SuzukiSavage.com - low rpm backfiring

ech_S40

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low rpm backfiring
03/01/07 at 06:18:17

I am new here, and definantly new to working on bikes. I have an '06 S40, I have put on a Jardine slip-on and installed one of the Dynojet kits (DJ144 Jet) , but I still have backfires at about 1/4 throttle. From what I can gather, by reading several other threads, this is from too small a pilot jet or is this an issue where dropping the the white spacer down a notch will take care of this problem.

Any help I can get would be greatly appreciated.

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'06 S40, Jardine Slip-on muffler, K & N Filter, Suzuki Pillow Top Gel Seat, Dynajet Kit DJ144 Main/Fifth Notch from top on needle

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bholly12 Junior Member Offline I love YaBB 1G - SP1! Posts: 71 Starkville, MS Gender:	Re: low rpm backfiring Reply #1 - 03/01/07 at 08:39:03 I'd start with halving the existing spacer then adjusting stock pilot jet before replacing it. That oughta help out a lot. The main jet should probably go up to at least a 150 too. -Brad
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Savage_Rob Serious Thumper Alliance Member Offline Mechanically Inclined Amateur Posts: 6972 Texas (Dallas area) Gender:	Re: low rpm backfiring Reply #2 - 03/01/07 at 09:19:17 Also, whenever you make a change, follow the procedures outlined in the Lancer's Straight & Simple Carb Tuning thread in the Tech Ref forum.
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Dynobob Serious Thumper Offline 2003 LS650 (with Supertrapp) Posts: 634 Northern Virginia Gender:	Re: low rpm backfiring Reply #3 - 03/01/07 at 10:11:56 bholly12 wrote on 12/31/69 at 16:00:03: I'd start with halving the existing spacer then adjusting stock pilot jet before replacing it. No need to fool with the white spacer. Leave it full size and adjust the needle. Dynojet has an adjustable needle. If you want a richer midrange, raise the needle/lower the clip.
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bholly12 Junior Member Offline I love YaBB 1G - SP1! Posts: 71 Starkville, MS Gender:	Re: low rpm backfiring Reply #4 - 03/01/07 at 10:56:56 Oh yeah, duh Brad. Serves me right for reading too fast
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ech_S40 YaBB Newbies Offline Oh, I am keepin' it real! Posts: 5 West Virginia Gender:	Re: low rpm backfiring Reply #5 - 03/01/07 at 11:21:01 Thanks for the help! I guess what I will try to do is lower the clip on my needle and see if that richens everything out first. If that doesn't work then I will change the pilot jet.
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Savage_Rob Serious Thumper Alliance Member Offline Mechanically Inclined Amateur Posts: 6972 Texas (Dallas area) Gender:	Re: low rpm backfiring Reply #6 - 03/01/07 at 12:14:43 Those are two different things. The needle is your midrange while the pilot jet is the low end. You should try adjusting the pilot (idle mixture) screw (the one on the right under the brass plug) before replacing the jet entirely.
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georgekathe Ex Member	Re: low rpm backfiring Reply #7 - 03/01/07 at 13:55:44 luckily person who owned my bike before had drilled out the brass plug, but through reading on site advise caution when drilling it lest you drill into screw (you said you are new to working on bikes so assume you have not drilled a plug before)
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justin_o_guy Ex Member	Re: low rpm backfiring Reply #8 - 03/01/07 at 14:23:50 You can wrap electrical tape around the bit just over 1/8"th up so you don't go in too far.
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Savage_Greg Serious Thumper Alliance Member Offline Don't go around your ass to reach your elbow... Posts: 7844 SW Washington State Gender:	Re: low rpm backfiring Reply #9 - 03/01/07 at 21:08:55 If you have a sharp bit, you don't even have to push. Let the bit cut and you won't "plunge" into the screw.
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Brewbrother

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Re: low rpm backfiring
Reply #10 - 03/03/07 at 18:23:53

ech_S40 wrote on 12/31/69 at 16:00:03:

I am new here, and definantly new to working on bikes. I have an '06 S40, I have put on a Jardine slip-on and installed one of the Dynojet kits (DJ144 Jet) , but I still have backfires at about 1/4 throttle. From what I can gather, by reading several other threads, this is from too small a pilot jet or is this an issue where dropping the the white spacer down a notch will take care of this problem.

Any help I can get would be greatly appreciated.

exhaust and intake leaks can cause a backfire. check your connections.

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Opportunities multiply as they are seized.
No spacer,60 pilot jet, 155 main jet, plug door, sportster muffler, k&n drop in, iridium plug, brake pedal mod,de-badged, Dunlops, bullet turn signals.

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justin_o_guy

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Re: low rpm backfiring
Reply #11 - 03/03/07 at 21:02:02

Did you have the 1/4 throttle backfires before the Jardine went on? I found the header pipe clamp was loose as I installed the Supertrapp. Snugging that up is a real easy task. If it is leaking after it's tight that crush washer costs about $4.00. Did you wrestle hard & wiggle the header in the head? That might mash that crush washer.

Don't despair! Ther's only so many things it can be & they are all easy to mess with. It just takes some time & patience & the ability to describe the problem accurately. There are folks here who can help you out. Maybe after I get the cam chain done & finish the tuning I will be one of them..

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Savage_Rob Serious Thumper Alliance Member Offline Mechanically Inclined Amateur Posts: 6972 Texas (Dallas area) Gender:	Re: low rpm backfiring Reply #12 - 03/05/07 at 07:58:51 I'm a big fan of being very sure you have no exhaust leaks. That backfire plagued me while I tuned and retuned my carb several times. I got new gaskets for both ends of the header and the backfires stopped. Though I still get a minor chuff at shutdown, it's not very loud and only occasional.
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ech_S40 YaBB Newbies Offline Oh, I am keepin' it real! Posts: 5 West Virginia Gender:	Re: low rpm backfiring Reply #13 - 03/06/07 at 06:37:21 Thanks for all of the support. I am relatively sure that it is not an exhaust leak, when I put the Jardine on, I didn't loosen the header at all, and I used a new exhaust gasket. But just in case is there a way to check for exhaust leaks?
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ech_S40 YaBB Newbies Offline Oh, I am keepin' it real! Posts: 5 West Virginia Gender:	Re: low rpm backfiring Reply #14 - 03/07/07 at 04:35:20 Never mind the above post, I lowered the the clip on the needle to lower the spacer, and used Lancer's tuning thread as suggested and except for an occasional pop, my girl is running like a top. Now all I need is for it to stay above freezing and I will be ready to go!
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