Backfire On Deceleration Carburetor

The gas did turn bad in the tank during those 8 months so I drained the tank and filled with 93 Octane Shell gas. Yes, it's coming from the exhaust pipe, not the carbs. Too little spark advance will cause low power, bad gas mileage, backfiring, and poor performance. The trick is to let fresh air into the combustion chamber to minimize the backfire effect. What Causes a Backfire Generally, a backfire is caused by an imbalance in the air to fuel ratio. We just put in a freshly-rebuilt 205K distributor and a freshly-rebuilt german 30 Pict-1 carb. It also jerks when I'm just rolling the throttle - such as rolling up to a T junction and gently pulling away without stopping. Stored in the main memory chip (PROM) is the software (values programmed by GM or your custom tuner) that tell the computer, among other things, how much fuel and spark to deliver to the engine for a given set of operating conditions. It wasn't until after these parts were replaced that the backfiring started. I have a 2003 suzuki vinson 500, that started backfiring and stalling out. FIRST, if you have factory exhaust get that AIS back in working order!!! Second, that decel pop may not be a backfire (though im leaning towards is since you say it does it at idle as well) try this, while it is popping on decel squeeze the clutch. It's awesome! But it just started backfiri. a remap should help reduce the popping and probably get u a few more hp. so what do you guys think is most likesly causing the backfire? lack of back pressure,bad gasket,hole in exhaust??? the truck never backfired before i hallowed out the cat. This also occurs when you shut your engine while at high RPM. i herd that my spark plugs. During deceleration, the carburetor will be exposed to extremely high manifold vacuum. Is there an adjustment I can make to eliminate this or do I need new carb parts? I replaced the diaphrams with the carb rebuild. The popping is because the burnt gases can't exit out the exhaust as normal. I checked my valves before I put my engine back in and they are in spec. It's not a loud backfire, just a rumbling and popping. Popping/backfire through exhaust on deceleration Prior to parking it a year ago, the motor had a real bad bog at WOT and one of the intake banks feeding the plugs looked lean compared to the other bank. The low-speed and midrange circuits of the late-model carburetor are not adjusted to give optimum performance - they're set up to produce a minimum hydrocarbon count on deceleration. by Mr Tidy. There are two kinds of backfires related to dirty carbs. At the end of the day, some backfiring on deceleration is going to happen, it's just a matter of how much. If the air cutoff valve(s) is working properly and you still have backfiring on deceleration, something is causing a lean condition. SYMPTOMS OF INCORRECT IGNITION TIMING Symptoms of incorrect ignition timing are poor fuel economy, sluggish acceleration, hard starting, backfiring, or "pinging" or "spark knock". Deceleration Backfire is caused by fuel burning in the exhaust manifold or header. When you hear your motorcycle backfire, there can be a variety of problems with your motorcycle’s engine. The lean misfire will put unburned air/fuel into the exhaust, where it then explodes. The carb bowl will be removed quite a few times during the rejetting process. But the bigger question is how does gas get there in the first place, and that’s a bit more complicated. Hey cody, insanely helpful video. There are many ways to stop the bike from backfiring and some of them are as listed below. Series Land Rover - Engine Backfires. EXO Stainless is the most durable exhaust in our lineup. I made the carb adjustments as per the S&S manual. Incorrect timing can lead to the fuel being ignited before the manifold intake valve closes, causing a backfire through the carburetor or exhaust. Get Yours Today! We know our parts and products. 0L Cherokee automatic transmission that is backfiring on acceleration or load (going up a hill). Any ideas on why its happening? Cheers. FIRST, if you have factory exhaust get that AIS back in working order!!! Second, that decel pop may not be a backfire (though im leaning towards is since you say it does it at idle as well) try this, while it is popping on decel squeeze the clutch. I dont think it was technically backfiring, just popping very loud & annoyingly. Even washing your K&N or Uni air filter and not re-oiling it can cause your quad to backfire. 1968 Pontiac GTO 400 Engine Back Fire Out Tailpipe On Deceleration. thinking this fixed the problem i began to drive her again, only to find she is still backfiring a lot and im noticing a popping/clicking noise around. TM 1-1500-204-23-1 Figure 7-2. The stock carb for that scooter looks like it may have an air cut valve. Since the OP reports being able to feel it as well as hear it I'm also thinking a lean misfire and agree to pull the plugs and see what they're showing. I was looking around this topic for someone who had serviced their "decel" valves on the carburetor without removing the carbs. What Causes a Backfire Generally, a backfire is caused by an imbalance in the air to fuel ratio. Ever since installing the HRC kit, along with a full exhaust system, filter, air box mods etc. Every once in a while when driving I'll get a backfire through the carburetor. What causes backfire on fast deceleration and afterfire when the motor shuts off? Is it running to lean or to rich? Its a Predator 420 and i currently have the stock main jet in that it comes with from Harbor Freight, aftermarket air filter, and pretty free flowing exhaust (14" tractor muffler). Quick question, I have an 82 kz440, and I just rejetted up two sizes as well as adjusting the pilot screw. Yet, tuning a three dimensional map, with consideration for manifold absolute pressure (MAP) is quite labor intensive. In my how-to video I will walk you through the basic principles and fundamentals of what you are adjusting and how it will impact your bike's response. HOW OLD IS THE CARB it could be the ACV diaphgram has holes in it. Whether the engine is petrol or diesel, the common reasons for the engine to backfire in a Series Land Rover are essentially the same. I have this problem myself. First of all let's clarify something: - Backfire is combustion, sneezing, coughing or spitting out of the carb. Unlike the current fuel injected 660s, the old 5 valve carburettor models shouldn't pop or backfire on the overrun. But the bigger question is how does gas get there in the first place, and that’s a bit more complicated. If you are running aftermarket exhaust and K&N air filter then I would also suggest the Dave Dodge main jets (105s are what he sells and work great!!!). Do the same on the other carb. What would cause backfiring of motorcycle upon deceleration? 1956 BMW w mikuni carb occasionally backfires on deceleration, sometimes singularly and sometimes in clusters. You'd better start searching for that now or maybe even a used carburetor, if you can find one. Sluggish Throttle / stumbling when opened up wide. The exhaust has a strange smell, more like fuel than oil. One of the cures is to decrease amount of fuel injected by the accelerator pump when first opening the throttle. While riding bike, exhaust backfires/pops when letting off of the throttle in any gear, very annoying not just to me but to other riders. The bike starts fairly easy and idles well. It has an aftermarket fuel screw in it as well, so I'll double check to make sure everything is in the right order and in good shape. Miscellaneous Carb Questions FAQ compiled & edited by Kristian #562 Please read the Disclaimer before attempting any work in this FAQ. the stock jets were 120 mains, 35 idle. have you checked for leaks? if you have a leak where the exhaust bolts on to the engine it will suck air in on deceleration and cause a popping or backfire. Any misconnected or leaking carb vacuum hoses can also encourage backfiring. It's backfiring on deceleration, at first, didn't notice any flame out the exhaust, but since tuning the air/fuel mixture to a little leaner, noticing a little flame every once in a. This happens if its in gear with clutch in, or if the bikes in neutral so im pressuming its not any more clutch problems. I have removed the pair valve and my current carb setup is a 210 main, stock pilot, needle on 4th clip and 2. (1998 FXSTS) Lately and it's happening more and more, I am getting backfires on acceleration (only after I close (push in) the enrichener), on deceleration and at times just in normal cruising. A lean idle mixture can cause popping on deceleration, but the deceleration popping is usually more mild. The most common method is to simply lean out the carburetor. I don't mind the noise at all, but I'm afraid it'll burn my exhaust valves so I'd like to fix it. 1956 BMW w mikuni carb occasionally backfires on deceleration, sometimes singularly and sometimes in clusters. I find it easiest to use a dime rather than a screwdriver to turn the fast idle screw when the carb is in place on the car. If the air cutoff valve(s) is working properly and you still have backfiring on deceleration, something is causing a lean condition. Most of the time when there is an issue with the TBAP it is due to *broken/bare wires, or occasionally dirt on the TBAP. Without it, the mixture would cool enough not to explode. On a cold day, these temps would be lowered by the ambient temp enough to prevent backfiring. when it spits and backfires is when i pull the choke. i,m working on a gator that is spitting fuel out the carb. EXO Stainless is the most durable exhaust in our lineup. I have this problem myself. Kwell doesn't fall on its face anyway. Turning out the fuel screw an additional 1/4 to 1/2 turn would be an option, but any further starts to compromise the low speed performance with a rich idle to reduce the pop. You may have to register before you can post: click the register link above to proceed. So, I replaced the plugs with autolites and the air filter with a K&N. Its purpose is to prevent popping on decal by pumping a little gas in the carb. if all you have is popping on decel you have one of 3 issues. it's not bad for the engine unless it pops constantly and loudly (like thunderous loud) on decel, then it's an indication of something being out of spec or an exhaust leak. A carburetor backfire describes the small explosion that sometimes occurs when starting up a car. Replaced Spark plug, clean air filter, and fix exhaust leaks still the same. got an 85 k5, stock gm crate 350, carburated heres what ive recently done (within 2 months) redid all plugs, wires, cap, coil and rotor new edlebrock airfilter new in line fuel filter replaced almost all vacuum lines new valve covers and gaskets for em cleaned carb out with some carb cleaner (didnt disassemble though). damn thing sounded like a shotgun goin off. It seems to work fine if I floor the accelerator peddle but hesitates if I accelerate gradually. Thanks again for the pointers guys. It seems to work fine if I floor the accelerator peddle but hesitates if I accelerate gradually. catalytic converter was shot so i hallowed it out. Check all vacuum hoses for cracks and loose connections. 25 inch pipe and a flowmaster and the hallow cat. A backfire is a pop, usually followed closely by a flame out the intake of a given engine. Backfiring on deceleration is caused by a lean fuel mixture. Deceleration popping is not backfiring. If these screws are misadjusted (too far in) it will cause the engine to backfire during deceleration (my experience). Jump to Latest Follow 1 - 20 of 50 Posts Since your backfiring is exhaust, not carb, ignition system shouldn't be an issue. Carburetor/manifold leaks are much less common. If you are looking for performance-related carb information See the Rejetting Spreadsheet accessed via. New Exhaust System = Carb Jetting? When you upgrade your bike with a new exhaust system, air box or hi-flow air filter it may upset the air to fuel ratio creating a mixture that is too rich or too lean. Learn how to diagnose and solve an engine backfiring problem… in case it is a problem. it may make the sound a bit. i used the jetting recomendations on fmfs website and my bike was doing the same thing where is was real popy and would back fire when decelerating. Backfiring is when the fuel/air mixture is ignited and the flame travels back up through the intake manifold and out to atmosphere either through the carburetor or throttle body. Everything over 5,000 was fine. According to Clymer, it may be the air cutoff valve in the carb. **** Remember to check for backfiring on deceleration only after the engine is warm and the. ,running pro kurakyn hypercharger and cobra pro hp 2 into 1 exhaust ,was previosly running with v+h slippons,still the same issue,bike shop having issue resolving this. A carburetor backfire describes the small explosion that sometimes occurs when starting up a car. "My Kawasaki Mower Engine Backfires When. well, yes, it's an air/fuel ratio problem, but there are dozens of different ways that it could be affected. Proper carb adjustment and tight exhaust joints is the best you can do to minimize it. backfiring without having to adjust the idle screw or pilot screw. Torn diaphragms usually present as a bike that won't make full power or does not accelerate properly. Make a little smoke by feeding it a little oil/gas mix or diesel through the carb and. Series Land Rover - Engine Backfires. From replacement fuel bowls to power valves and jets and everything thing in between. On bikes these arent very noticable though, and if you've worked around carbureted cars advance the ignition timing to far and you'll see what i mean about a backfire. It wasn't until after these parts were replaced that the backfiring started. Have any members experience the same and if so is there a known fix. 0 Backfiring/Misfiring under load and part throttle Turns out it was a bad TPS. It does it if i let off the gas around half throttle or more. My zrx 1100 bacfires every deceleration. If I pull the choke about half way out no more popping. (1998 to 2003) The 1998-2003 Non-Sport model used an integrated ICM on the Sensor Plate (which was still located in the 'nosecone' behind the round cover) and was still a Dual-Fire Spark System. Carb Backfire with my 2000 Vulcan 800 Been also getting the backfiring thru the carb on my 2000. Sometimes hard braking can slosh fuel into the carb from the back bowl air vent. sounds good and runs great. And of course, timing off; but I think both carbs would spit if that was the case. In order to go up hill I have to floor the accelerator and kick it down in low gear. A value of positive or negative 15-40 should be added and can reduce popping if it is still noticeable. Note: Backfire and afterfire through the carburetor will not harm the engine at all!. This is not a bang heard out the pipe but more like a ping/pop right in the header. My only guess would be the valves need to be adjusted. Assembled and it still runs great (except the back fire). Let her warm up on full choke (which takes away backfiring) and give her a blip on the throttle. Also talk about Honda's other ATV and UTV's including the Honda Rubicon, Honda Rincon, Honda Rancher and Honda Recon. Carb Troubleshooting & Adjustment Info I started my bike up yesterday and as soon as I hit the starter, a loud pop like a gunshot went off. Have any members experience the same and if so is there a known fix. Item # 19 "diaphragm set" is a deceleration valve that is supposed to help eliminate backfiring by closing off an air passage in the idle circuit. Just got my car back after having a cooling system installed and after taking it for a ride it seems to be backfiring and popping out of the exhaust when letting off the gas. It wasn't until after these parts were replaced that the backfiring started. Exhaust backfire on deceleration Just went for a good drive. How do you rebuild or overhaul a small engine carburetor? August 09, 2018. When you suddenly accelerate, the carb must provide more fuel quickly to compensate for the greater air intake. Mine would do that some, then I upgraded to 1-3/4" LT headers with 3" collectors and 3" dumps while ditching my "H" pipe. Power valve blown. A total of 40 degree is tooooo much advance. If it hasn't been done, back out your needle for the low speed jet about 2. Rich usually just results in an elevated idle until you go so rich that the engine bogs from too much fuel. I have that fixed and rebuilt carb. Excessive backfiring and popping whilst riding. Rapid deceleration can cause a backfire. Even washing your K&N or Uni air filter and not re-oiling it can cause your quad to backfire. SYMPTOMS OF INCORRECT IGNITION TIMING Symptoms of incorrect ignition timing are poor fuel economy, sluggish acceleration, hard starting, backfiring, or "pinging" or "spark knock". Carburetor Parts And Components Holley offers a wide variety of replacement and performance enhancing components for your Carburetor. I am experiencing a backfire on the rear cyclinder. afterfire While we're at it, let's clear up some terminology here. Rich backfire (worse when hot): Lean (screw in) fuel screws 1/2 turn at a time. Say What??? Ethanol may speed the decay of carb diaphragms but one tank DOES NOT destroy them. On the primary carb, there is a special enrichment circuit. TheMotorcycleMD 342,791 views. Replaced Spark plug, clean air filter, and fix exhaust leaks still the same. A carb kit for a 1975 Honda may be harder to find than you think. During deceleration, the carburetor will be exposed to extremely high manifold vacuum. It is usually an adjustment issue and relatively easy to remedy. 0 hours ago and they're right where they're supposed to be with lots of room to wear down. Try turning the fuel screw on the bottom of the carburetor outwards by 1/4 turn steps up to 1 turn. Exhaust backfire occurs when unburned fuel expelled from the cylinders ignites in the exhaust system. I have removed the pair valve and my current carb setup is a 210 main, stock pilot, needle on 4th clip and 2. *New connecter for TBAP #2875542 Kit Harness (Repair Kit ). I have been reading the posts on backfires on deceleration, etc. You have to have the air pump to pass visual an if it's backfiring they are going to know something aint right and look for problems. It is a popping resonating sound generated by a lean condition on deceleration. SET UP ADJUSTMENTS Start set up by confirming carb base line settings. Print Page - 1981 toyota 22R backfiring up the carb. Don't forget to check the intake manifold gaskets! My bike ran great and only on a rare occasion would it pop when backing. Blocking off your intake with stock jetting give you an overly rich condition, big time, and may stop the decel popping at the expense of gas mileage. The car starts and idles fine. This is an indication that too much gas is being burned. Why firing sound occurs on decelerating a bike. It does it if i let off the gas around half throttle or more. Pilot Screw. Backfires on deceleration going down a hill and the pedal is quickly pushed and released. Amazingly an early Ford carb is as simple to rebuild, and adjust as is an air-cooled pre-1971 Volkswagen carb. In general, backfiring on deceleration (as opposed to acceleration) is generally caused by a lean condition in the pilot circuit. The exhaust headpipe can have the slightest air leak and cause a pop on deceleration. FWIW my car pops a good bit, sometimes, on deceleration. Mods: HMF Dual Exhaust, Jet Kit. 29/07/99 Thanks to Emma (emma. The timing is right on the money and carb jetting is stock, same as on the other side. Popping and backfiring CB750. The popping and burbling on part throttle acceleration would point to carburetor problems otherwise. My engine is new and was running fine. EXO Stainless is the most durable exhaust in our lineup. 6 : 1 : 2016-11-20 03:04: Silver Shadow II steering rack question: John Grieve: 9 : 1 : 2016-11-16 06:57: Chapters S9 thru S15 of TSD4200 - has anyone got them? Omar M. It was still plenty in and the bike ran perfect opening the throttle and at steady throttle, but then the misfire & popping on decelerating and occ. Car backfiring is not alarming as long as it involves only screeching sounds. Turn it clockwise until it lightly seats (till it stops) - count how many times you've turned it (so you can put it back to it's initial setting if necessary). I just changed the spark plug. Backfiring on Deceleration. it backfires through the exaust when you increase the Rpms quickly. and back firing. Driveability is as it was previously except that I am now hearing a popping pulse through the left muffler at idle and upon deceleration. Do the same without choke - serious and constant backfire, I can see sparks coming up through rear carb. Make a little smoke by feeding it a little oil/gas mix or diesel through the carb and. The carburetor itself could be producing a lean mix, causing backfire during normal operation as well as during deceleration. It had an annoying afterburn pop in the mufflers. afterfire While we’re at it, let’s clear up some terminology here. But this last few months it has been running rough. I just bought a 1984 Honda 200s. It has something to do with a "deceleration valve" and if that "O" ring is missing the bike will pop and backfire while decelerating with the throttle closed. To get rid of that nasty popping on decel, you have to have more fuel at idle. If it's running right it will pass even with gutted cats. But on that note, again, my understanding is the carb was rejetted when the FMF exhaust was put on. If the O ring is missing, it will pop. Backfiring when letting off the throttle indicates running rich,(unburned fuel igniting in the muffler, for example plugged filter), Backfiring while under load indicates running lean,(not enough fuel, for example adding a pipe or modded airbox but not rejetting). Back fires only after you gas it good and then let off. This extract from the Virago Site explains it succinctly. Reading plugs now is basically impossible with all the additives added to the fuel. If this is the case, would using higher octane gas help? (I'm thinking lean = detonation, which higher octane gas prevents). The mixture usually burns hotter than a normal mixture so a lean air/fuel ratio will not only cause the backfiring you are hearing but it may damage the exhaust valve and exhaust valve seat. It is especially vulnerable to engine backfires. Real backfiring is actually the bike "spitting up" in a sense, backwards through the carburetor or intake. 5 idle and threw one shim on the needle. Tips to Prevent Backfire. It does have a FMF powder bomb complete pipe system. I'm sorry if this an old topic, but i'm a new owner with absolutely no expertise. at the fuel block at carbs. An air-cut valve is used to prevent popping in the exhaust system during deceleration. Fixed them. We just put in a freshly-rebuilt 205K distributor and a freshly-rebuilt german 30 Pict-1 carb. 83 22R backfire, read the shop manual and checked everything. (we never have perfect and complete combustion, if we did the EPA would love it) These leans gases are above the flash point of the gasoline. Low fuel pressure, clogged filters and weak pumps are some other causes of backfire. At the end of the day, some backfiring on deceleration is going to happen, it's just a matter of how much. Replaced Spark plug, clean air filter, and fix exhaust leaks still the same. Check for cracked or stiff bending hoses and replace if necessary. com has the best deals and lowest prices on vulcan backfire irons set steel. Backfires on deceleration is simply the process of burning the excess fuel left the combustion chamber. Again, a cackle on sharp deceleration may be perfectly normal. just gonna have to do a little more fine tuning. i cant get a hold of the guy who owned it before me so i cant ask him about the bike but he did say it had a big bore kit. 2-barrel Carb. Back if off to that level you should still have great out of the hole performance. 1600 S single Solex 34 PICT3 carb The timing (0 - TDC at idle and advance at 2200 RPM is 18deg) idle speed is 750 RPM dwell angle (50 deg), points gap at. It is a 598 BB with a holley 1000 carb. On some 22R, they are equipped with a decel valve mounted on top of the right fender, which redirects the air injection between the exhaust ports to the air cleaner and what not, it is there to lower the emission out the tail pipe. afterfire While we’re at it, let’s clear up some terminology here. The next thing to check is the timing chain. It seems to work fine if I floor the accelerator peddle but hesitates if I accelerate gradually. It is usually an adjustment issue and relatively easy to remedy. The mower's engine attempts to bring engine timing in line with the lower throttle. I just pulled the wires out of the plugs and cut about 1/4" off just to make sure. Cruising Mixture Check valve for nozzle not holding, Check - continued pumps not synchronized, vapor vents stuck, low cylinder head temperature, or improper spark plug gap. The most commonly asked questions about carburetors and carb tuning are answered right here. According to Clymer, it may be the air cutoff valve in the carb. One of the cures is to decrease amount of fuel injected by the accelerator pump when first opening the throttle. it's not bad for the engine unless it pops constantly and loudly (like thunderous loud) on decel, then it's an indication of something being out of spec or an exhaust leak. With the ignition key in the OFF position and the seat completely removed, press the accelerator pedal down. It does it if i let off the gas around half throttle or more. The bike has never run better with still less than 10K on the clock. & it fired up the first time but it had a little bit of back fire through the exaust and carb. But it sounds like a vacuum leak. well, I checked the timing at idle with the vacuum advanced disconnected and plugged. We usually refer to an exhaust backfire as a "backfire", and backfiring through the carb as "spitting" or "coughing". It gets worse if try to hold at that speed. the stock jets were 120 mains, 35 idle. Hey everyone, In the diagram below part #40 is broken on my 400ex. have you checked for leaks? if you have a leak where the exhaust bolts on to the engine it will suck air in on deceleration and cause a popping or backfire. Did not hear the bike rev any louder. Mods: HMF Dual Exhaust, Jet Kit. This is also more than a popping out the exhaust - it is more like a handgun being shot. It starts first pull on half choke every time and idles okay until it warms up. Note: Backfire and afterfire through the carburetor will not harm the engine at all!. The engine still has the backfiring problem on deceleration but is now choppy in acceleration with a little pinging noises inside the engine while accelerating. Other possible symptom - getting some exhaust popping on decel. *My carb took 1 3/4 turns on both mixture screws to run right. 40 New plug cords, new spark plugs, condenser and points. If your vehicle has a carburetor then the choke plate may be stuck. Motorcycle Backfire on Deceleration - How to Replace a Carburetor Diaphragm Deceleration Backfire: Tuning your carburetor - Duration: 29:22. Why does my car backfire on deceleration? Maybe backfire is an exaggeration, but when I let off the gas the car will burble and pop through the exhaust while I decelerate. 83 22R backfire, read the shop manual and checked everything. This normal tendency is controlled by the air cut-off valve(s) operation. My dad's Rhino would backfire when you let off the gas. If it is backfiring out of the carburetor, the pilot is too small. Through reading different forums I found out that the remedy to this is taking off the smog(SAS valve and the EVAP system) To do this you will need to take the tank off so that you can get at everything. A carburetor backfire describes the small explosion that sometimes occurs when starting up a car. WHAT CAUSES BACKFIRING IN 72 BUG? - I have just had my EARLY 72 bug brought back to life. Other possible symptom - getting some exhaust popping on decel. The backfire is caused by too lean a setting of the pilot circuit. So I shut it down for about an hour, than went back out. I need to get a carb kit and just haven't gotten around to it. caterpillar cross reference. Idles poorly - Fluctuations in idle RPM, stalling. If you have an exhaust valve that is not openning, this will cause popping back through the carb especially when under a load or at higher RMPs. A back-fire or backfire is combustion or an explosion produced by a running internal combustion engine that occurs in the air intake system rather than inside the combustion chamber. have you checked for leaks? if you have a leak where the exhaust bolts on to the engine it will suck air in on deceleration and cause a popping or backfire. Also, when I was decelerating and I didn't pull in the clutch, I was getting some mad backfire out of the new exhaust. The low-speed and midrange circuits of the late-model carburetor are not adjusted to give optimum performance - they're set up to produce a minimum hydrocarbon count on deceleration. The bike has always popped on deceleration. More puzzlingly, seemed to talk about the carburetor, which I wouldn't think would even be in the equation on deceleration. Engine Conditioning - CONT Complete conditioning When Personnel steps Procedure performed responsible Step 12. hasn't run since 2005. I checked my valves before I put my engine back in and they are in spec. 2-barrel Carb. The 1986-1997 Ignition Control Module was located under the Triangle Cover on the left side of the bike next to the battery. Did not hear the bike rev any louder. If the O ring is missing, it will pop. On the road, the popping on deceleration COMPLETELY disappeared and idle is noticeably smoother so that was it folks. He disagree with me with everything else!! It was a heated argument. hello all, learning more and more about this bike as time goes on. its not backfiring through the carb though. It turned out to be a plugged fuel filter. Quick question, I have an 82 kz440, and I just rejetted up two sizes as well as adjusting the pilot screw. There are can be other causes but more information is needed to help point you in the right direction. How to Make a Car Backfire. I noticed when I let off the throttle the AFR leans out to about 34-35ish after a second or two and that's when the exhaust would have a loud backfire/pop. When the bike is idling and it backfires, it will die most of the time. TW -----This is exactly correct! If you think about the mechanics of what is going on upon decel, it makes perfect sense: You start out with an engine that is turning high RPM with a carb that is open, flowing freely. chevy 350, timing. I have done over 25 of these on the '94-'03 Magna's and it cures the midrange issues as well as the deceleration popping. What causes backfire on fast deceleration and afterfire when the motor shuts off? Is it running to lean or to rich? Its a Predator 420 and i currently have the stock main jet in that it comes with from Harbor Freight, aftermarket air filter, and pretty free flowing exhaust (14" tractor muffler). Cleaning the idle circuit passages requires compressed air. [B]When a car backfires it usually has to do with the timing. I can only assume this was a backfire. Print Page - 1981 toyota 22R backfiring up the carb. Could have been crap in the carb or crap on the exhaust valve seat, I don't know but it's fine now. I have an 85 virago 1000 with 20000 miles. Most of the time when there is an issue with the TBAP it is due to *broken/bare wires, or occasionally dirt on the TBAP. The problem I am having is once it warms up it won't idle. This cause particularly makes that popping sound on deceleration. I'd pull the bowls make sure it's all clean inside. If the air cutoff valve(s) is working properly and you still have backfiring on deceleration, something is causing a lean condition. if it backfires on deceleration its lean if it pops on acceleration its running rich. any common jetting size pms etc for this issue would be appreciated. I just pulled the wires out of the plugs and cut about 1/4" off just to make sure. Is this indicitive of running lean? im running a tb 20mm with a 90 main and uni street filter on a 110 lifan with an R&L exhaust. On a street bike, the rule of thumb is to adjust the fuel mixture screw out in ½ turn increments to add fuel.