Still Back Fires - Kawasaki Vulcan 750 Forum : Kawasaki VN750 Forums
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post #1 of 14 (permalink) Old 03-31-2007, 08:44 AM Thread Starter
 
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Still Back Fires

Hey all. I have a tread asking about backfiring when trying to start hot. I did everything everyone offered but still have the problem. I have checked the verses but no dice. Anyone have any other idea's why this is happening? anyone know anything about the timing? it seems to catch like the timing is out whenever you try to start it.
I t does ride and I have been and IT'S GREAT! but I really need to get the backfire thing fixed. Thanx all for your help!
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post #2 of 14 (permalink) Old 03-31-2007, 09:09 AM
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What condition is your battery in?. When hot starting with an older battery, fuel will build up in the cylinders because the battery doesnt have enough juice to create a hot spark. When It does spark, all that fuel explodes, hence the backfire.
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post #3 of 14 (permalink) Old 04-01-2007, 11:14 AM Thread Starter
 
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I have put in new plugs and battery, same problem. still looking for other problems that might cause it.
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post #4 of 14 (permalink) Old 04-01-2007, 11:27 AM
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How are you starting the bike?
Cold start is full to partial choke, no throttle.
Hot start should be no choke and just a blip of throttle to catch it.

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post #5 of 14 (permalink) Old 04-01-2007, 10:47 PM Thread Starter
 
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Thats the way I have been doing it. I had some friends tell me the carbs need to be adjusted. Any suggestions on that?
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post #6 of 14 (permalink) Old 04-02-2007, 05:37 AM
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Start out by adjusting the Air/fuel mixture screws on the carbs. Turn them all the way in, but dont over tighten (till snug). Then turn the screws out 1 3/4 turns out. I really dont know the engine well. Can it be a timing issue maybe?
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post #7 of 14 (permalink) Old 04-02-2007, 10:53 PM
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Have you checked for air leaks? Examine the carb boots and make sure they are on tight.

Have you tried marbling? this does not always help the "popping issue" but you may have a fault in the "clean air system" that is letting air in.
You say you put in new plugs and a battery? What type of plugs and was it a MF glass matt battery???

Also need to know...

What do your plugs look like?

How old is the bike, how many miles? Is it still all stock?
Have you examined the airbox and airfilters?

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Last edited by Knifemaker; 04-02-2007 at 10:55 PM.
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post #8 of 14 (permalink) Old 04-06-2007, 11:36 AM
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Weak spark can cause unburnt fuel to hit fresh air and ignite with a boom. Weak spark can be caused by coil wiring being weak from old wiring or corroded connectors. It can also be caused by an overheated R/R. Once I moved my r/r to a cooler location, my backfiring and hard hot starting went away.

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post #9 of 14 (permalink) Old 04-07-2007, 09:11 AM Thread Starter
 
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I have a guy that says he knows what the problem is and how to fix it. says it is either the carbs or timing. It has not been too bad though only a couple of times it has backfired and it was great to ride, too bad winter has returned
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post #10 of 14 (permalink) Old 04-07-2007, 09:15 AM Thread Starter
 
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Quote:
Originally Posted by Knifemaker View Post
Have you checked for air leaks? Examine the carb boots and make sure they are on tight.

Have you tried marbling? this does not always help the "popping issue" but you may have a fault in the "clean air system" that is letting air in.
You say you put in new plugs and a battery? What type of plugs and was it a MF glass matt battery???

Also need to know...

What do your plugs look like?

How old is the bike, how many miles? Is it still all stock?
Have you examined the airbox and airfilters?

KM

new plug, battery,gas,ect. It's a 86' not original. the guy that is going to check it out is going to check all the items you are talking about and more. So hopefully, I can ride when the nice weather returns IF the nice weather returns. Dang gas is 2.79 now I hate cars!!

tell me more of this marbling. I have not tried or heard of it.
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