SuzukiSavage.com - just another backfiring/carb question...

bobber_prjct_2010

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just another backfiring/carb question...
05/27/12 at 08:57:39

I have an '86 that until last Thursday had everything stock. I've never had any issues with backfiring on deceleration. Thursday was the day that I put a shorty muffler on. While it sounds amazing, I'm getting some significant backfiring. I wouldn't call it popping. It's quite obnoxious. I understand that some of it is normal, but would like to minimize the backfiring as much as possible. I've spent several hour researching carb specs, tuning, rejetting, etc and I was just hoping someone would be willing to confirm or reject my thought process. Keep in mind that I'm running stock airbox & filter. Oh, I've also installed the Verslavy cam chain adjuster mod.

1. Adjust idle mixture screw. If that doesn't help...
2. Increase Pilot Jet size. If that doesn't help...
3. Reduce spacer thickness of needle jet. If that doesn't help...
4. Increase main jet size.

Thanks in advance. Huh

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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28886 L.A. California Gender:	Re: just another backfiring/carb question... Reply #1 - 05/27/12 at 09:41:58 have you cleaned your TEV?
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Serowbot

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Re: just another backfiring/carb question...
Reply #2 - 05/27/12 at 10:03:16

Serowbot's carb tuning tips for beginners...

Quote:

A good indicator of overall jetting is the weather...if popping/backfiring increases on humid days, or at higher elevation, that indicates rich....less popping at those times indicates lean.

Drill out the brass plug on the idle mix screw... adjust for smooth and steady idle... if it needs more than 3 turns out, go one step larger on the pilot jet. The pilot jet will have an effect on MPG's... If you want good gas mileage, don't get carried away there...
CW, in, is going leaner,... CCW, out, is going richer...

The needle jet is adjusted by varying the spacer thickness under the plate that mounts the needle to the slide... this has the biggest effect on acceleration and in the midrange area... Say 60+ mph cruising, and half throttle acceleration...

To test the main, accelerate from 30 or 40 mph, in 4th or 5th gear at full throttle for several seconds, then reduce throttle by about 1/8,...if power increases for a second, you are lean on the main jet. Go up one jet size and test again.

Jets are incrementally additive.... starting with the idle mix, then pilot, then needle, then main... Each jet adds it's volume to the next in line... Wide open throttle is accessing all of them, so changes in one, adds to next and the next..
I start at the bottom, and work my way up.... idle, pilot, needle, then main...

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justin_o_guy2

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What happened?

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Re: just another backfiring/carb question...
Reply #3 - 05/27/12 at 10:11:06

Sounds to me like youre on the right track, But what do I know? I rode mine for 5 years always having to give it some choke to start & run for the first 5 minutes, no matter how hot it was, just cleaned the carb up & NOW it runs great, as soon as its started,, Yea NOW, Now that Im cleaning it up to sell it,,, Someone is gonna be very happy with this thing,,

I think it was the slide,, even tho I was careful, or thot I was, when I went in,, blast it all to heck innywaze!

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Serowbot YaBB Moderator ModSquad Offline OK.... so what's the speed of dark? Posts: 28657 Tucson Az Gender:	Re: just another backfiring/carb question... Reply #4 - 05/27/12 at 10:23:59 JOG... you should keep it... ...
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bobber_prjct_2010 YaBB Newbies Offline SuzukiSavage.com Rocks! Posts: 41	Re: just another backfiring/carb question... Reply #5 - 05/27/12 at 10:29:31 verslagen1 wrote on 05/27/12 at 09:41:58: have you cleaned your TEV? I haven't messed with the TEV yet. I'm a little hesitant the cut 10mm of the #35 spring. It sounded as if there were mixed reviews of doing that. either way, I need to get into the carb and do some cleaning. Thanks.
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bobber_prjct_2010

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Re: just another backfiring/carb question...
Reply #6 - 05/27/12 at 10:32:49

Serowbot wrote on 05/27/12 at 10:23:59:

JOG... you should keep it... Wink

...

I agree with Serowbot! Keep the dang thing!

Side note, I usually only have to keep the choke in for a minute when it's rather cold out. However, I'm in the midwest and it's hotter than heck right now. I haven't had to choke it for a few weeks on startup. It's been running like a dream, just got the backfire issue now with the new pipe.

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bobber_prjct_2010

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Re: just another backfiring/carb question...
Reply #7 - 05/27/12 at 10:35:38

bobber_prjct_2010 wrote on 05/27/12 at 10:32:49:

Serowbot wrote on 05/27/12 at 10:23:59:

JOG... you should keep it... Wink

...

I agree with Serowbot! Keep the dang thing!

Side note, I usually only have to keep the choke in for a minute when it's rather cold out. However, I'm in the midwest and it's hotter than heck right now. I haven't had to choke it for a few weeks on startup. It's been running like a dream, just got the backfire issue now with the new pipe.

Can't type today....meant to say "I usually only have to give it some choke for a minute.."

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MarkHB Junior Member Offline Go for it! Posts: 88 Ottawa, Canada Gender:	Re: just another backfiring/carb question... Reply #8 - 05/27/12 at 18:55:26 Once I cleaned my TEV as vers suggests, all but the odd backfires disappeared. Don't cut the spring, just try cleaning the TEV first.
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verslagen1

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Re: just another backfiring/carb question...
Reply #9 - 05/27/12 at 19:13:01

bobber_prjct_2010 wrote on 05/27/12 at 10:29:31:

verslagen1 wrote on 05/27/12 at 09:41:58:

have you cleaned your TEV?

I haven't messed with the TEV yet. I'm a little hesitant the cut 10mm of the #35 spring. It sounded as if there were mixed reviews of doing that. either way, I need to get into the carb and do some cleaning. Thanks.

i wouldn't recommend you cut it. if you think that would help get the alternate springs they spoke about. you can try them and if they don't work, you always have the original to go back to.

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bobber_prjct_2010

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Re: just another backfiring/carb question...
Reply #10 - 05/28/12 at 07:46:24

verslagen1 wrote on 05/27/12 at 19:13:01:

bobber_prjct_2010 wrote on 05/27/12 at 10:29:31:

verslagen1 wrote on 05/27/12 at 09:41:58:

have you cleaned your TEV?

I haven't messed with the TEV yet. I'm a little hesitant the cut 10mm of the #35 spring. It sounded as if there were mixed reviews of doing that. either way, I need to get into the carb and do some cleaning. Thanks.

i wouldn't recommend you cut it. if you think that would help get the alternate springs they spoke about. you can try them and if they don't work, you always have the original to go back to.

Thanks

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rodeoclown Junior Member Offline SuzukiSavage.com Rocks! Posts: 66 Glenview,Il	Re: just another backfiring/carb question... Reply #11 - 06/03/12 at 07:45:04 Can you just take the TEV off while the carb is still on the bike or do you have to tear the whole carb down.
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ralfyguy Serious Thumper Offline Posts: 932	Re: just another backfiring/carb question... Reply #12 - 06/03/12 at 07:55:08 You can take it off while on the bike. Three screws, but take just two off first and then hold down the lid with one hand while removing the third and then release slowly as the spring will blow the lid in your face when it comes apart.
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