|
SuzukiSavage.com
/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Next step in trying to eliminate backfiring? /cgi-bin/YaBB.pl?num=1353340744 Message started by David Bookbinder on 11/19/12 at 07:59:04 |
|
Title: Next step in trying to eliminate backfiring? Post by David Bookbinder on 11/19/12 at 07:59:04 I've read many posts on tuning the carb on the S40 to eliminate backfiring. As my carb had a stripped idle mix screw thanks to the previous owner's attempts to adjust it, I had the local shop drill it out and, as I also had a jet kit, asked them to rejet to eliminate backfiring. I am trying to find out exactly what they did, but from the writeup it looks as if they replaced the pilot jet with one size up and adjusted the idle mix. The bike still backfires. Less often, but still almost every time I either snap the throttle off at any speed or roll it down or off from high speed (as when preparing to exit the highway or stop at a stop sign). What's the most reasonable next step to try in order to eliminate backfiring? It now seems to occur only when the throttle is at about 25% or below. There should be no exhaust leak, as they also replaced a leaking head plug at the same time the rejetted the carb. Their claim is it will continue to backfire unless I install a less restrictive exhaust, but I'd like to keep the bike stock. Thanks, David |
|
Title: Re: Next step in trying to eliminate backfiring? Post by justin_o_guy2 on 11/19/12 at 08:25:27 I dont have the answer, but I would surely be interested to know what you paid for the screw extraction & then for the jetting. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by David Bookbinder on 11/19/12 at 08:32:16 More than I wanted to (I think it was $150, but I don't have the receipt handy) but less than the cost of a new carb. I was not confident I could drill the screw out myself without wrecking the carb, nor was I confident I could get the carb bottom off without stripping the screw heads. The carb had not been disassembled before. Now that it's already been taken apart and put back together, it should be safe for me to further tinker with it myself as needed. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by Serowbot on 11/19/12 at 08:47:33 Are these backfires you are getting,.. pops and blats,.. or very loud gunshot type cracks?... Pops and blats,.. are normal for a big thumper on decel... especially in cold or humid conditions... Speaking of which,... do they increase or decrease on humid days?... |
|
Title: Re: Next step in trying to eliminate backfiring? Post by David Bookbinder on 11/19/12 at 09:31:09 Gunshots. Haven't noticed a significant change when the humidity changes. Should I have? |
|
Title: Re: Next step in trying to eliminate backfiring? Post by verslagen1 on 11/19/12 at 09:40:46 shift pows are usually leaky header or muffler joints. use a lit candle to detect a leak second, clean your TEV. http://suzukisavage.com/cgi-bin/YaBB.pl?num=1267767908 |
|
Title: Re: Next step in trying to eliminate backfiring? Post by Serowbot on 11/19/12 at 09:42:38 If backfires get worse on humid days, or when riding in the mountains it indicates that you are on the rich side... If backfires are reduced,.. you are lean... Either, will cause backfires and popping... Constant backfires in all conditions usually indicates an exhaust leak... Some locations have very little variance... Where are you located?... |
|
Title: Re: Next step in trying to eliminate backfiring? Post by David Bookbinder on 11/19/12 at 09:58:21 There's no exhaust leak I or the shop that fixed the head plug leak can detect. It seems related to the pilot circuit. The mechanic, it turns out, didn't replace the pilot jet due to fear I'd foul plugs if I ran too rich with a stock muffler and air box. Have any of you found that going up a size in the pilot jet fouls plugs. I'm north of Boston, at sea level. Do lower elevations lean out the mix due to denser air? |
|
Title: Re: Next step in trying to eliminate backfiring? Post by Serowbot on 11/19/12 at 10:12:33 20262B2B2F262D2A202136440 wrote:
Yes, it do... A bigger pilot might help... if adjusting idle mix to 3 turns out don't do it,.. you might try a step larger on the pilot... Also, make sure that you idle speed isn't too low... but, I'm assuming that's okay because the dealer set it for you... |
|
Title: Re: Next step in trying to eliminate backfiring? Post by justin_o_guy2 on 11/19/12 at 18:43:31 but, I'm assuming that's okay because the dealer set it for you... Dealer adjustments are as suspect as any, IMO. How many oil filters have been put in bakkerds at a dealership? |
|
Title: Re: Next step in trying to eliminate backfiring? Post by Serowbot on 11/19/12 at 21:42:16 Too true... :-?... |
|
Title: Re: Next step in trying to eliminate backfiring? Post by denistheruski on 11/20/12 at 05:45:39 Serowbot, you're always telling folks to check their idle speed. I know that the oil pump needs ~1200 RPM to work properly. Are there other reasons idle speed is important? (I realize that pumping oil to critical engine parts is a very important reason ... I'm just curious if idle speed relates to backfiring somehow.) Also - is there an easy way to check RPMs without having a tach installed? |
|
Title: Re: Next step in trying to eliminate backfiring? Post by Charon on 11/20/12 at 06:13:46 Aside from making sure there is adequate oil pressure to the cam bearings, a higher idle speed will reduce the afterfiring and any tendency the bike has to stall when you come to a quick stop. You can prove it to yourself by closing the throttle slowly and perhaps not quite completely on deceleration instead of snapping it shut. Ever hear of anyone complaining about the afterfiring except when they are decelerating from speed with the throttle completely shut? |
|
Title: Re: Next step in trying to eliminate backfiring? Post by verslagen1 on 11/20/12 at 08:05:04 35343F38222539342324223A38510 wrote:
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1303712067 |
|
Title: Re: Next step in trying to eliminate backfiring? Post by David Bookbinder on 11/24/12 at 11:59:00 So... verified that the pilot jet was upsized to a 55 from a 52.5 and that the TEV is working fine. But, the bike still backfires, generally a loud gunshot crack but sometimes two quieter ones, as I'm decelerating and get below about 25% throttle. Opening up the idle mix screw another half turn dropped the idle speed and made the bike feel a little boggy, while only very slightly reducing the backfiring. Any other modifications I could try, from a carburetor point of view, that have been shown to fix this problem? I did look at the "trim the TEV spring" thread, but it seems the results there were inconclusive. Would drilling out the muffler have any effect on backfiring? I'm not interested in doing a muffler replacement at this time, and I don't particularly want to make the bike any louder, but I'd trade some increased volume for fewer backfires. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by verslagen1 on 11/24/12 at 12:34:22 If you're sure that your header and muffler are sealed up tight... and your carb is as clean as a whistle... I'd mod the TEV spring, but NOT the stock one. find yourself a couple that are close to it, length, number of coils, wire size, diameter. Note: more coils make it softer, less stiffer. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by David Bookbinder on 11/24/12 at 12:57:53 Well, I am sure there is no exhaust leak and that the carb is clean. I have an older carb lying around that I got on eBay to experiment with (and for spare parts in case I messed something up). I can take a look at that spring and see if I can modify it. Would cutting a coil or two off of it be the way to go, assuming that spring is the same as the one on my bike? |
|
Title: Re: Next step in trying to eliminate backfiring? Post by LANCER on 11/24/12 at 16:46:42 When tuning the screw you want the point of highest rpm. Turn the screw right and then left until you find the point of the highest rpm...that is the BEST setting for the screw. I find it odd that a #55 pilot jet works best on a stock engine with a totally stock exhaust. How many turns out are you on the pilot screw ? |
|
Title: Re: Next step in trying to eliminate backfiring? Post by David Bookbinder on 11/24/12 at 16:58:18 What's odd about the 55 jet on a stock bike? I had gone out to 3 turns on the idle mix screw with the stock pilot jet and I was still getting a lot of backfiring. Now, with the 55 jet, the idle mix screw is about 1 1/4 turns out. Unfortunately, still backfiring. Tried the 55 jet when it turned out the TEV was fine. Going up on the jet was an attempt to increase the richness of the mix to stop the backfiring, since I couldn't go out any further on the idle mix screw and make any difference. I'll try tinkering with it a bit more, but 1 1/4 turns seemed to give the best idle speed today (at about 45 degrees outside, sea level). Have people here been successful at eliminating backfiring on this bike with stock air box and exhaust? |
|
Title: Re: Next step in trying to eliminate backfiring? Post by Routy on 11/24/12 at 19:36:07 Quote: Have people here been successful at eliminating backfiring on this bike with stock air box and exhaust? --------------------------------------------------------------------- Best answer,....No,. stock or otherwise. Another answer,.....yes, till it came back. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by justin_o_guy2 on 11/24/12 at 19:40:50 Controlling it, getting it down to what an engine like this is really gonna do,, solving air leaks, getting the jetting right, its no longer obnoxious,, now, it growls & snarls as I downshift,, but it no longer is an embarrassment, it doesnt sound like a gun at every shift,, & the spittin & snarlin as it slows can be controlled, I just dont, cuz I LIKe It |
|
Title: Re: Next step in trying to eliminate backfiring? Post by David Bookbinder on 11/24/12 at 20:05:20 So, altogether, what modifications did you make to the stock bike in order to reduce the backfiring? |
|
Title: Re: Next step in trying to eliminate backfiring? Post by justin_o_guy2 on 11/24/12 at 20:23:16 The Big One was gettin the header pipe snugged up in the jug, I Think,., I pretty much hadda richen it up, cuz I put the Supertrapp on, w/ 14 disks, but, I cant remember what jets I used.Adjusted the Idle Air mix & I sanded the spacer down a bit on the needle. K&N drop in air filter., Before I did all that I went riding with 3 others.. None of them appreciated my bike,, it was just an embarrassing bunch of noise,,KInda helped me wanna work on it.. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by David Bookbinder on 11/24/12 at 20:28:34 So it still backfires even with the richer jets, Supertrapp, and spacer mod? Interesting. The mechanic I've been working with keeps trying to convince me the Supertrapp will fix that problem and in general make the ride much better. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by verslagen1 on 11/24/12 at 20:35:49 You can add disks to the supertrapp to let it breathe better, but it will lean it out, so you need to rejet. for stock jetting 6 to 8 disks are required. after you fix the air leaks, and tune it properly, all you'll get is grumble pops on decel, much like a jake brake on a truck. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by justin_o_guy2 on 11/24/12 at 21:29:29 I dont understand the whole OMG it Backfired mentality.. There is a situation where its just constant & annoying & uncontrollable & then theres a well tuned engine that Will growl & Spit. A leaky exhaust is Not Gonna Stop popping & banging between shifts & slowing down, poorly jetted engines make a racket thats tiresome,, a well tuned engine Still makes noise,, & Thank GOD for it.,Its a beautiful sound, coming down from a high speed run, racking the RPM up, synching the tranny up for the next downshift & series of Blapp Blapp groowwll sounds. Now, IF thats not okay, say, close to a nursing home or trying to sneak in the back door too late,,, then dont ride it like that, but before I did the work, I couldnt stand it, Im sure it was just leaks,, theyll make a mess of it.,. Okay? That splain it?> |
|
Title: Re: Next step in trying to eliminate backfiring? Post by LANCER on 11/25/12 at 03:40:55 7C7A7777737A71767C7D6A180 wrote:
What's odd is that a stock engine with stock exhaust just does not need need more than the 52.5 pilot. I have a 2006 with stock engine and header with just a muffler change, and it is a pretty open muffler. I have the 52.5 pilot set at 2 3/4 turns out and it is nearly backfire free. I had no backfires at all initially but the exhaust has since loosened a bit from the quick install I did so I need to go back and tighten it up. Point is that the 52.5 is just about all it needs. It is borderline but it is darn close. A stock engine with stock muffler will not move as much air and so will not need as much fuel. Since your stocker is still backfiring then there is another issue that is affecting the engine and making it backfire. Typically, an air leak in the head/header and/or the header/muffler connections is the other cause of backfiring. You said you were adjusting the pilot screw to reduce the backfire. That is a secondary but desirable effect of the tuning process. When you are tuning the pilot screw your goal is to achieve the best (highest) rpm when the COMPLETELY WARMED UP engine is idling. When you find that point, if you turn the screw either left or right the rpm will decrease. Then you know you have found the best setting. With that setting, adding no more than maybe a quarter turn for a dash of extra fuel to help that last little bit for any backfire left over. At this point you should be at least 95% backfire free, with only a rare shot...if not totally free. I would not expect a stock engine with stock exhaust to go beyond 2 turns out on a 52.5 pilot. With your situation where you have a 55 pilot and still experiencing backfire, there is an air leak somewhere. I would bet your exhaust is messing with you or perhaps there may be an air leak between carb, mounting flange & head as well. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by LANCER on 11/25/12 at 03:44:26 One add on; this assumes that your carb is functioning perfectly. If any of the passageways are clogged even a little bit that will affect it's function and mess with your jetting and tuning efforts. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by justin_o_guy2 on 11/25/12 at 06:31:36 affect it's function and mess with your jetting and tuning efforts. Mess with being the mildest of terms applicable..yea, I totally forgot to include that part..A clean & properly functioning carb is just something I figure folks have, & I need to rethink that,, its just not always so.. I gotta get in mine & have a look at the jets, but I Think Im gonna do that after I do the Raptured petcock,my stocker is gonna go meet God, in the air,, |
|
Title: Re: Next step in trying to eliminate backfiring? Post by David Bookbinder on 11/25/12 at 07:57:42 7B76797472652520170 wrote:
As far as I and the mechanic who took the carb apart and rejetted it can see, the carb is functioning perfectly, the exhaust is tight, the carb is installed properly, etc. They had to do the head plug leak fix and have been into the carb twice and can't find any problems, yet it still backfires even with the larger pilot jet. Their contention is that these bikes backfire due to being large, single cylindar bikes, but that installing a less restrictive exhaust such as the Supertrapp will probably eliminate the backfiring. This is more money than I want to put into a bike I will probably sell next year, so I'm looking for another solution. Pops and grumbles on decel I don't care about, but these are gunshot pops that frequently occur on decel once the revs go down significantly, though not on shifting. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by Charon on 11/25/12 at 09:01:19 Just for additional information: I used to have a 1983 Suzuki GR650 Tempter. It "backfired" and popped just like the Savage/S40. But it wasn't a thumper - it was a twin. The dealership "adjusted" it to eliminate the afterfire, but was unsuccessful. I mention this only to point out that it isn't only Suzuki's singles that afterfire. The most successful solution I have found is also the simplest: earplugs. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by LANCER on 11/26/12 at 03:55:35 Your carb has been apart twice by the mechanic and it looked good to him, but did he run the carb cleaning tool through all the jets and every passageway ? The carb cleaning tool is a little kit if speciality wires made for the very purpose of running through jets and passageways, which at times is the only way of clearing them of built up carbon, grit and fuel residue. There is no way to eyeball those passageways, you must run them with the wire. If your mechanic did not do that then he did not complete the job of cleaning the carb. It is a fallacy that a big single is destined to backfire simply because it is a big single. Do you think the owner of a BMW 650 would be satisfied with that answer from a dealer ? Or KTM or Honda 650 owner ? Nope. They do have fuel infection systems but that is just a better version of a basic carb. If their FI system malfunctioned do you think they would backfire ? Yep. And would the dealer simply pass it off as "it is just the nature of a big single" ? Not if they want to keep their business. They would fix it. We are such a small portion of the market that many Suzuki dealers just blow us off because they do not care or because their mech's no longer know how a carb works and how to fix them. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by David Bookbinder on 11/26/12 at 05:11:36 Thanks. I don't know if the mechanic at the dealership actually cleaned the TEV or just eyeballed it. I'll get a carb cleaning tool (there's a link here somewhere) and when I have had more practice with carbs (by cleaning the spare carb I have), I'll tackle this one and see if I can resolve the issue by cleaning the carb as you suggest. If not, then at least I know it's not the carb. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by Gyrobob on 11/26/12 at 05:46:15 535558585C555E59535245370 wrote:
While you have the carb apart on the bench, keep everything on a perfectly clean surface,... pretend you are doing brain surgery or something. -- I used to use a towel, but a t-shirt works better because t-shirt material has very little lint compared to terry cloth. One bit of lint trapped in a jet will add a lot of frustration. -- Doing everything on a large cloth also helps to keep small pieces in front of you, rather than bouncing and rolling into black holes, never to be seen again. Another way to get inner surfaces of complicated mechanical devices (carbs, for example) clean internally is to do it ultrasonically. These gadgets are cheap now, and can be used for all kinds of things besides carbs. I use mine for cartridges cases, gun parts, jewelry, dirty switches, piles of small fasteners, glasses, etc. Here's a newer version of the one I bought a long time ago, and it is on sale at the moment: http://www.harborfreight.com/25-liter-ultrasonic-cleaner-95563.html |
|
Title: Re: Next step in trying to eliminate backfiring? Post by justin_o_guy2 on 11/26/12 at 05:51:03 They'll knock a kidney stone out of a Guinea Pig, |
|
Title: Re: Next step in trying to eliminate backfiring? Post by Gyrobob on 11/26/12 at 05:57:50 3A37383533246461560 wrote:
Exactly. Every cylinder on every motorcycle of any type ridden by those viewing this discourse has a carb, cylinder head, exhaust header, and muffler. (this statement excludes FI systems) -- Single, twin, triple, four, or six cylinders makes no diff. -- It's just more noticeable on an LS650 because of the size of of the cylinder involved, and, since it has but a single cylinder, the burbles and pops seem more dramatic because of the time between exhaust pulses. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by Routy on 11/26/12 at 06:25:25 Heres a prediction,.......... You are going to keep messin w/ that carb....that there isn't anything wrong w/ untill you get it so screwed up you will end up forced to buy a new one. Many have ! If you can't simply learn to control backfire w/ the throttle, you have the wrong motorcycle,.....believe it ! |
|
Title: Re: Next step in trying to eliminate backfiring? Post by Charon on 11/26/12 at 06:48:25 This might be slightly off-topic, but it involves a single and afterfiring. I have a Yamaha Majesty scooter, 400 cc single, fuel injected. When I took it to the Rocky Mountain Park earlier this year, I noticed at high altitude it also would afterfire and "grumble" on deceleration. I didn't happen to notice the altitude at which it started happening, but I am guessing above 8000 feet. I started browsing through its service manual, and it has an air injection system which injects air into the exhaust very near the engine any time the pressure in the exhaust goes negative (below ambient) with the idea of burning any unburnt hydrocarbons in the exhaust. I can only speculate that at high altitude the pressure differences were small enough the air injection didn't work, and the resultant unburned stuff could afterfire. The LS650 has no such injection system (and if it did folks would complain and remove it), so has no way to avoid the afterfire. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by LANCER on 11/27/12 at 04:02:22 04020F0F0B02090E040512600 wrote:
The carb cleaning wire tool is available from Sudco (323-728-5407) part #950-203 for $10.50 |
|
Title: Re: Next step in trying to eliminate backfiring? Post by David Bookbinder on 11/27/12 at 07:13:42 Quote:
Thanks! |
|
Title: Re: Next step in trying to eliminate backfiring? Post by David Bookbinder on 11/27/12 at 07:15:18 414E544F535546444C4255270 wrote:
That's why I got a spare carb to experiment with, so I know what I'm doing when I open up the "real" carb which, since it's been taken apart and put back together by the shop, should not be hard to dissassemble and reassemble. If I know it's fine, then I'll learn to live with the backfring, but at the moment I don't know that. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by justin_o_guy2 on 11/27/12 at 09:31:52 Man,, I wanna see the tool, but IM not loadin that whole catalog over it.. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by verslagen1 on 11/27/12 at 09:56:43 K&L carb cleaner wire set http://www.who-sells-it.com/images/catalogs/4490/21721/ct/normal_model-replacement-and-performance-parts-no-35-000252.jpg |
|
Title: Re: Next step in trying to eliminate backfiring? Post by justin_o_guy2 on 11/27/12 at 11:15:19 KInda sorta looks like a cuttin torch tool. I have a selection of fine wire, NO, Not Wine, Wire,, & can generally find what I need just layin in the shop, on a shelf, by the radio. Some are pointed, some blunt. A trip to the hobby shop for what they call Control Rod , or PIano Wire,, Great stuff, so hard it can break if bent too far too quickly, & heating it & letting it cool slowly only makes it more brittle,, I havent tried a quench to anneal step, one day I may need to. Heck,, Im just gonna, today,, I have a small torch I use for soldering thatll do it,, Anyway, that stuff comes in sizes smaller than a straight pin,or up to approaching 1/4",, 3 foot lengths, great stuff to have in a shop., $10.00 worth would get an assortment that'd surely cover the needs of carb passeges & youd have stuff long enough left over for projects. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by David Bookbinder on 11/27/12 at 11:59:31 True. But the carb kit wires are knurled, may be more effective and less likely to scratch. Found in Amazon for $11 including shipping. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by justin_o_guy2 on 11/27/12 at 19:07:06 One things sure, you would wanna smooth the edges on a wire, Always break those edges. I shoulda mentioned that,, |
|
Title: Re: Next step in trying to eliminate backfiring? Post by LANCER on 11/28/12 at 06:08:14 The few smallest wires are smooth and the rest are knurled but the knurling is not sharp. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by justin_o_guy2 on 11/28/12 at 07:06:11 I think the wire ends on my torch tip cleaner are just lopped off & ragged, & having them attached by a loop to a pin across the end would be about like using an allen wrench built into a kit, Id think, I think Ill just stick with my wire collection, & Berrymans spray & goggles. |
|
Title: Re: Next step in trying to eliminate backfiring? Post by Gyrobob on 11/28/12 at 07:15:33 617E787F62655464546C7E72390B0 wrote:
and ultrasonic cleaning. |
|
SuzukiSavage.com » Powered by YaBB 2.2! YaBB © 2000-2007. All Rights Reserved. |