Tucson Az Gender:	Re: Backfire question Reply #6 - 09/27/11 at 12:29:15 Mine does the same thing.... I think it's just excess fuel igniting in the hot exhaust pipe... Best thing is to try not to do a full throttle chop when you decel.... ease the throttle down if you can...
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Gyrobob

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Re: Backfire question
Reply #7 - 09/27/11 at 12:46:12

AZSGT wrote on 09/26/11 at 16:52:26:

My bike never backfires, runs like a top.

Except when I am on the freeway. If I am in 5th and moving at freeway speeds, not WOT but on it pretty good, when I roll off the throttle, the bike pops like crazy. Probably 6 or 8 times. I am not really concerned about it, I was just curious if anyone else has this, why, and what can I do about it?

The transient enrichment valve exists to prevent this from happening. Maybe yours is sticking.

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If you think there's good in everyone, you haven't met everyone.

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Routy

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Re: Backfire question
Reply #8 - 09/27/11 at 13:29:04

Ok, it backfires,........
(call it any other sofistigated name you please)
now come a couple choices,.....one it to start hacking the carb and anything else you can think of, and probably end up making it worse than what it is, and for sure making it run, and idle worse,......or you can accept it as being the nature of the beast,........because thats what it is !
Now,.....should you decide to start hacking, (god forbid) the petcock is the most favorite place to start ! Roll Eyes

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Rich
'07 S40 Blvd stocker, except drilled OEM exhaust and white spacer mod...1/2 (.055)

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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28884 L.A. California Gender:	Re: Backfire question Reply #9 - 09/27/11 at 13:41:58 routy? you ok? you're going all billified on us.
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bill67 Serious Thumper Offline old tired Posts: 8517 genoa city wisconsin Gender:	Re: Backfire question Reply #10 - 09/27/11 at 15:41:53 The S40 carb will never work right unless its been taken apart 4 or 5 times.
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drums1

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Re: Backfire question
Reply #11 - 09/27/11 at 19:00:46

And then maybe not, if not assembled correctly. And then maybe not, still, if you have other issues.
Roll Eyes

Carb (float setting, needle and seat, transient enrichment valve, jetting, white spacer, slide issues, etc., etc.) Leaking exhaust, either at header, or any connection downstream. Petcock issues. Vacuum hose issues. Electrical issues. Bad gas or wrong gas issues. (Gyro?)

Personally I like that pop pop grumble pop on decel. Wakes the cagers around you up.

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royblueboy YaBB Newbies Offline SuzukiSavage.com Rocks! Posts: 48 Gender:	Re: Backfire question Reply #12 - 09/27/11 at 19:14:14 what is wrong with a little backfiring? i've always thought that is was normal for a 650.
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Gyrobob

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Re: Backfire question
Reply #13 - 09/27/11 at 19:41:31

drums1 wrote on 09/27/11 at 19:00:46:

And then maybe not, if not assembled correctly. And then maybe not, still, if you have other issues.
Roll Eyes

Carb (float setting, needle and seat, transient enrichment valve, jetting, white spacer, slide issues, etc., etc.) Leaking exhaust, either at header, or any connection downstream. Petcock issues. Vacuum hose issues. Electrical issues. Bad gas or wrong gas issues. (Gyro?)

Personally I like that pop pop grumble pop on decel. Wakes the cagers around you up.

My sentiments as well. Lots of things can contribute to the popping on decel. My suspicion is that the most common cause is that the bikes are jetted a bit lean from the factory, and when the TEV gets some wear on it or sits for a while without being ridden, the engine gets a leaner than comfy mixture given to it during hi rpm decel.

For a stock bike, use clean 87, install a paper fuel filter, and ride it often. Once you make any mods that affect engine tune, start studying up on jetting and the TEV.

And, forgive me Lord, I do sorta like (just a little) some gentle popping on decel. My first real motorcycle, a Ducati 250 Monza, used to do that, and I loved it. But!!,.. I was 16 at the time. I'm not supposed to like that anymore, being four times as old.

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« Last Edit: 09/28/11 at 09:02:49 by Gyrobob »

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Built2Last Serious Thumper Offline Tempt Fate Posts: 1447 FTF Gender:	Re: Backfire question Reply #14 - 09/28/11 at 04:54:58 Decel pops make you look cool and you get more babes that way. So does black smoke and fire shooting out of your muffler...
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