Backfire Through Carb Motorcycle

Trying to maneuver it around the garage and in my inclined driveway is a herculean feat. I think it was carburetor related. Just bought the bike and everything on the bike is still stock other than minor accessories. Some atmospheric effects can make small changes that are up or down with increasing altitude, but the over-all trend is down with increase in altitude. Sometimes will backfire (yes a real backfire through the air intake) sometimes "backfire" (impropper fuel burn) through exhaust pipe; Here's what I've done and know: Battery is new and charged The fuel is fresh, clean, and has a new inline filter to carb. While looking around I noticed that the gap on the ignition coil was. 5 Reasons Why Your Car Backfires. Fuel is flowing, the backfire through the carbs is because there is unburnt fuel there. 1 - The original backfire issue came out of nowhere. It started back fireing through the carbs. Take a sewing needle or something of that sort and bring the idle screw down until the needle will barely slide underneath one butterfly (try and remember how many times you turn it so you can get it back to where it was when you're done). Look in the lower right-hand portion of the image, this is the area of the accelerator. Unburnt fuel that is ignited in the exhaust system can produce loud sounds even if flames are not present at the tailpipe. We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon. Fresh air is drawn in through those tiny holes and provides sufficient oxygen to ignite the unburnt gases inside. , strong spark, mixture. When an exhaust pipe is changed, this causes an unbalanced air-to-fuel ratio. All three of these issues have a direct effect on the air-to-fuel ratio. Use 64panhead's sequence, EXCEPT be sure to turn the choke OFF before kicking it with the ignition ON. By: Bill Tichenor 12/02/2009 < Back to Blog Home. I had the carb rebuilt a couple of years ago with a new sleeve and dissimilar slide by a guy I trust. Any help on this would be greatly appreciated. the left carb - will get rid of the backfire 2. I have this problem myself. Hesitation under heavy throttle: Deadspot & stumble. Went out and finally managed to get my exhaust fitted to my downpipes using a gasket I made from a can of Macaroni Cheese Anyway, tried to start my bike after it and it wouldn't start, it was turning over but just wouldn't fire up, then it sounded like it was backfiring Battery got drained so I just fully charged it and same is happening - turning over but not firing up!. An engine backfire is an explosion produced by an internal combustion engine. This causes hotter exhaust gas temps. I have a 2003 Volusia. My wife's 2005 FLHTCUSE2 began to develop problems a few weeks ago. But there are dogs. The left runs great but the right putt-putts back through so it isn't a carb issue. Re: Backfiring in Amal Concentric Carb #93315 06/27/06 10:09 am. There are multiple ways to stop a motorcycle from backfiring that vary from inspecting and properly maintaining certain parts of a motorcycle to adding or replacing specific fluids. The idle will reduce a bit if you hit a winner. If the engine responds quickly with a gratifying blast and no backfiring through the carburetor, you have your idle mixture right. Works in two-stroke, four-stroke and Diesel engines. Here's the scoop. The other 3 carb bodies have pressed in brass plugs in that location. Hey guys, I could use some help I have 2006 Vulcan 5000 with just over 3000 miles on it I bought it used in August and the only issues Ive had with it have been the battery (my fault) and running out of gas (my fault again, hush). I can wait it out or floor it and it will stop. From your question as to "where to pour gas into carb?" is concerned, it almost sounds like you may not have the experience to understand just how dangerous this act COULD BE to your health and property if not done "properly" and with restraint. Archive Motorcycle Boulevard This thing is backfiring and spitting back through the carb when I try to start it. The airflow into the motorcycle is increased because of the difference in pipe design and other specifics, and this difference causes backfire in the exhaust. " " Carb #3 only has an opening in the carb body for the accelerator fuel path (shown below). Update!! Well guys, it wasn't the AIS making the system backfire and pop. It didn't backfire in first or second, but it did in fourth and fifth. 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. 2006 Tech Contest Winner. The use of precise holes to deliver a burnable fuel is similar to the motorcycle carburetor, thus the name. December 8, 2016 and we sometimes get a commission through purchases made through our links. Putting those pods on will change your pressure drop through the carbs, and you won't flow enough fuel to keep the fuel mixture correct hence the lean condition. True backfiring is either caused by a valve timing issue or by the ignition being so far out of proper setup that the spark plug fires when the intake valve is open and ignites the incoming air/fuel mix before the intake valve is closed. ive got a 1980 arctic cat trailcat 4000. hello all, learning more and more about this bike as time goes on. If it is backfiring through the exhaust it is running too rich. Having removed all of the component parts from the carburetor body, you should clean and inspect each one. gas cap, new Kaw. i had problems with mine and it had these same Backfiring through the Carb - Page 2 - Yamaha Raptor Forum. If these are loose and leaking air into the system, you will get the pops that you describe and no amount of cleaner or Sea Foam will fix it. Is it backfiring out the muffler or back through the carb? What do the plugs look like? Sooty black would mean the mixture is too rich. I've been able to burn old gas with no problem by using it in my truck. So No real definate cause can yet be scientificly determined. A large backfire is most likely caused by a bad spark plug or plug wire. When I bought it last January I had the carbs rebuilt by a "motorcycle mechanic" recommended by my son in law. On the 40mm Mikuni Carburetor One of the problems I've had with the Road Star is a coughing or backfiring out the carburetor through the breather. But since most of those guys are out wheeling while im stuck in my office today, see if this helps. Problem was we were in Alabama at the time the storm hit and the roads back to home were closed for a week. Depending on the engine’s fuel needs this pressure will fluctuate. Most people incorrectly call any popping sound from a motor a backfire. If the carb is out of the warranty period and no defect is determined we will estimate the possible cost of tech support or recommend literature available that may help. It only really does it when it's ridden hard though. 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. I can never keep it straight when someone says it backfires. i did that gave it a 1/4 turn is better but have to pull them again still has minor pop a real headache. We supply and fit Power Commanders , Power Vision and Dynojet kits. I've also replaced the plugs and checked that both cylinders are firing. gas cap, new Kaw. A backfire is a pop, usually followed closely by a flame out the intake of a given engine. A lean mixture leaves excess oxygen after combustion. Hi Ken, i read a similar thread you had with a guy named brian, I have a 2006 xl1200c a true 1200 not a 883 convert I bought the bike last year and put 4000mi on it last season, it ran well except for a slight popping on warm up once it was warm it ran fine. Backfiring is caused by the ignition of fuel and air in the INTAKE stream causing it to fire through the CARB. Outboard motor backfire - inclination. Covers Fuses, Lubricants, Tune-up Specs, Carburetor Specs, Float Level Specs +MORE. I know it sounds funky, but that's why I posted. Been getting a lot of backfire on deceleration with my 97 Royal Star. How to Make a Car Backfire. screamin eagle II slip ons, twin tec adjustable ignition in the nose cone, arlen ness big sucker stage 2 a/c, andrew n4 cams, screamin eagle coil, stock heads. This site is dedicated to selling OEM Kawasaki ATV parts, motorcycle parts, JetSki parts and UTV parts. But another thing I was thinking of, sometimes if I blip the throttle, it will kinda choke a little (like when an old carborator coughs back through the carb. Checked flywheel key, checked valves and cam timing good. Backfire is the perfect place to meet other motorcycle enthusiasts. Unburned air and fuel pumped into the exhaust will often be ignited by the other cylinders still burning exhaust gases. Why does it backfire thru left exhaust on 1979 triumph bonneville motorcycle? shop and look through the adds. Harley carburetor jetting should only be performed after completing the fine tuning procedure described under Performance Tuning and your Harley is still running too lean. I have a 2007 VTX 1300 Retro. Put an inline fuel filter between the fuel tank and the carb in fuel line, just cuz. Generally, there are a variety of ways it gets there, and a variety of things that can make the backfiring worse. Also the plugs look on the lean side the front very slight tan, but the rear one is completely white,does this sound like a vacum leak? My slide was drilled out bigger,but it ran ok. A properly tuned and carbureted engine will accelerate smoothly and quickly through the gears. set timing adjusted valves. Is your 2-stroke BACKFIRING? This could help Over the last month or so while everyone is getting their carts dialed in for the season, I have noticed an above-average number of posts asking about backfiring issues with Marathons, so I thought I'd throw this post together so there's a searchable solution for those with questions. Difference is amazing. This condition will increase cylinder temperature during engine operation, causing a flame to expand rapidly through an open intake valve and burn the fuel coming in, resulting in a backfire. Re: Mercury 5 hp 4 stroke backfire through carb The small four strokes are prone to float issuestake the carb apart and get the spec on float drop and float level. So No real definate cause can yet be scientificly determined. it had to be on a good 15-20 miles Smooth idle, no hiccups if you are aggressively coming of idle. Carb Tunning In this information, when Holley is used, it refers Holley style carbs, such as Quickfuel, Pro-Systems, C&S, Demon, etc. The idle will reduce a bit if you hit a winner. Thus, at higher altitudes, there is less air pressure, which means more fuel tries to go through the carburetor per weight of air, & the mixture thus gets richer. An engine backfire is an explosion produced by an internal combustion engine. Re: Backfire through carb I have pretty much given up on statically timing old engines. Because it's impossible to cover every type of motorcycle or ATV problem, we'll introduce basic diagnostic and troubleshooting techniques and concepts that you can apply to many different situations. I found that it had a blown head gasket that was leaking between the cylinders and also a stuck intake valve. Stuck it back in and played with it for a bit and it blew out again. But it was hard to start, and when I did get it running, it "pops" back out the carb and the engine stutters for a second. Flowmaster expands their already impressive selection of cat-back systems by introducing three new FlowFx products for Toyota Tacoma's. 1986 Virago XV700 backfiring from front cylinder? (newbie here, thanks for this. float may be stuck in the closed position or if carburetor equipped with a electric shut off/solenoid it could be faulty/stuck/bad connection. There can be several reasons for this. i had problems with mine and it had these same Backfiring through the Carb - Page 2 - Yamaha Raptor Forum. I put pipes on it and also did what in the V-Star community is referred to as the GAK mod, which mainly consists of rejetted the carb (Mikuni 127. com/deceleration-backfire-tuning-your-carb/ on adjus. It was indeed poorly adjusted air/fuel mixture screws. On the other hand, a strong backfire can result in serious damages like cracks in the exhaust manifold. I have seen more than one motorcycle backfire through the carb because of that--- one was a '46 knuck that burned to the ground at a gas station. I did check the butterflies during the rebuild. Stuck it back in and played with it for a bit and it blew out again. Check for proper operation and adjustment of all linkage on the carburetor. The bike is also missing and backfiring below 3. I have a B&S 310000 engine in a McCulloch Ride on Mower. I did a search and found a comment stating "If the engine backfires through the carburetor, misses, cuts out or quits running, the main jet is lean. Performance gets worse with the air filter removed. should have thought of that myself because it's something i know of but it just didn't come to mind. I even tried a 65 primary jet but them bad ass anulars just dump so much fuel that it still bogs but not when you roll into it like you described as yours does. I also pulled the plug and it was really black. Recheck valve adjustments, a valve not opening or not closing will effectively eliminate air flow through that cylinder. which ignite any unburned mixture in the exhaust pipe. Modulate the choke and see if it improves. which leaves us with fuel: I left this last because you have 2 choices really you could run like seafoam or some other fuel additive through the engine and hope it clears (luckily for me I just ran it a mile or so and whatever it was passed through the engine burned off and was no longer a problem) OR you have to strip the carb down and give it. Not complaining, lots of folks had it a lot worse. Honda motorcycle carburetors deliver a precisely metered air/fuel mixture to the engines. The photo hosting service PhotoBucket has gone psycho. If it's been more than ~3 months, you should clean out the fuel system and the carb. Normally, the mixture screw should only require 2 to 3 turns. and soaked jets, bowl and anything that I could get off the carb that the solution wouldnt eat. Generally, there are a variety of ways it gets there, and a variety of things that can make the backfiring worse. The decompressor opens up to the inlet which blows back through the carb. If it is an exhaust valve, it will backfire through the tailpipe. Is your 2-stroke BACKFIRING? This could help Over the last month or so while everyone is getting their carts dialed in for the season, I have noticed an above-average number of posts asking about backfiring issues with Marathons, so I thought I'd throw this post together so there's a searchable solution for those with questions. comA backfire that you hear in your tail pipe isA backfire back out through your intake. Not commmon, but a quirky find. We're working on a 350 SBC, we just finished putting a Holley street dominator manifold, lunati cam, and Holley 4160 750 CFM carb. Not complaining, lots of folks had it a lot worse. 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. When it backfires a smal cloud of spray comes out the carb. Covers Fuses, Lubricants, Tune-up Specs, Carburetor Specs, Float Level Specs +MORE. Ask the seller when it last ran. If I crank it for a while with the throttle twisted all the way open, it will backfire through the exhaust. We supply and fit Power Commanders , Power Vision and Dynojet kits. You'll find ratbikes, cafe racers, vintage bikes, Harleys, scooters, crusiers, hot rod bikes, moto X, standard bikes, adventure bikes, bobbers, baggers and MXRs -- just about everything. I got it back and every once in a while when applying throttle from idle to take off or go around a vehicle, it will backfire back through the carb. 1) Keep a Check on the Carburetor. I have a 98 Harley Heritage Custom with the 80CI EVO. Almost all backfire situations will have other symptoms attached to them such as a Check Engine Light illuminated. 002 on the other. The easiest thing is to go through the exhaust system and check for loose nuts on both the exhaust pipe and the manifold on the cylinders. Archive Motorcycle Boulevard This thing is backfiring and spitting back through the carb when I try to start it. Recheck valve adjustments, a valve not opening or not closing will effectively eliminate air flow through that cylinder. It almost sounds like a compression stroke that isn't igniting and backflowing through the intake. A "backfire" is when fire comes back through the intake-valve and into the carburetor you have to have a *seriously* lean condition to create an actual "backfire" - I have a burnt-down set of carburetors and some holey air-filters as a result of a nitrous-induced "backfire". It has a Mikuni HSR42 carb on it that backfires through the carb quite frequently. Carb Tunning In this information, when Holley is used, it refers Holley style carbs, such as Quickfuel, Pro-Systems, C&S, Demon, etc. I have removed and cleaned all jets in the carb, put in a new piston and honed the bore, it has good compression, new correct specification spark plug. The backfiring of the motorcycle is a signal that something isn't quite right. Even replugged the air/gas mix screw access hole (chewing gum) because the dealer told me that it could be sucking a little wind through there. Power valve blown out by spitback up through carb. We also help keep your Yamaha motorcycle or Yamaha ATV running like new by providing maintenance and how-to videos, our Cheap Tip Blog, and product install/review videos and blog posts. Needle in primary carb was in 3rd nocth from the top (out of 5), now is in 5th notch and engine runs much better. Flowmaster expands their already impressive selection of cat-back systems by introducing three new FlowFx products for Toyota Tacoma's. Besides possibly causing you engine to ping and to run hot and to run on after shut down, the left over oxygen can combine pyro-chemically with the aluminum in the pistons, burning holes through them in places where you'd rather it didn't. Whatever the motorcycle or automobile, most carbs work on the same principles and internal systems to deliver fuel in the proper mixture ratio to the engine. Ran the crankcase vent hose through that hole (just to plug up the hole) and capped it (the manual says to plug it onto one of the bolts holding the carb, but my bolt doesn't stick out like in the manual diagram). 99 We specialize in custom aftermarket Honda bobber parts. Good morning fellow riders, My 02 Vulcan 800 custom during warm up coughs and pops through the carburetor. - backfires/pops at idle through the front cylinder exhaust and occasionally front cylinder carbs. A backfire is a sign that your car isn't running efficiently and needs to be addressed in short order. I've been able to burn old gas with no problem by using it in my truck. ie loads of spark but no gasoline. hello all, learning more and more about this bike as time goes on. First off, is it really backfiring through the carb? True backfiring, especially on bikes with electronic ignition, is very rare. Use the carburetor cleaner to blast out the air and fuel gallies in the carburetor body. On the way home her Harley started to misfire and run poorly. There are several ways to prevent backfires. Popping out the exhaust could be most anything, but if you're way too rich that can happen as well. Best Answer: The same thing that causes backfiring on a car or any other vehicle or object that uses an internal combustion engine: running too rich - unburned fuel in the exhaust timing too far advanced low fuel pressure/lean fuel:air ratio can cause a backfiring through the carburetor (if equipped). 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). Deceleration Backfire is caused by fuel burning in the exhaust manifold or header. Needle in primary carb was in 3rd nocth from the top (out of 5), now is in 5th notch and engine runs much better. I still use my timing light just to make sure I am close to the factory setting. I replaced the fuel and vacuum lines and fuel filter thinking there might be a vacuum leak because the hoses on the intake were almost ready to fall off!!. * I drained the carby again and put in another new spark plug (as advised by Mobile Motorcycle Medic)= still no start, no change at all. My Bike Backfires During De-Acceleration After I Installed Aftermarket Exhaust. When you say backfire do you mean a "real" back fire as in through the carb and into the airbox A the more "normal" back fire of the Bang out the exhaust pipe? The "smog pump" Is an air injection system that injects fresh air into the exhaust tract after the exhaust valve. I bet you've wetted them now. Any time the exhaust is “opened up” the condition of deceleration pops is MUCH more noticeable and problematic. So when going through a village at around 35-40 mph, in a gear that keeps me just above 2000 rpms, if I stay on that gear a for a steady period of some 30 seconds to a minute, I have about a 25% chance of hearing a nice pop as I accelerate out of that village during the next gear change. The motorcycle carburetor is a very touchy device that can cause all kinds of trouble if mishandled or neglected. If the engine tends to backfire while accelerating you might have a bad carburetor accelerator pump. Visit my website at The Carb Spa Click on the logo for more links!!!: If you are browsing as a Guest you are only seeing a portion of the information available! If you want full access please sign up for free as a full member at V4MB - there are never any charges! Click ** HERE ** to be referred by me. The seller also had the carbs professionally gone through, adjusted the valves, added a new Vance & Hines header and a new element for the original airbox, new Kaw. but still does this. Why dose engine backfire through the carb My Honda VT1100 saber started popping through the rear cylinder carb. Blip the throttle a time or two and observe the results. I've had two instances recently of backfires through the carburettor causing fires. It backfires through the pipe as unburnt fuel detonates in the hot exhaust. set timing adjusted valves. Modulate the choke and see if it improves. The backfire is more than likely excess oil igniting in the combustion chamber of the blown head gasket side. One of the cures is to decrease amount of fuel injected by the accelerator pump when first opening the throttle. Now, I can't even get the backfire, and what I'm getting after kicking my freakin ass off, is a big COUGH through the carb and a puff of white smoke. I lost sight of her so I pulled over. Fitted a brand new spark plug which seemed to fix the backfiring - it started after a couple of kicks, the engine didn't backfire but it didn't run crisp either and was bogging down (which I put down to using too much oil in the cylinder when rebuilding the engine) took if for a spin after about two minutes it cuts clean out. I'm starting with the most recent and working backwards. Instead of tuning and messing with it I bought a used one off a running cabriolet. I put pipes on it and also did what in the V-Star community is referred to as the GAK mod, which mainly consists of rejetted the carb (Mikuni 127. As well, you smell a sharp odor from the exhaust as it is pulled through the motor and undergoes combustion. What's it mean when a bike "backfires" through the carb? A little repair work and so far it is lookin really good. 1 - The original backfire issue came out of nowhere. While looking around I noticed that the gap on the ignition coil was. Joined: Jul 15, 2015 motorcycle backfires at mid throttle. I have a mild mannered 1955 CB34, small port, flat topped piston, non racing,mag/dyno, Monobloc carbed Gold Star. We also help keep your Yamaha motorcycle or Yamaha ATV running like new by providing maintenance and how-to videos, our Cheap Tip Blog, and product install/review videos and blog posts. "What Causes Backfire Motorcycle? Watch more videos for more knowledge How to make a motorcycle backfire! - YouTube https://www. Our commitment to providing the best parts at the best prices is topped only by our dedication to providing the very best service to our clients. I was told the battery is probably on its last legs and it hasn't been ridden for days and before that probably not regularly for ages. Practically every motorcycle enthusiast in the world loves and admires the Harley Davidson brand of motorcycle. when i got it, of course the carbs were dirty and the bike had been sitting for a few years. Why does my engine spit or backfire? First off, you need to determine whether it is backfiring out the exhaust or back up through the carb. There are many ways to stop the bike from backfiring and some of them are as listed below. First off what causes this? Secondly is this bad for the engine or exhaust system? I have noticed that I can adjust the choke to avoid this however the bike. This site is dedicated to selling OEM Kawasaki ATV parts, motorcycle parts, JetSki parts and UTV parts. There are a few reasons why your motorcycle to go through a Exhaust backfire, popping when letting off throttle - Motorcycle Forum 26 Apr 2009 - 28 pesan - ‎17 penulis Exhaust backfire, popping when letting off throttle General. it doesn't backfire now, it was a problem with a new carb and the e-clip on the needle was on the bottom notch. But it was hard to start, and when I did get it running, it "pops" back out the carb and the engine stutters for a second. I am familiar with those carbs as I have similar ones on my Kat. If your motorcycle has sat for a long time then make sure you take off the carburetor and give it a good clean so you don't have to deal with all the problems that accompany a dirty carb. If backfiring occurs through the carburetor then adjust the idle mixture screw out another 1/8 to 1/4 turn. Backfiring is dangerous and it caused by incorrect valve timing or ignition timing. When an exhaust pipe is changed, this causes an unbalanced air-to-fuel ratio. Try a little spray of carb clean in the carburetor with the throttle open, then crank it. “My motorcycle won’t start!” Ask the phone-jockey of your local motorcycle shop or dealership how many times a day they hear those words. I rebuilt a motorcycle once that had the same problem. vacuum hoses can also encourage backfiring. This can be fixed by adjusting the carburetor for a richer mixture - consult your owners' manual or have a professional adjust it. but still does this. 2k Views The "Poor Man's" Carb Adjustment Sometimes, you can get lucky and a simple can of carb cleaner works magic. On the theory that most fueling problems are really ignition problems, I installed a Boyer system with 6v coils. Why does my engine spit or backfire? First off, you need to determine whether it is backfiring out the exhaust or back up through the carb. yes I received notice from Canadian Post back through USPS that they damaged your package, so I shipped a new one. float may be stuck in the closed position or if carburetor equipped with a electric shut off/solenoid it could be faulty/stuck/bad connection. I replaced the carbs and it is still backfiring through the RHC carb. Sounds to me like it's misfiring part of the time, and the resultant unburned fuel being passed is later igniting downstream, in the exhaust system - causing the "sloppy, farty" sound, backfiring and red-hot exhaust pipe. Maybe a bad carb to intake gasket. I rebuilt a motorcycle once that had the same problem. Basically keep increasing pilot jet size until fuel screw wants to be at 2 turns out for peak RPM during adjustment. Why dose engine backfire through the carb My Honda VT1100 saber started popping through the rear cylinder carb. Needle in primary carb was in 3rd nocth from the top (out of 5), now is in 5th notch and engine runs much better. I can wait it out or floor it and it will stop. The circumstances were over priming either because I forgot the correct starting sequence, or I was turning the engine over by hand while checking valve clearances. The point gap for both is. Buy Suzuki LTA400 LTA 400 Eiger 4x4 ATV Quad Carburetor Carb Stage 1-7 Jet Kit: Jets & Jet Kits - Amazon. Your fuel pump may not be working well. Good morning fellow riders, My 02 Vulcan 800 custom during warm up coughs and pops through the carburetor. Re: Deceleration Popping explained I am glad I read this, As you can see in my signature that I have a 91 XR250R. screamin eagle II slip ons, twin tec adjustable ignition in the nose cone, arlen ness big sucker stage 2 a/c, andrew n4 cams, screamin eagle coil, stock heads. Maybe having the float sit overnight in that concentrate fuel mix loosened it up? I've bunned about 2. Works in two-stroke, four-stroke and Diesel engines. The backfire is more than likely excess oil igniting in the combustion chamber of the blown head gasket side. What would cause an '82 Jeep 258 6 cylinder to backfire through the exhaust when I shut off the engine? on side of carb this closes throttle plate when ign is. I had the float level at the low end (19. sorry for the late reply was on holidays. Most engines have one or two of these valves one for each exhaust manifold. How to measure the carburetor body to determine what size CV diaphragm you need and if JBM Industries has a part that might fit your vintage motorcycle. The motorcycle carburetor is a very touchy device that can cause all kinds of trouble if mishandled or neglected. Rc backfire exhaust kit - emit. But, it would not rev cleanly, and was backfiring through the exhaust. petcock, etc. Just bought the bike and everything on the bike is still stock other than minor accessories. 1 - The original backfire issue came out of nowhere. Mixture tuning on your Harley Davidson CV carburetor is a simple procedure that can easily be performed with basic tools. I also pulled the plug and it was really black. If the engine tends to backfire while accelerating you might have a bad carburetor accelerator pump. Re: Mercury 5 hp 4 stroke backfire through carb The small four strokes are prone to float issuestake the carb apart and get the spec on float drop and float level. The only thing which could cause the popping through the carb would be a mistimed firing of the plug or a valve train problem (weak or broken spring, valve not sealing or cam lobe problem). I only taking a guess here. What gives? and what could they have done to make it so sluggish and popping back through the carb????. The use of precise holes to deliver a burnable fuel is similar to the motorcycle carburetor, thus the name. I have a 2007 VTX 1300 Retro. Mine also for the first 5 minutes of operation has a tendency to backfire in the carb/air cleaner after you throttle down to engine idle to coast and then slowly throttle back up to accelerate. Everything is stock on the bike other than Vance and Hines long shots and a K&N air filter. These intrepid women share their tips to help you plan your own motorcycle adventure. I reset the valve clearances, checked the static ignition timing and carb settings. I have changed the spark plugs and just tonight I finished adjusting the valves. August 9, 2006 1. It almost sounds like a compression stroke that isn't igniting and backflowing through the intake. Popping through the exhaust on acceleration. The use of precise holes to deliver a burnable fuel is similar to the motorcycle carburetor, thus the name. Maybe having the float sit overnight in that concentrate fuel mix loosened it up? I've bunned about 2. What would cause this? It also seemed a little stumbly from low rpm's. With out the air cleaner tube off I can see fire popping back through the carp at higher rpm. any common jetting size pms etc for this issue would be appreciated. Any thoughts?. Usually when i am idling and give it a little blurp of the throttle, or lugging the bike between 1200 and 2000 rpms, this 1 carb seems to backfire up it into the air box, i have completley cleaned the carbs, by taking them apart, and by the shotgun method, adjusted the air screws and synced them a few times, and they all seem to be perfect, i. , while the engine is running or while shutting down. Hi folks! The last few days, my KMD 150 GY6 would start dying at intersections and give an every-now-and-then backfire. 2k Views The "Poor Man's" Carb Adjustment Sometimes, you can get lucky and a simple can of carb cleaner works magic. screamin eagle II slip ons, twin tec adjustable ignition in the nose cone, arlen ness big sucker stage 2 a/c, andrew n4 cams, screamin eagle coil, stock heads. Ran the crankcase vent hose through that hole (just to plug up the hole) and capped it (the manual says to plug it onto one of the bolts holding the carb, but my bolt doesn't stick out like in the manual diagram). The valves are adjusted too tight. The next day it wouldn't start - just got a cracking backfire thru the carb. range during deceleration, then most likely the injectors are not turning off as intended, and this indicates a possible issue with the fuel injection system. This only happens at cranking speeds. Deceleration back-fire, rough idle, and throttle lag can be quickly adjusted by tuning your carburetor. Just because you can smell gasoline or the plugs are wet, does not mean there is fuel getting to the carb. A lean mixture leaves excess oxygen after combustion. Basically keep increasing pilot jet size until fuel screw wants to be at 2 turns out for peak RPM during adjustment. The following articles and instructions are provided as general information for enthusiasts working with AMAL carbs on British Motorcycles, without the need for expensive tools or paying for expensive shop labour. 1 - The original backfire issue came out of nowhere. its a 883 with a 1250 big bore kit. Check for cracked or stiff bending hoses and replace if necessary. under hard accel at night there is small flames at times. Question: Backfire means thorough the carbsAfterfire is through the exhaust. Randakk's Master GL1100 Carb Overhaul Kit even includes an extra spare for this O-ring which often lost or misplaced. Hello all, I have read an read all your tech stories so I took it among myself to do just about what they all said,. Usually when i am idling and give it a little blurp of the throttle, or lugging the bike between 1200 and 2000 rpms, this 1 carb seems to backfire up it into the air box, i have completley cleaned the carbs, by taking them apart, and by the shotgun method, adjusted the air screws and synced them a few times, and they all seem to be perfect, i. Now, I can't even get the backfire, and what I'm getting after kicking my freakin ass off, is a big COUGH through the carb and a puff of white smoke. Recently I removed the rear wheel from my motorcycle and had to exert pressure on the front pipe in order to extract the axle bolt. The primary cause of a backfire is decelerating too quickly. Fresh air is drawn in through those tiny holes and provides sufficient oxygen to ignite the unburnt gases inside. Even if its on a intake stroke they spark together thats where the backfire is coming from. 5k but smoothes out and has good power after that.