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Backfire through intake during cranking

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Old 12-07-2014, 11:20 PM
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Default Backfire through intake during cranking

Been getting this issue more frequently. Sometimes during cranking, cold or hot doesn't matter, my 103 will backfire through the intake. It usually starts up just fine after that. I've had off and on cranking issues with this bike since I got it. Sometimes it fires up in 1 second, other times it will take 3-4 seconds of cranking. Totally random, I never know what it's going to do when I hit the starter.

I'm thinking the backfiring may be related to my battery being a little weak because it tends to happen more when it seems that the battery is struggling to turn the motor.

Before you start thinking lean mixture, don't...I've actually added 10% more fuel during cranking with my PV to see if it would help the random starting issues. So far it hasn't.
 
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Old 12-08-2014, 04:25 PM
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Originally Posted by Red Dragons
Been getting this issue more frequently. Sometimes during cranking, cold or hot doesn't matter, my 103 will backfire through the intake. It usually starts up just fine after that. I've had off and on cranking issues with this bike since I got it. Sometimes it fires up in 1 second, other times it will take 3-4 seconds of cranking. Totally random, I never know what it's going to do when I hit the starter.

I'm thinking the backfiring may be related to my battery being a little weak because it tends to happen more when it seems that the battery is struggling to turn the motor.

Before you start thinking lean mixture, don't...I've actually added 10% more fuel during cranking with my PV to see if it would help the random starting issues. So far it hasn't.

A neighbor had this problem "all the time" on his 13 RK. When I went riding with him, I saw that most of the times it was because he wasn't holding down the starter button long enough. He'd let off of it as soon as he "thought" the bike was going to run.

Now, he just holds it in until it's running. Since that time, he hasn't had any problems. Not saying this is your cause, just a thought.
 
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Old 12-08-2014, 05:02 PM
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Is it kicking back when it first starts cranking? What kind of voltage on the battery?
 
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Old 12-08-2014, 05:20 PM
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Originally Posted by FinalShot
A neighbor had this problem "all the time" on his 13 RK. When I went riding with him, I saw that most of the times it was because he wasn't holding down the starter button long enough. He'd let off of it as soon as he "thought" the bike was going to run.

Now, he just holds it in until it's running. Since that time, he hasn't had any problems. Not saying this is your cause, just a thought.
Yeah I always hold it til it starts.


Originally Posted by Harleycruiser
Is it kicking back when it first starts cranking? What kind of voltage on the battery?
Doesn't kick back but like I said it seems like the battery is having a hard time turning it over at times. Voltage is normal about 12.4 at rest. Not sure what it drops to during cranking.
 
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Old 12-08-2014, 06:36 PM
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Originally Posted by Red Dragons
Yeah I always hold it til it starts.




Doesn't kick back but like I said it seems like the battery is having a hard time turning it over at times. Voltage is normal about 12.4 at rest. Not sure what it drops to during cranking.
12.4 is getting weak, that is when I start thinking about a new battery. Low voltage, slow starting can fry a starter.
 
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Old 12-08-2014, 06:47 PM
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Originally Posted by Harleycruiser
12.4 is getting weak, that is when I start thinking about a new battery. Low voltage, slow starting can fry a starter.
Yeah, the damn battery is only 2 years old though.
 
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Old 12-08-2014, 06:54 PM
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Battery connections, battery, or call Fuelmoto with what it's doing. There are issues with some tuners on cold crank. A bad compensator can cause this also, but I wouldn't expect this on a 2013 low mileage bike.
 
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Old 12-08-2014, 08:20 PM
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Originally Posted by checkers
Battery connections, battery, or call Fuelmoto with what it's doing. There are issues with some tuners on cold crank. A bad compensator can cause this also, but I wouldn't expect this on a 2013 low mileage bike.
Roger that.
 
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Old 12-09-2014, 12:56 AM
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Originally Posted by Red Dragons
Been getting this issue more frequently. Sometimes during cranking, cold or hot doesn't matter, my 103 will backfire through the intake. It usually starts up just fine after that. I've had off and on cranking issues with this bike since I got it. Sometimes it fires up in 1 second, other times it will take 3-4 seconds of cranking. Totally random, I never know what it's going to do when I hit the starter.

I'm thinking the backfiring may be related to my battery being a little weak because it tends to happen more when it seems that the battery is struggling to turn the motor.

Before you start thinking lean mixture, don't...I've actually added 10% more fuel during cranking with my PV to see if it would help the random starting issues. So far it hasn't.
The Dyna's for some reason have very rich starting circuits. Richening it up can only make it worse at some time. Drop the fuel under the cranking fuel 3.0 on each setting from the stock setting and not from the one where you are now. Attached a screen clip of where the cranking fuel should be. If you want send me a PM with your email and info on bike and I will send you a map to try.
 
Attached Thumbnails Backfire through intake during cranking-13-dyna-new-cranking-fuel-table.jpg  
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Old 12-09-2014, 01:06 AM
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Originally Posted by ke5rbd
The Dyna's for some reason have very rich starting circuits. Richening it up can only make it worse at some time. Drop the fuel under the cranking fuel 3.0 on each setting from the stock setting and not from the one where you are now. Attached a screen clip of where the cranking fuel should be. If you want send me a PM with your email and info on bike and I will send you a map to try.
Interesting, I've never heard this before. Don't mind me asking where you got this information.
 


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