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/cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> Loud afterfire on decel from 50 to 30; tuning Q's /cgi-bin/YaBB.pl?num=1560118898 Message started by Majorfatboy on 06/09/19 at 15:21:38 |
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Title: Loud afterfire on decel from 50 to 30; tuning Q's Post by Majorfatboy on 06/09/19 at 15:21:38 Finally got My bike running... Mostly. Story to date: First: Bike ran for crap since the day I got it, late April it developed an issue where it would after(or back, don't know for sure)fire FREAKING LOUD and die. Eventually left Me stranded on the side of the road awaiting a tow. Couldn't get to repairs quickly due to it raining nearly every day and other life-related fun. What I did to it, round 1:
Result round 1: Bike ran like a raped ape, MY GOD THE POWER. No more dead spot in throttle just after You open it, smooth as silk, 0-to-25 range is actually ridable, not a bucking shuddering joke. Engine has wider range between gears, not as narrow and picky. But it was rich as hell. Stank of burnt fuel, even though I only had the mixture screw out half a turn, any more than that rpm didn't seem to rise much audibly, but it reeked of gas. Could just about close the screw to 1/4 turn out before the engine started to choke. Not a single pop or afterfire except for one moderately loud pop decelerating gently (rolling off the throttle slowly) from 60 to 50. Didn't want to run it rich to the point of stinking, as much as I loved the RAW FREAKING POWER, so I decided to rejet...
Result round 2: Bike is slightly tamer power wise, but still runs better than it used to. But now it pops loud when decelerating from 50 to 40, or from 40 to 30. It never used to do that in either it's crappy original state, or in the above 52.5 jetting. Mixture screw simply isn't giving the symphony of tones You guys state it should; Engine chokes at about 1/4 out, fastest audible idle is at only about 1 full turn out, maybe a bit more. I've been out on a few test rides, and have tried the screw at 1, 1.5, and currently 2 full turns out, still get LOUD pop during decel in the 50-to-30 range. To rule out vacuum leak, I'll re-snug bolts on the carb and hoses, was thinking of doing the old wd40 trick for a leak test. I just want this pile of crap to run. The amount of trouble it seems to cause Me, along with how poorly designed it is, has convinced Me to get it in running shape (somehow), use it for the rest of the season, and sell the turd next year for something that wasn't engineered by screwheads. But until that glorious day, You lot have any tips for getting it to run without doing shotgun impressions whenever I roll off the throttle in traffic? Being forced to clutch in and ride the brakes for a simple 5/10 mph speed adjustment and miss out on engine braking is silly. |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by philthymike on 06/09/19 at 15:59:23 Try tightening the header to the head. When it works loose lots of machine gunnery ensues. Maybe replace the crush washer for the header. Doing this has nearly eliminated all backfiring on my bike. |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by batman on 06/09/19 at 17:50:08 My guess is your elevation is above 1000 ft.( should tell us when talking about your carb) ,you need to reinstall the 52.5 stock pilot jet ,and install a third washer on the needle jet . You went to a 50 pilot to lean your mix ,but that only leans it at idle( OR anytime you decal), but you only put two washers on the needle jet which made it rich and you've had to set the idle speed screw(under the choke nob) in to bring the idle up to normal ,bringing to much fuel in by way of the main jet/needle ,and that's why you have little reaction when tuning the idle mix screw. |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by Majorfatboy on 06/09/19 at 18:56:08 7477627B7778222E160 wrote:
604 feet elevation, which as I understand it is usually low enough to be considered "sea level", or low altitude, so I hadn't considered that as an issue. I live in SE Wisconsin, where God sends ALL of the crap weather. So go up to three washers on the needle, which would lean the mix at the higher speeds/throttle wide open conditions, and go back to the 52.5 pilot, enriching the mix on idle/low speeds/throttle barely open conditions. Worth a try at this point, thanks. Will also poke around the header as Philthy suggested. |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by batman on 06/09/19 at 21:11:08 I'm in central N.Y. I live at about 1300 ft . but often travel to 450 ft . My setup is 52.5 /150 jets and 3 washers on the needle , I'm probably run a bit rich at home ,a bit lean when I'm ,say on the N.Y. thruway between Albany and Buffalo , I suffer no hard backfires and rarely a soft poof at shutdown . You could try just changing back to the 52.5 pilot first, and tuning the mix screw ,that alone should kill the backfiring , if your still running rich after that ,then add the extra washer. It's always a good idea to make only one change at a time ,that way if things go south , you can just reverse your last change, and try something different.Each bike is a little different you may have to go to a 55 pilot but I don't think so. Be sure to ride the bike until it's fully warmed up ,and slow the idle(almost to a stall) so that you can hear the motor change speed when tuning the mix screw. then reset your idle to normal good luck! |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by ohiomoto on 06/10/19 at 06:39:19 I'm at 600-1100 feet and run 47.5/147.5 jetting, stock airbox and dyna muffler. Pulls clean and smooth, almost no deceleration backfire and a slight poof on shutdown. Make sure there are no air leaks and that your idle is set properly. These things don't like to idle low like a HD. Should be around 1100 rpm I believe. |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by Gary_in_NJ on 06/10/19 at 07:02:29 A few things. The mixture screw only effects the idle circuit. By1/8 throttle you are off the idle circuit and on the needle. You’ll be riding the needle until about 3/4 throttle. If the bike is running rich it’s usually a problem of the needle, because that’s where you spend 90% of your riding. The afterfire is probably not a result of the jetting, so go back to the setup that gave you the best power and throttle response. These bikes with the OEM carbs afterfire. Get use to it and learn to smile when it happens. Excessive afterfire may be a lose exhaust or cracked flange/gasket at the head. |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by batman on 06/10/19 at 07:45:29 Ohiomoto , your bike running a 45 pilot? 7 sizes down from the stock 52.5 . Dream on. even an 86-87 runs a 47.5/155 jets, stock. With that size jet your motor should be glowing in the dark, sitting at red lights, either that or your idle speed screw is all the way in and your running on the needle jet, even at idle if it's is truly 1100 rpm. Please don't tell me you haven't done the spacer mod as well. |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by ohiomoto on 06/10/19 at 08:51:39 77746178747B212D150 wrote:
Typo. 47.5 pilot which is only TWO sizes down from stock (a 45 would be 3, not 7 BTW). I'm using a 3/4 spacer. Half was too rich. Since I spent a lot of time tuning motocross bikes growing up, I actually know how to test jetting. Everyone claims how lean this bike is from stock and it's just not working out that way for me. As "lean" as I am now, my bike still runs better in cooler temperatures that it does in the dog days of summer.* It starts up and is immediately ridable on half-choke in sub-40 degree weather. I only begins to surge at steady throttle when it gets below 35 degrees. The bike runs and sounds completely different than it did when I got it. The PO had a 55/155 combo in it. It sounded cool, but it had a slow steady pull, no throttle response, topped out at a little over 70 mph, there was carbon all over the rear wheel, the plug was almost wet and it only got about 32 mpg. I get 50 mpg now, I get solid throttle response from anywhere and the bike will pull a quick 80mph before it begins to fall flat. I can short shift it anywhere in the power band without falling on its face. It's about all I think I could expect for what it is. I'm a firm believer of using information to help make informed decisions, but ultimately you need to test the results for yourself. My testing showed me what works best for my bike. To each his own, but I wonder if people are overlooking some simple tuning clues. Until your reach extremes, a slightly rich condition and a slightly lean condition will produce a soft spot in the power band. Both can produce backfires. You can muck around with jetting all day long, but the absolute easiest way to determine with direction to go is to ride the bike during the coolest part of the day and compare it to the hottest part of the day. I leave for work every day at 6 am and ride home at 4 pm pretty much every dry day that starts out above 35-40 degrees. Dream on??? Okay. *I'm really not even jetted lean. One pilot jet leaner than the very common 50. One main richer than stock which is only one main leaner than the commonly used 150. White spacer 3/4 is richer than stock. |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by Dave on 06/10/19 at 11:23:24 Ohiomoto: I agree with you.....it is very easy to throw in jets and get the engine "too rich" - and then accept that as running good. Being on the rich side allows the bike to start easy, run pretty smooth and act normal - and it might seem that all is well. However - once a bike is tuned properly it is amazing how "crisp" things become and how much better they engine runs. Some of the folks complain about the CV carb not being quick to respond....and I sometimes wonder if any of that comes from the jetting being too rich? My savage with the stock carb used a #50 pilot, #150 main and 2 washers...it still had a lean surge if I used 3 washers......on a few other bikes I was able to use a #52.5 pilot and 3 washers. I ride' at 500-800' elevation normally - on trips to the mountains I can sometimes get up to 4,000' and it still ran well (but if I lived in those areas leaner jetting might be required). I really believe folks need to experiment with the jetting - they should not just throw in a #150 main because I did. I believe a #150/#50 and 3 washers gets you in the ballpark.......then it is time to take some changes and see what happens - trying other size jets to see if they can make things better for their bike. Dave |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by VortecCPI on 06/10/19 at 12:49:37 We use the Mikuni Roll-Off Method to check main size: http://www.mikuni.com/tg_main_jet_size.html The Roll-Off technique is the quickest and is almost as accurate as the Roll-On method. First, one gets the engine warm on the way to a safe roadway. If there is room, use fourth gear as this allows more time to assess the result. Now, get the engine rpm high enough that it is on the cam and in its power band. This may need to be as high as 4000 rpm with some cam choices. Apply full throttle. Let the engine accelerate for a couple of seconds until it has settled in and is pulling hard. Quickly roll the throttle off to about the 7/8ths position. When you do this, the mixture richens slightly for a second or so. If the engine gains power as you roll the throttle off, then the main jet is too small and you need to fit a larger one. If the engine staggers slightly or has a hard hesitation, then the main jet is too large and you need to fit a smaller one. |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by VortecCPI on 06/10/19 at 12:56:11 THE MOST important thing to do before ANY jetting is to check/set proper float level. My wife's 2012 was too lean on the slow/pilot because to get best/fastest idle I was close to three tuns out on the idle mixture screw. Now it is at about 1.0-1.5 turns out in the summer and 1.5-2.0 turns out when it is colder. Main jet is good but I do not remember if it was a 150 or 152.5 but there is not much difference between the two. An air-cooled engine subjected to ever-changing ambient air temperature coupled with ever-changing head temperature means jetting will NEVER be 100% correct. The best we can hope for is very close... Or use a Dial-A-Jet... |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by batman on 06/10/19 at 13:35:00 Like I said each bike is different, Ohiomoto's pulls cleanly to 80 mine pulls hard to 90, Dave yours runs good ,but you are small and 150 lbs.and your bike is about 80 lbs lighter and your running higher compression and high octane gas . My bike may be heaver than stock running full Harley fenders and I'm riding two up most of the time ,I know I'm running a bit rich but it's a 95 without the anti-kickback gear so I run rich to protect the starter gears and side case from damage (I can't afford a heavy backfire at shut off) I run 52.5 /150 -3 washers but still gets 51.5 mpg on E87 and my plug looks good. My motor is stock but for a Dyna muffler , All three bike run well but all require a different state of tune. but we are all running at nearly the same elevation . Majorfatboy"s problem was that he was running rich at speed (which could be from having only two washers on the needle ,but could also be caused by the wrong air mix screw he used to from a rebuild kit) so I suggest he add a washer, his other problem was when he closed the throttle the bike went lean and backfired ,with a 50 pilot ( this lean condition could be caused by the wrong air mix screw ,but I thought that unlikely given that it was nearly closed off), so suggested he return to the stock pilot jet. In hind sight I should have suggested he should start by installing the proper air screw, and be sure the TEV valve and passages are clear before a rejet. |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by Majorfatboy on 06/10/19 at 19:24:43 Update: Pilot jet back to 52.5, three washers are now on the needle, mix screw at 1.5 out. Went out for a roughly 12 mile ride. During the first couple of miles, there was still some pretty bad afterfires during 40-to-30 decel, didn't get a lot of chances to get up to speed, as the roads nearby are so bad, people not only follow the speed limits, but go under them. After a while though, as the bike warmed up I assume, the loud after fires seemed to go away. May just be coincidence. When I got home, I tried tuning again; Brought idle down to a Harley-esc slow pace, and went to the mixture screw. Still not getting any changes in engine tone or speed. Engine start's to bog out at about 1/4 turn out, seems to peak at about 1/2 turn out. Anything beyond that just seems to stink more or less depending on how far out I turn the screw. Will check header pipe and carb mounts for leaks tomorrow. 7370657C707F2529110 wrote:
Not an option. As I said, the original one's lost, wind blew it, as well as My original air pilot screw and main jet, away a few weeks ago while I was working on the bike. But also again, there's nothing to suggest that My replacement is not "proper", as the only difference I know of is that the head is longer, which would have no affect in the needle-end that goes into the carb. If anyone has a nice hi-rez image of a stock mixture screw, perhaps beside a ruler, I could pull My replacement and compare. 7370657C707F2529110 wrote:
Already done. The carb was stripped, blasted with carb cleaner, blown out with compressed air, and everything was reassembled. The TEV's just about the only thing that's easy to get to on this bike though, so no harm in opening it and re-seating the spring and diaphragm I guess. I put spiffy new hex bolts on it and everything. I checked the float height when I had the carb off the bike with a digital caliper, can't remember the measurement off hand, but it was within the Clymer's manual's specs. Honestly, as long as it's not blowing it out it's ass like a cannon, I can put up with it, not looking for pure silence. |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by batman on 06/10/19 at 21:26:20 You could also chase the rather small passage behind the "finger"of the TEV valve with a fine piece of copper wire ,and spray again. I would at this point, order a new stock air screw ,spring washer and O-ring. I wouldn't trust the one from the rebuild kit, cost of all 4 being about $15.00 Screw ,Pilot air -13269-37400 Spring-13268-47070 washer-13291-29900 O-ring -13295-29900 |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by Dave on 06/11/19 at 03:32:41 The proper sized pilot jet should provide the "best" idle with the fuel screw turned out around 2 - 2.5 turns. If you need more than that the pilot jet is too small......fewer turns means the pilot jet is too big (especially if the engine still runs smoothly with the screw turned all the way in). You should be jetting your carb for what the engine does when it is running - not for what it does when you close the throttle. When you close the throttle completely, it closes the butterfly and creates a very high vacuum situation - a lot of air can be pulled past the butterfly by the high vacuum and the only fuel that flows comes out of the idle fuel circuit (and some from the TEV). This creates a lean condition and the fuel/air mixture is so weak the spark plug cannot ignite it......but it can be ignited in the exhaust system - this is what creates the popping explosions in the exhaust. The TEV valve is supposed to add fuel when the throttle is closed and reduce the noise - but even a proper working TEV valve provides marginal help......I believe it was sized when we all used gasoline with no ethanol in it, and it is not providing enough fuel to stop the banging/popping. Some folks fool with the spring - but I don't think the problem is "when" it comes on - I believe the problem is that it just doesn't provide enough fuel and some way needs to be found to change the jets to provide more fuel from the TEV. (When I can find some time I will study a carb and see if I can see what contrils the fuel/air mix added by the TEV). What muffler do you have on the bike? The more open the muffler the worse the noise is going to be. And....this problem is not unique to the Savage - every day you can hear the V-Twin Harleys with loud mufflers popping and backfiring when they let off the throttle (but they seem to love the noise). My advice is to jet the bike for how it runs when you are "on" the throttle or are riding at a steady speed - and learn to use throttle control to lessen the noise. When you shift gears you can slowly roll off the throttle as you shift - but don't let the throttle slam completely closed....leave it open a slight amount. Same thing for your deceleration from 50 - 30 mph.......don't close the throttle completely and just roll on enough throttle to stop the noise. You don't need to add so much throttle that the bike is accelerating - just 1/8th open so the engine gets some fuel and the lean condition in the carb goes away and the bike runs smoothly. The Savage is a primitive bike with a primitive fuel system.....it is not fuel injected.....and you can learn to work with the bike and become a "rider"! After you do this for a little while it will become second nature and you won't have to think about it.....most engines really don't like you to "crack or slam" the throttle open or closed instantly, and respond better to having the throttle rolled on or off. My Cafe' bike has a round slide Mikuni and it does not have a TEV valve, and if I close the throttle completely while decelerating I can pop and bang with the best Harley.......or I can use a slight bit of throttle and the bike runs nice and smooth while slowing down- it is all in the wrist! |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by VortecCPI on 06/11/19 at 04:04:11 68535E4958544F49525A57483B0 wrote:
When my wife's bike was stock best/fastest idle was attained with the screw 2.5-3.0 turns out so I went up one size. This also helped part-throttle leanness just a little bit. A lot of dirt bike guys run a slightly-rich slow/pilot to aid engine cooling. As mentioned earlier every carb is different so each must be treated on its own. However each should run pretty good with a starting baseline. In the dirt bike forums when the baseline jetting does not work the issue is always fuel/float level. The only time my wife's bike backfires is if you slam the throttle closed with a lot of engine speed. If you roll it back slowly (i.e., not all the way closed) it does not backfire. My 1986 Yamaha SRX600 single with SuperTrapp system never backfires, nor did my Twin-Cam HD with V&H Pro Pipe or the two Honda XL/XR 600s I have spent a lot of time on top of. |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by ohiomoto on 06/11/19 at 05:36:56 My point to all of this is that a) we shouldn't be handing out jet sizes like prescriptions (suggestions are good but users need to test) and b) everyone always suggests jetting on the richer side, but that MIGHT not always be the case. BTW, I'm 6'3" 250 lbs and I honestly don't want to go much over 70 mph on this bike so I'm happy to shut down at 80 mph. I think it will probably go another 5 mph, maybe 10 going downhill. :) |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by batman on 06/11/19 at 06:47:32 It seemed obvious to me that his bike was lean in the pilot circuit and running rich in mid range , and that a smaller pilot and only 2 washers on the needle seemed just the reverse of what was needed to make the bike run a bit better, but I think at this point being sure the air mix screw is in fact stock, would be the better starting point. Yes my bike does 90, but I use that as a tuning guide ,I don't ride at that speed ,I'm a 5mph over the limit rider , 80% of the time riding 2 up (245lbs) I am much more concerned with safety, than with speed , being retired I enjoy miles of smiles, and have all day to get there. |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by Majorfatboy on 06/11/19 at 17:19:21 @Batman: Thanks for the OEM numbers, looking at part pictures now, will pull My current mix screw later and compare to make sure, but there may be some slight differences between the two at the needle point. Still not entirely convinced it's the problem, as My problem is while I'm at speed, not at idle, but it couldn't hurt to try. Cost's insane though, most places so far want about nine bucks for the screw, and several bucks S&H. And I'm quite magnificently broke at the moment, lol. Didn't have time to get to the bike today, and They're talking rain again tomorrow, but the TEV's on the list for re-exam, along with the header and carb mounts. @Ohiomoto Brother, I agree 100%, but here's the thing: Anyone who so much as mention's this bike's name on the internet gets shoved over here. "Oh, an S40/savage? They have a website for that, You should ask Your questions there. Now scram". So here We all are, and everyone here will push two things: A new petcock (rightfully so, the stock one's crap), and re-jetting and modding the carb. So a newjack's going to do what the "experts" tell them. Any dialog here slams to a halt until You do these two things with this crowd. "Hey guys I'm having X problem." "Did You do the slide mod and rejet?" "Well, no..." "Well obviously that's Your problem!" Yee haw. I've been lurking Thumpertalk, as they seem to have great heaping gobs of info on things You can do with this style of carb, but there's no point in Me posting there, as They'll just send Me here. The S40's not an off-roader either, so yeah. @Dave: I'm not chopping the throttle, not even close. The decel kabooms I'm getting are from Me already doing what You are recommending; Slow, steady roll off of the throttle. Example 1: I'm cruising at just over 40 with traffic. Traffic starts to slow down gradually. Equally gradually I roll off the throttle, matching speed. KABOOM. Example 2: I'm cruising at just over 50 on an empty stretch (no one behind or directly ahead of Me). I see a traffic light far ahead turn yellow. Time to decelerate. There's no rush though, given My current speed and range to said traffic light. I ever so slowly roll off the throttle. KABOOM. That's why I'm working on this. This isn't from hard/sloppy riding, as I said the bike didn't do this in it's stock config before it broke down. Originally it just ran like crap and did a bunch of small rapid-fire pops when engine braking in second. I am, as You put it, "jetting your carb for what the engine does when it is running - not for what it does when you close the throttle". most engines really don't like you to "crack or slam" the throttle open or closed instantly, and respond better to having the throttle rolled on or off. You're not actually reading what I've been posting, are You? At no point have I stated anything to this nature. I know how to operate a bike, I don't beat the thing like it owes Me money. Especially on this bike, it's to temperamental to treat harshly. Now those Harley Street 500's I was on at the MSF course a few years ago, those bikes could take some abuse. Newer tech though. and you can learn to work with the bike and become a "rider"! Really dude? And what do You think I am now? The muffler's stock, by the way. Everything is, accept for the Raptor petcock and carb mods, both of which are religiously pushed by this very website. Will probably tinker with it over the weekend, considering putting it back to stock (white spacer, 145 main) just to see what happens. |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by ohiomoto on 06/11/19 at 20:25:58 First, I think Dave might have been backing me up as much or more than he was instructing you. Second, I think you have this under control. You are pretty much going in the right direction, but let me point out a few things that might make sense. You seemed to have solved the issue that left you stranded (let's assume the petcock or cleaning the carb solved the issue). But you did a lot of tuning while you were in there based on what is commonly recommended by many on this site. (I'll add that most of the people giving you said advise are really smart and know their crap. I'm sure their bikes run well.) While I think it's reasonable for someone to want to kill two birds with one stone, I'm not a fan of changing anything until after you solve the issue that was leaving you stranded. The reason I don't like it is because the issue that left you stranded could have been the issue that was causing your bike to run like crap before it left you stranded. But you don't now for sure because you changed a bunch of other stuff. Now you're chasing your tail. I'm not picking on you, it happens all the time around here and I've been there and done that too. I would have recommended testing after the petcock replacement before taking the carb apart at all. If it still ran terrible, I would have taken the carb apart to see what's inside. If I found stock jetting, I would have checked the float level, cleaned it up and put the stock jets back in. A completely stock bike should run decently well if there are no issues. If it's running terrible, then you still have bigger issues than jetting. Moving on to where you stand now... I might be the only one on here who actually thinks that it's is possible that our bikes are actually too rich off the bottom end from the factory. If you read through my posts, you'll see that my bike runs great at very low temperatures with almost no warm up. Lean running bikes don't do that. Oh, it doesn't backfire either...interesting. (It will crackle and pop if I rev the piss out of it and chop the throttle closed.) See where I'm going here? I have a 47.5 pilot, a 3/4 spacer and 147 main. (I'm thinking I could run a stock white spacer with a 150 main, but I'm too lazy to bother since I'm satisfied with how the bike runs now.) My gut tells me that the stock jetting is actually a tad rich off the bottom, pretty close in the middle and a little lean on top. I think that the slow bottom end throttle response and backfires on deceleration could be attributed to a rich condition just off idle. If you clean up the bottom end, you may be able to fatten up the main to get that smoother, longer pulling power you like. Then you can adjust the needle as needed and even revisit the pilot again if needed. Lastly, I think that the condition of the slide can not be overlooked. If it's sticking it will cause all kinds of dead spots in your power delivery. I was chasing a dead spot in the middle with my bike until I replaced my slide. The black coating was worn pretty good. I tried cleaning it, but when I realized that I had that dead spot no matter what jets I had it was time to get a new one. $125 later, my dead spot was gone. Best money I spent on that bike to date. I'm not claiming I know anything more than the rest of the guys and gals on here. I'm simply sharing my ideas and experience. You need to find out what works best for you. And please share your findings with us so we can all learn from them. |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by VortecCPI on 06/12/19 at 03:37:43 7B7C7D7B797B607B140 wrote:
What is your elevation in Ohio? |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by Dave on 06/12/19 at 03:40:50 What does the TEV diaphragm look like - is it soft and pliable.....or stiff? When they get aged and stiff, the TEV valve won't open when it should and could contribute to the popping and banging. They don't last forever, and I had to replace the one in the 2002 that I worked on. You can find aftermarket replacements on eBay pretty cheaply....it is a diaphragm used on other carbs as well. |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by VortecCPI on 06/12/19 at 03:53:06 122B3630212707140D440 wrote:
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by batman on 06/12/19 at 16:30:08 Majorfatboy , sorry about your budget ,but the truth is you can't afford to not buy a new stock air screw. just as your valves in your head need to be ground to MATCH the seats in the head so must the air mix screw match the seat in the carb body. even the float level valve in the bowl is sold only as an assembly -matching valve and seat . It's that important, if you can't regulate the fuel/air mix in the pilot system ,your chance of stopping the backfires is very poor. |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by ohiomoto on 06/13/19 at 06:11:41 Batman is correct, the proper screw should be used. That said, the screw does so little in the grand scheme of things that it shouldn't prevent you from getting the bike running reasonably well. @ Vortec...600-1100 feet in my area. |
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Title: Re: Loud afterfire on decel from 50 to 30; tuning Post by VortecCPI on 06/15/19 at 04:46:54 6562636567657E650A0 wrote:
About the same here in CLT. Interesting that you are not lean on the needle and I am. I have checked for proper fuel/float level so the only thing left is needle height. Other than slight part-throttle leanness the engine runs VERY strong from idle to top. The extra slide hole also helped a lot. |
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