SuzukiSavage.com - Backfires & Afterfire reduced somewhat

JESPOKER4FUN

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Backfires & Afterfire reduced somewhat
03/13/10 at 21:39:31

Warning -- this one is not altogether panning out as the poster originally intended. Please read the entire thread before doing anything and please realize that your various mufflers/air filters/previous rejets may render this mod less than totally effective on your bike when it is done as stated.

AS SUCH, this thread must be considered a "development work in progress" at this point and it will be due for review again later on in 2012. If the method jells and gets generally successful, it will remain in Tech Section -- otherwise it will go back into RSD as it will not be a proven method.

Oldfeller

I am still seriously thinking about the carb kit from Lancer but wanted to let everyone know how to eliminate the backfires on decel and the infamous afterfire.
I recently installed the Dynojet stage 1 kit and the bike runs perfect throughout the throttle range but still had backfires. Tried to fine tune some more with very little backfires and 1 mild poof at shutdown.
Well I finally removed the air cut valve diaphram spring and noticed how stiff it was. I had an old MerCarb Accelerator Pump Kit - 3302-9046 (Mercruiser 2bbl carb) which I used the spring from. The stiffness of the spring is less than the stock spring. If you cannot get your hands on one of these springs you can remove 10mm from your stock spring and get the same results.
After replacing the spring I rode for about 30 minutes allowing the bike to warm up. No more backfires on decel. Shut the engine down and waited for the poof, NO POOF!!!!!
YEEHAAAA!

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« Last Edit: 07/11/12 at 22:45:17 by Oldfeller--FSO »

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Serowbot YaBB Moderator ModSquad Offline OK.... so what's the speed of dark? Posts: 28707 Tucson Az Gender:	Re: Backfires & Afterfire gone completely!!! Reply #1 - 03/14/10 at 09:31:42 We are talking about spring number 35,... not spring number 1.... Correct?...
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JESPOKER4FUN YaBB Newbies Offline SuzukiSavage.com Rocks! Posts: 30 Henderson, NV Gender:	Re: Backfires & Afterfire gone completely!!! Reply #2 - 03/14/10 at 09:57:35 Yes, spring #35 Allows the diaphram to move more freely less tension. This is a known problem on other bikes. Some have completely disabled the air cut valve but this was a very easy fix. I am checking to see if the spring I used is sold seperately from the accelerator kit. I will post when I find out.
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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28890 L.A. California Gender:	Re: Backfires & Afterfire gone completely!!! Reply #3 - 03/14/10 at 10:22:16 If you can measure the spring diameter, wire diameter, type of wire, number of coils, and type of ends then we can get springs out of any catalog.
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JESPOKER4FUN YaBB Newbies Offline SuzukiSavage.com Rocks! Posts: 30 Henderson, NV Gender:	Re: Backfires & Afterfire gone completely!!! Reply #4 - 03/14/10 at 10:54:16 This is the spring I used. The long spring. I will remove it and get all of the measurements.
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JESPOKER4FUN

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Re: Backfires & Afterfire gone completely!!!
Reply #5 - 03/15/10 at 18:50:28

Ok, here is the link to order the spring for the air-cut valve.
http://www.carburetion.com/r2.asp
Just scroll down to part# 66-15
.95 plus shipping

Inside dia. = .385
length = 1.580
wire dia. = .025
I just checked the shipping charge from this site. They charge shipping & handling.
Total for the spring will be about $12.00
I will also look for a different site.

You might want to search other sites

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Bubba

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Re: Backfires & Afterfire gone completely!!!
Reply #6 - 03/17/10 at 08:29:34

I'm interested in trying this. I'm running a pretty open pipe, stock everything else (except I'll probably rejet and get a K&N drop in air filter).
When you say, take 10mm off the stock spring do you mean 10 mm from the end of the wire or 10 mm from the overall length of the spring?
12 bucks for shipping is pretty steep. I wish there were a place called springs 'r us!

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'06 lt Blue, Dyna Power pipe, air screw 2 1/4 turns, 52.5 pilot w/ bleed holes, 150 Main, 2/3 spacer, Pirelli MT66 tires, Raptor petcock, 412-4006 Progressive shocks

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PipJones Full Member Offline Posts: 146 Fort Worth, Tx Gender:	Re: Backfires & Afterfire gone completely!!! Reply #7 - 03/17/10 at 08:53:00 i've got and extra spring for this carb and would like to try cutting some off. What was the length you said? 10MM from the end of the spring while compressed or wile relaxed???? ~Pip Jones
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qp YaBB Newbies Offline Posts: 26 Salt Lake City Gender:	Re: Backfires & Afterfire gone completely!!! Reply #8 - 03/17/10 at 09:14:42 Is there a gasket or gasket compound under the cover for spring 35?
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RadRacer

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Re: Backfires & Afterfire gone completely!!!
Reply #9 - 03/17/10 at 17:38:40

First off this definitely goes into the tech section and here...
......I have tried it all and have gotten rid of a majority of after fire running a 55 pilot 160 main, k&n cone filter, jardine exhaust and there was always a little left .. when i read this this morning before work that was all i thought about all day so when i got home grabbed a pair of dikes , Phillips screwdriver, and digital micrometer five minutes later i was done and took a test ride WOOOOOOW its finally gone WooooHoooo

Now to answer some of the other guys Questions

ther is no gasket but there is a diaphragm in there no need to pull it out or anything just remove 3 Philips screws and remove cover (CAREFUL) there is a spring pushing outward. once u have the spring in hand while its extended to where it sits on its own using micrometer pick an end and spiral it down the spring with one end of mic on end of spring other running down coil when u read 10mm snip it and reassemble with cut end out towards cover and your done

Thanks again Jes u are the man

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'97 Savage stock carb #55 pilot, 1/2 spacer, #160 main,Modified Jardine, K&n air filter w/ pre-charger wrap, Nology Ign. Coil, PowerStar Spark Plug, ported head, stock cam, Verslavvy,Belt Drive

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JohnBoy

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Re: Backfires & Afterfire gone completely!!!
Reply #10 - 03/17/10 at 20:42:04

A quick question here.
Is it possible that the spring is over long by design, to compensate for loss of tension over time?
If so, what symptoms would one see if the spring was no longer strong enough?
The replacement is easy and cheap enough to do often...but how often?

Great post Jes! This kind of brainstorming is why I read the post!
Thanks Suzuki! Where else can you have this much fun on a budget?
JB

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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28890 L.A. California Gender:	Re: Backfires & Afterfire gone completely!!! Reply #11 - 03/17/10 at 21:26:36 Look familiar? http://cgi.ebay.com/ebaymotors/Quadrajet-Carburetor-Accelerator-Pump-and-Retu... Got a mechanic buddy? ask him for all there left over carb springs.
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fascar228 YaBB Newbies Offline SuzukiSavage.com Rocks! Posts: 34 Islamabad Gender:	Re: Backfires & Afterfire gone completely!!! Reply #12 - 03/17/10 at 21:51:05 Hi All, I have done the hartman's mod to the muffler and the rest is stock, would this procedure also fix my bikes afterfires and back fires. In other words would this mod work on a stock machine????
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BurnPgh

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Re: Backfires & Afterfire gone completely!!!
Reply #13 - 03/17/10 at 22:08:47

It would work no problem, but i wouldnt suggest it as a replacement for proper jetting. From what I understand this mod to the "transient enrichment valve" allows a smoother fuel transition between throttle positions to help eliminate popping and "backfiring" on deceleration specifically.
Since you've got a free flowing muffler now you really need to rejet, or at least let us know what jets you have (since various international models have different jettings). Since you're in the middle east you might not have to change much being in such a warm area, but Id at least pull the spark plug and let us know how it looks and also take the carb apart and let us know whats pilot jet and main jet you have and what position the jet needle is at.

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JESPOKER4FUN YaBB Newbies Offline SuzukiSavage.com Rocks! Posts: 30 Henderson, NV Gender:	Re: Backfires & Afterfire gone completely!!! Reply #14 - 03/17/10 at 22:14:53 Glad to hear that some have tried this. I am sorry for not answering most of your questions, I have been very busy at work. Thanks for all of the replies. Jesse.
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