SuzukiSavage.com - backfiring.....what can I do?

jsw1159

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backfiring.....what can I do?
07/23/09 at 19:01:36

Ok.... I have an "07" I swaped out stock muffler for a HD off sporster, I changed the white spacer with half the size, I also changed main to a 150 from stock 145, did nothing with pilot turn mixture screw out 1-1/2 to 2 turns out. My problem I'm still having and hope someone can help is I am still having alot of popping between shifting, and decel. Where should I go from here? Oh and I double checked no exhaust leaks....that I can detect.

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DrunkenDwarf Senior Member Offline Morning Zombie Posts: 325 Seattle, WA Gender:	Re: backfiring.....what can I do? Reply #1 - 07/23/09 at 19:57:37 That's about where I am currently. Does it backfire on shutdown? Make idle richer. (more turns out on screw or bigger pilot jet) Does it backfire on throttle close? Make mid richer. (less spacer or bigger main jet) Not professional advice, but that's what I've noticed. -D. Dwarf
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Boule’tard Serious Thumper ModSquad Offline Master of the Obvious Posts: 1620 Austin TX Gender:	Re: backfiring.....what can I do? Reply #2 - 07/23/09 at 20:33:23 You'd be surprised how much effect the fuel screw still has out to 3.5 turns. That's where I set mine (just to get it to shut up and quit scaring grannies, as much as I enjoy that) until I discovered a tiny exhaust leak. Once the leak was fixed, 2.5 turns was sufficient to silence the backfiring.
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Rocco Serious Thumper Offline addicted 2 riding TcB Posts: 1049 south florida Gender:	Re: backfiring.....what can I do? Reply #3 - 07/23/09 at 23:21:58 i honestly just turned my screw a little to the right to get a little more pow....i need help mentally i think lol
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odvelasc

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Re: backfiring.....what can I do?
Reply #4 - 07/24/09 at 04:55:32

Boule’tard wrote on 07/23/09 at 20:33:23:

You'd be surprised how much effect the fuel screw still has out to 3.5 turns. That's where I set mine (just to get it to shut up and quit scaring grannies, as much as I enjoy that) until I discovered a tiny exhaust leak. Once the leak was fixed, 2.5 turns was sufficient to silence the backfiring.

You are gonna lose the screw at 3.5 turns out man. The bike vibrate a lot in case you have not notices Wink

. You should go no more than 2.5 before changing jets to a higher one. JW, you must have a leak. Run your bike for a few km and then check your muffler. If it has started to blue then you have a leak. Bluejob should clean it, but you will have to re-seal that muff at the header. My understanding though is that stock in the U.S is 150 and most people go up to a 152.5. Mine was a 145 stock (dyno jet sizes) and went up to a 146. Only got some popping when it was not warmed up enough on colder days. I had air mixture out about 2.0 turn max.

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justin_o_guy2 Serious Thumper Offline What happened? Posts: 55279 East Texas, 1/2 dallas/la.	Re: backfiring.....what can I do? Reply #5 - 07/24/09 at 05:21:16 I would think that spring tension could be increased to keep the screw from backing out by adding a small spring. Maybe one from a ball point pen.
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Moofed Full Member Alliance Member Offline ...and the engine just gleams... Posts: 148 Bloomington, Indiana Gender:	Re: backfiring.....what can I do? Reply #6 - 07/24/09 at 06:42:13 The microfiche says it already has a spring behind the mixture screw. Just from looking at the diagram it seems you could file a bit off the tip of the screw if you really needed that extra turn of adjustment to the rich side.
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BurnPgh

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Re: backfiring.....what can I do?
Reply #7 - 07/27/09 at 22:27:48

Had my idle mix at 3-3.5 turns for over a year and it never budged. I dont advocate it necessarily but I didnt have any issue. You'd also be surprised how little changes and weather can effect the carb. Depending on conditions I get anywhere from a loud sharp bang to a mouse fart or no backfire at all. Funny thing is rainy and cold (lean/lean)is not too loud a bang, but warm and dry(rich/rich) is just straight loud. Rainy and warm(lean/rich), and dry and cold (rich/lean)I usually get little or nothing. Seems being a bit rich and a bit lean both cause the backfire. At least on my machine. Or I have an exhaust leak. Havent checked. 145 is stock for US Savages. Except Cali I think. Theirs is ridiculously small IIRC. 135 or something.

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Moofed

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Re: backfiring.....what can I do?
Reply #8 - 07/30/09 at 17:05:35

My idle screw get gummed up I think. It wouldn't turn easily and eventually the slot was destroyed. Maybe if they are super clean they can backout on you when past 3 turns.

I got a replacement, but haven't tried to put it in yet. I don't think I've seen a picture of one on here before, so I'm going to fix that now:

That's an odd looking screw. Huh

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Serowbot YaBB Moderator ModSquad Offline OK.... so what's the speed of dark? Posts: 28657 Tucson Az Gender:	Re: backfiring.....what can I do? Reply #9 - 07/30/09 at 17:15:30 Wow!,.. that's a big one!....
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Serowbot YaBB Moderator ModSquad Offline OK.... so what's the speed of dark? Posts: 28657 Tucson Az Gender:	Re: backfiring.....what can I do? Reply #10 - 07/30/09 at 17:16:34 jsw,.... Try raising your idle speed a hair...
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Bear

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Re: backfiring.....what can I do?
Reply #11 - 07/31/09 at 11:24:03

I am using a Harley Dyna muffler and have gone up one jet size in main and (non bleed) pilot. Did not touch idle screw. Using about 1/3 white washer. Runs great, no backfire. One additional thing that may have made a backfire difference. I drilled a 3/16 hole through the center of the muffler baffle. Didn't change sound too much and I think it vents out the gas that makes the BANG. Whatever, mine runs great with no backfire. I made a drill guide out of plastic pipe, so the bit would hit close to the center of the baffle. A bigger hole would just be noisy. This now is just right mellow rumble.

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