will not start/backfiring - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 27 (permalink) Old 11-05-2010, 08:06 AM Thread Starter
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Exclamation will not start/backfiring

Guys me an my buddy are fixing his bike, we took the carbs out to clean them up due to a sticking bowl, got that taken care of, also cleaned up the jets as they were cloged up, but the bike won't start, when we crank all it does is give us is a super loud bang thru the exhaust and also give us a mild one thu the carbs, we have a new battery on the bike hooked up to a chargers to ensure sufficient voltage/amps to achieve proper cranking speed, any ideas???
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post #2 of 27 (permalink) Old 11-05-2010, 10:14 AM
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How did you clean the jets? If you poked anything through them you probably damaged the orrifice. Means you'll need to replace them.
No other thoughts right now, I'll think about it at work.
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post #3 of 27 (permalink) Old 11-05-2010, 02:19 PM
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Mine was doing this same thing. I think all I did was put in Iridium plugs and then an AGM battery after that... I think the plugs made it start even if it took a little bit of cranking... and the AGM battery made it start as soon as you pushed the button.

All of which points to spark, so check everything that has to do with spark. Even before the Iridium spark plugs I thought I had good spark but it still didn't start. Those plugs made a lot of difference. You should check for spark first though, maybe check that the coils are getting enough voltage and check your spark plug wires and all.
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post #4 of 27 (permalink) Old 11-05-2010, 03:58 PM
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REBUILD your starter, it's grabbing too many amps....


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post #5 of 27 (permalink) Old 11-05-2010, 05:21 PM
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All good suggestins above.

Fergy`s ignition coil mod, taking primary voltage directly from the battery, may help you too.


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post #6 of 27 (permalink) Old 11-05-2010, 06:02 PM
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You didn't mention how old the bike is, or if it has had a tough life, lived mostly outside etc. If you're cranking the engine with a wet cell battery, it might not have enough juice to overcome the old and weak wiring. Check all the above and see if you can get your hands on an AGM battery. You'll need it.

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post #7 of 27 (permalink) Old 11-05-2010, 06:15 PM Thread Starter
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Guys, I'm not sure of what kind of battery this is, but I know it is new, the bike is a 1995,the jets look good w/o damage, and just to justify buying a new starter...why would the starter be the issue??? and and why do I need a new battery??? along with iridium spark plugs??? the bike is a 1995... bike has been kept inside of the garage, also I checked spark with a spark tester and it shows a spark jumping about a 7/16 gap.

Last edited by nicknack2; 11-05-2010 at 06:18 PM.
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post #8 of 27 (permalink) Old 11-05-2010, 06:24 PM
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Originally Posted by nicknack2 View Post
why do I need a new battery??? along with iridium spark plugs???
Until you've experienced it, mere words fall short of adequately explaining the difference. The AGM battery has more amps, is no maintenance (no pulling the seat every week to check electrolyte levels), and won't leak acid over your electronics and frame. The iridium plugs, while initially pricey, last for 100,000 miles or more and are virtually lifetime plugs. Get both and your bike will start if the air fuel mixture is correct.

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post #9 of 27 (permalink) Old 11-05-2010, 06:37 PM Thread Starter
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I understand the easiness of having lifetime plugs and 0-maintenance battery, but how does that relates to the backfiring, I'm not worried about the no start-the air/fuel mixure at this time, my main concern right at this time is why is it back firing, it appears as if it was out of timing...
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post #10 of 27 (permalink) Old 11-05-2010, 08:47 PM
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Is the choke working properly? Are the plugs getting all wet after cranking the engine over for awhile? These carbs are really tempermetal about just a little dirt getting into them. Is the fuel tank nice and clean? Maybe the fuel petcock is cloged or not working properly. It works on vacuum, check for crakes in the vacuum line.

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