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/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Backfires & Afterfire reduced somewhat /cgi-bin/YaBB.pl?num=1268545171 Message started by JESPOKER4FUN on 03/13/10 at 21:39:31 |
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Title: Backfires & Afterfire reduced somewhat Post by JESPOKER4FUN on 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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Title: Re: Backfires & Afterfire gone completely!!! Post by Serowbot on 03/14/10 at 09:31:42 We are talking about spring number 35,... not spring number 1.... Correct?... http://personal.inet.fi/cool/alppu/bike/wt_2081.jpg |
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Title: Re: Backfires & Afterfire gone completely!!! Post by JESPOKER4FUN on 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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Title: Re: Backfires & Afterfire gone completely!!! Post by verslagen1 on 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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Title: Re: Backfires & Afterfire gone completely!!! Post by JESPOKER4FUN on 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. http://i1002.photobucket.com/albums/af141/JLSACESUP/carb%20parts/acceleratorpumpkit.gif |
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Title: Re: Backfires & Afterfire gone completely!!! Post by JESPOKER4FUN on 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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Title: Re: Backfires & Afterfire gone completely!!! Post by Bubba on 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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Title: Re: Backfires & Afterfire gone completely!!! Post by PipJones on 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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Title: Re: Backfires & Afterfire gone completely!!! Post by qp on 03/17/10 at 09:14:42 Is there a gasket or gasket compound under the cover for spring 35? |
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Title: Re: Backfires & Afterfire gone completely!!! Post by RadRacer on 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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Title: Re: Backfires & Afterfire gone completely!!! Post by JohnBoy on 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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Title: Re: Backfires & Afterfire gone completely!!! Post by verslagen1 on 03/17/10 at 21:26:36 Look familiar? http://cgi.ebay.com/ebaymotors/Quadrajet-Carburetor-Accelerator-Pump-and-Return-Spring_W0QQitemZ330398494702QQcmdZViewItemQQptZMotors_Car_Truck_Parts_Accessories?hash=item4ced48efee#ht_1079wt_857 Got a mechanic buddy? ask him for all there left over carb springs. |
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Title: Re: Backfires & Afterfire gone completely!!! Post by fascar228 on 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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Title: Re: Backfires & Afterfire gone completely!!! Post by BurnPgh on 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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Title: Re: Backfires & Afterfire gone completely!!! Post by JESPOKER4FUN on 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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Title: Re: Backfires & Afterfire gone completely!!! Post by kickstartmyheart on 03/22/10 at 12:40:34 this is awesome... i am running a very short straight pipe and i found that i was able to get ride of the backfires by changing my main jet to 160 andmy idle to 57.5 and turning out my air mixture screw 2.5 turns ... i am also using a k&n airfilter... so far i have no power loss good acceleration and people can hear me coming my bf can hear when i am speeding on the freeway..lol we live 8 blocks from the interstate but i am glad i was able to solve this problem... hopefully this might help for anyone else with a short pipe and backfiring issues |
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Title: Re: Backfires & Afterfire gone completely!!! Post by fire8310 on 06/10/11 at 17:14:51 kind of bringing this back from the dead...but this works like a charm. just did it today, and whalahh, no more back/after fire. |
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Title: Re: Backfires & Afterfire gone completely!!! Post by MotoBuddha on 06/17/11 at 07:05:49 272637353D372432560 wrote:
No. The lip of the diaphragm acts like a seal. Mine looked like this when I opened it up: http://i280.photobucket.com/albums/kk182/motobuddha/48dd2968.jpg http://i280.photobucket.com/albums/kk182/motobuddha/86375c50.jpg http://i280.photobucket.com/albums/kk182/motobuddha/50433d5a.jpg The crystalized fuel or whatever it is, plus the corroded part, aren't good. Probably a lot of sticking going on. But this carb started out like this, so I wasn't surprised: http://i280.photobucket.com/albums/kk182/motobuddha/8a893bb4.jpg |
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Title: Re: Backfires & Afterfire gone completely!!! Post by fire8310 on 06/17/11 at 07:31:08 ouch... that looks nasty..^^^ Webhead: I have the spring mod along with about half the spacer ground down. and it seems to work pretty good. definitely check for exhaust leaks. I have one with my recently installed dyna pipe because of the clamp im using. I have another clamp on the way along with some high temp gasket maker to fix that problem. Before i did the pipe swap this mod did away with my backfires though. now I have a little pop from what im assuming is the exhaust leak. or i hope so anyways. |
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Title: Re: Backfires & Afterfire gone completely!!! Post by TheSnakeLady on 06/19/11 at 12:44:01 I will be trying this mod as soon as I can get the screws out, gosh darn things are seized up (piece of crap carb screws)! So if anyone knows any tricks to un-seize screws please respond to this thread or pm me. I have an easy out kit but I'm trying to save the screws. Also I just want to get this straight, you take approx 10mm off the lengh of the spring wire, not 10mm off entire spring (I can't seem to find a good way to explain this). I was also just wondering if any of the senior members had tried this yet? :) |
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Title: Re: Backfires & Afterfire gone completely!!! Post by MotoBuddha on 06/19/11 at 13:21:58 342825332E212B252C212439400 wrote:
Try grabbing the heads from the side with pliers. |
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Title: Re: Backfires & Afterfire gone completely!!! Post by TheSnakeLady on 06/19/11 at 16:52:09 6D4F544F625544444841200 wrote:
Try grabbing the heads from the side with pliers.[/quote] I'll give that a try when I have some more time, the weather is supposed to be pretty nice for the next couple days sooo... this isn't something I'm gonna do till the weather turns crappy again. If all else fails I'll try vice grips. ;) Thanks for the advice man! |
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Title: Re: Backfires & Afterfire gone completely!!! Post by Bubba on 06/20/11 at 06:23:17 I tried this mod but it didn't work for me. I think I got the spring from Johnboy way back when. For me (living at a mile high) it made my bike run like a diesel. I must say the afterfire and pop went away but the resulting mixture gave me gobs of black smoke pouring out of my pipe and it felt as if there was less power. These bikes are tuned almost right in stock form for altitude. As far as my mods in my signature line they worked better for me but I could be the exception here. |
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Title: Re: Backfires & Afterfire gone completely!!! Post by fire8310 on 06/20/11 at 19:09:15 2E323F29343B313F363B3E235A0 wrote:
I took 10mm off of the entire thing. stood it up, used a fine measuring tool. and took off 10mm. Maybe I did it wrong. dunno. |
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Title: Re: Backfires & Afterfire gone completely!!! Post by Boule’tard on 06/21/11 at 09:08:04 574B46504D4248464F42475A230 wrote:
Have a look at Gyrobob's double Ryca build thread, he has a method of unsticking carb screws with gentle use of a center punch and hammer. I would have tried the spring shortening by now if I still had a BS40 carb. |
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Title: Re: Backfires & Afterfire gone completely!!! Post by jdeluca on 06/21/11 at 09:31:28 Honestly, mine were stuck and I just used a pair of channel locks, then took them to the hardware store and replaced with some good steel screws. The ones I got were a smidge long, so I got some lock washers as well. I believe they were M4's, there's a post somewhere that gives the correct screw types. |
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Title: Re: Backfires & Afterfire gone completely!!! Post by Gyrobob on 06/27/11 at 03:58:27 7E73697079687D6E781C0 wrote:
Thanks for the reference. Technically, though, I used a punch that was flat on the end, not a "center punch" that you'd use for punching a depression to start drilling a hole. The flat-ended punch works better because the only damage it does to the screw-head is to put a tiny little flat spot on it. http://i258.photobucket.com/albums/hh253/Gyrobob_theOriginal/Motorcycle/RYCA%20CS-1%20LS650%20S40%20Savage/LS650carb9Jun78Medium.jpg That said, just about anything you have around that'll serve the purpose will do. I've used a large nail with the pointy end ground flat. It has lots of advantages: real cheap, easy to make, soft material (less damage to parts of concern),.... and it makes a lovely Christmas gift. |
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Title: Re: Backfires & Afterfire gone completely!!! Post by Markusublime on 07/06/11 at 22:52:26 I've tried this mod on my bike and had no luck.I cut 10mm off the length of the factory spring,my backfires and "poof" are still there.I set up the mixture screw using the 5 gas analyzer at the shop I work at,but still to no avail.I have yet to try the spacer mod so I'm hoping that and some aftermarket parts and more tuning may help.I must admit though,like one of the other folks mentioned,I've grown fond of my "poof" also 8-) |
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Title: Re: Backfires & Afterfire gone completely!!! Post by arteacher on 09/24/11 at 13:18:22 I thought I would rejuvenate this thread: How many have tried it? Did it work? |
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Title: Re: Backfires & Afterfire gone completely!!! Post by TheSnakeLady on 09/24/11 at 14:14:18 I trimmed 10mm of the length of the spring (about half a spiral), it neither cut down on afterfires or backfires. Next step will be to cut 10mm off entire length but I'm hesitant... Riding season is almost over here in Central New York so I suppose now is the time, if it makes anything worse I can simply pack up the bike for the winter and order a new spring. |
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Title: Re: Backfires & Afterfire gone completely!!! Post by HJH on 09/24/11 at 14:49:39 I cut 10 mm off the total height of the spring, as instructed, and except when the bike is first started, I have no more backfires on deceleration or shifting, despite the fact I have not switched from the 52.5 pilot to the 55 because I am at 6,000 feet and need leaner jetting than most folks. No loss of power from the spring mod, and the addition of one more washer to go from 1/2 to 3/4 of the original spacer has made the bike run more cleanly, accelerate better and gas mileage is up, despite my driving style. |
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Title: Re: Backfires & Afterfire gone completely!!! Post by arteacher on 09/25/11 at 05:48:28 So far the score is: worked for 4 did not work for 2 :-/ |
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Title: Re: Backfires & Afterfire gone completely!!! Post by arteacher on 09/25/11 at 11:18:24 Make that 4 to 3- I tried it today and experienced a slight reduction in backfires but now my idle is uneven and I can't tune it properly. Guess I will have to order the spring from the stealer and "put 'em back the way they was" to quote "Li'l Abner". ;D |
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Title: Re: Backfires & Afterfire gone completely!!! Post by TheSnakeLady on 09/25/11 at 15:47:02 Art, have you done the spacer mod? I myself haven't but I noticed that at least one of the guys that this worked for had and it seemed, if I understood his post correctly, he may have needed to play with that mod along with this mod. Hmm, perhaps we should try that before going back to stock. :question |
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Title: Re: Backfires & Afterfire gone completely!!! Post by arteacher on 09/25/11 at 16:12:02 Yes I did a 2/3 spacer mod. And rejetted and I have a dial-a-jet as well. I pulled the plug a week ago and it looked pretty good, so I know I've got the jetting right. |
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Title: Re: Backfires & Afterfire gone completely!!! Post by danman1 on 09/28/11 at 02:49:40 im in southern ca. almost straight through pipe small baffle, running a 155 main and 55 pilot with a shaved in half white spacer and just cut down the 10mm off of the entire spring on the side of the carb. also i had to tighten my idle adjustment, the mod caused the bike to idle lower. the poof was very annoying before but now bike has a very silent unnoticeable poof at shutoff which is great. 8-) bike seems to backfire when revving engine past and around 2/3rds throttle with clutch pulled in now though. i only rode it for about ten minutes after the mod so ill get more info later. ill probably play with my air fuel mixture screw when the sun comes out. id say it worked for me. |
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Title: Re: Backfires & Afterfire gone completely!!! Post by danman1 on 09/29/11 at 16:13:35 the poof is back with a vengeance. i really dislike using that word "poof" when describing how my bike sounds. |
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Title: Re: Backfires & Afterfire gone completely!!! Post by Gyrobob on 09/30/11 at 10:30:30 5B5E51525E510E3F0 wrote:
I can understand your discomfort with the term "poof." Are you sure your throttle enrichment valve (TEV) is clean, clear, and working normally? See MotoBuddha's reply #20 in this thread. |
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Title: Re: Backfires & Afterfire gone completely!!! Post by danman1 on 10/05/11 at 14:54:29 since that post the after-fire is silent again. i guess it can return when it wants to. thats better than after-fire at every shutoff. though i should mention that two days ago i looked at the exhaust while i hit the kills-witch and a small burst of fire came shooting out, not any noise. i just looked at post #20 and my tev looked nothing like that. nor did my crab floats and bowl. :) that looked horrible. |
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Title: Re: Backfires & Afterfire gone completely!!! Post by arteacher on 10/06/11 at 16:58:42 I have been driving around with the cut spring for a week now, and the backfires are greatly reduced. The problem I am having is that when I come to a stop light and pull the clutch with the throttle off, it stalls sometimes, and when it doesn't stall the idle drops way down for a second before coming back up. And sometimes the idle is uneven. Is there a way to tune this out? I run a Raask exhaust, K&N drop in filter, 2/3 spacer mod, 55 pilot with bleed holes and a 150 main with a Dial-a-Jet. The mixture screw is 1 1/2 turns out, and the idle set to 1100 rpm. |
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Title: Re: Backfires & Afterfire gone completely!!! Post by danman1 on 10/06/11 at 18:44:33 ^mine also did that. so i raised the idle. but i dont have a tach so i dont know what its idling at. it sounds good though now. before i cut the spring it idled straight and constant like a lawnmower.. now it has a beat like an old chopper should. i like it. |
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Title: Re: Backfires & Afterfire gone completely!!! Post by arteacher on 10/07/11 at 16:13:12 I did some research and this valve is also called a coaster valve and is designed to enrich the mixture when coasting with the throttle off. So when you come to a stop and close the throttle the vacuum inlet on the engine side of the butterfly sucks the diaphragm out enriching the mixture. Cutting the spring makes it so less vacuum is needed to enrich the mixture. Which in turn rich-ens the idle. I much prefer not having to let the clutch out to restart the bike while coasting to a stop to having reduced backfire and pop. Sure you can set the idle to 1500 rpm to compensate, but I don't much like that idea either. |
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Title: Re: Backfires & Afterfire gone completely!!! Post by Oldfeller on 07/12/12 at 13:03:14 This tread is locked for additional comments. If you want to continue discussing this dead one, go here. http://suzukisavage.com/cgi-bin/YaBB.pl?num=1335447146 If you want to read the TEV-2 theoretical thread that replaced this one, go here. http://suzukisavage.com/cgi-bin/YaBB.pl?num=1318209614 |
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