I have a 2003 H-D Sportster 883 XLH and today I was riding for about an hour and a half and then the bike started backfiring and sputtering and then the bike quit on me. It wouldn't start back up but atfter about 30 minutes, it started back up and ran OK and then after riding it some more, the same thing happened. We looked at the spark plugs and they looked fine and we looked at the fuses and they looked fine, too. We checked to see if there were any loose connections and we didn't see any.
There are two things that can cause what you describe: Lack of fuel, and lack of spark.
The easy way to eliminate is put an extra spark plug in your pocket....Ride the bike until it quits, then pull one plug wire, plug in your spark plug and hold the base of it against the block, and crank the engine, while observing the plug.
If you have spark, fuel flow issue is likely, check all filters, and strainers (in tank too). You can pull the fuel line and open the fuel valve and observe flow, but be careful of spark and fire, happens EASILY.
If you do not have spark, investigate the ignition system, if electronic, you can be overheating, usually requiring component replacement.
Wasted spark ignition, probably not firing on power stroke but firing unburned fuel on exhaust stroke which would cause the backfire.. Replace plugs even if they LOOK good or spark outside the engine and not under compression pressure. After that could also, but less likely, be poor secondary cable(s).
John
SOURCE: Bike stalls in high gears when cruising around 45-50MPH
Could be your spark plugs, or maybe your side stand as some bikes if not all of them now have a switch on the side stand which prevents the rider from starting the bike if the stand is extended. So if the spring which retracts the stand is slightly lose, it pulls on the switch and cuts off power. Im not an expert but just check these.
Could also be that your carbs are dirty. So just give them a bit of a service and check for any blockages in there.
SOURCE: When bike gets worm it runs like ****
Since you have thrown the entire ignition system at it, let's think about fuel. If you were running out of gas it would act as you described. I would start by removing the float bowl. Be careful not to spill any gas because we want to look at the level. It should be over half full. Check the float movement. You should be able to push it up without resistance. Looking from the bottom remove the phillips screw that retains the float axle and the float and needle valve should fall out. If the needle valve has three sides or if the rubber tip is worn, replace it. The 3 sided valves have a tendancy to stick closed and all dealer stock should be the 4 sided version by now. After you re-install the float, leave the bowl off and follow the small vacuum hose from the petcock to the carb. Pull it off at the carb end. Look to make sure it isn't damaged. **** lightly (sorry) or use a vacuum pump on the hose. With the petcock on and gas in the tank, a healthy stream of fuel should pour from the needle valve. If not, the petcock diapragm is shot. If none of this helps, take it for a ride and when it acts up, crack the fuel cap loose and if it takes off the vent in the cap is malfunctioning.
SOURCE: 04 sportster 883 will turn over and back fire but will not start
Sounds like it jumped time.. Check your timing ..
SOURCE: My 2003 sportster 1200 sputtered this morning and
Sounds like it ran out of gas. Yeah, and I bet the fuel tank is full. Reach under the fuel tank to the petcock and pull the fuel line off. If you've still got the vacuum operated petcock, no fuel should flow out. But, if you try to start the engine, the vacuum should open the petcock and allow fuel to flow to the carb. Press the start button and watch for fuel to run out, catch the fuel in some sort of container.
If no fuel runs out, you've got a bad petcock. I've seen this at least a hundred times. Those petcocks are the worst thing Harley ever did in my opinion. You can take the petcock out of the tank, disassemble it and look for a hole in the diaphragm or you can replace it with a high quality manually operated petcock. I recommend a Pingle. They're pricey but well worth the money.
To check your diaphragm, take the four small screws out of the back of the petcock. Remove the plate watching for the small spring and needle thats under the plate. Hold the diaphragm up to the light and gently stretch it and look for a hole. If you find a hole, buy a replacement diaphragm at your local Harley dealer and reassemble your petcock.
Hopefully, this will help you fix your problem. If not, write back and give me some more information.
Good Luck
steve
Testimonial: "This was the problem! Fixed it last night and it is running great! Thanks!!!"
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