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Discussion Starter #1
Alright, im a noob to bikes so just bare with me :).. i got a F3 that turns over but doesnt start. Since the bike was sitting around for over a year i decided to clean the carbs. After that i tried starting but same thing, crank but no start. i then check if there was spark from the plugs, took it out regap them and crank (with the plugs out and grounding it to the chassis). seems like there is spark but its weak during crank but once i let go of the start switch it looks to me the spark was significantly stronger. I then checked the power to the coil packs. hooked up a volt meter to the power and ground wire(in the Volt scale) nd cranked it. the weird thing was, there seem to be no power going to but once i let go of the start switch the voltage seems to jump up for about a second or two before it goes back down to zero. since i dont have a spare coilpack i went on into checking if there was fuel going into the engine. so i hooked up 12v to the fuel pump, it works but seems kinda weak, but still sucked in fuel no problem. so i started it again a couple times, it seems like it almost caught on but it didnt want to start it. once we let go of the start switch, it made a loud backfire.

so i guess my question now is.. seems like there is fuel going into the engine but is having a delayed/weak spark. since the voltage spiked only happends once we let go of the start switch, could it be the coils are bad? or somewhere before the coils? :idunno: any help is appreciated. thanks :)
 

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I can't over emphasize the importance of a good strong fresh battery. It is true cranking is a big draw and lowers available voltage to the coils causing a weaker spark. A lot of slow cranking can result in a flooded engine.
 

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Discussion Starter #3
yea im picking up a new battery in a couple days. but when i checked nd start everything before, i used a fully charged jumper battery for cars. Started my parents V-8 no prob so for a bike it shouldnt be a problem rite? :(
 

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The car battery is fine but because it has so much available cranking power, you could burn out your small starter. No point cranking and cranking if it's not starting. You may consider replacing your spark plugs if they have been soaked with fuel. Even after drying they can't fire properly under cylinder pressure.
 

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There is no such thing as "too much power" available to the starter, voltage drop below 9 volts can and will cause it to pull too much current and fry it, but as long as cranking voltage remains from about 9.5 to 13.1, the battery will only pull as much current as it needs. Now you CAN overwork/overheat the starter trying to crank a motor that won't fire, especially with a good hot battery. No more than about 20~30 seconds cranking, and at least 2 minutes to cool down before attempting to crank it again. :cool:
 

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I was pretty sure that's what you meant, and wasn't disagreeing with you, I just wanted the OP to fully understand the dynamics of the situation. :cool:
I also agree with replacing the spark plugs if there is any doubt, :cool:
 

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Discussion Starter #8
anyways just thought id share that it was the coils that were bad. swapped them out and everything ran perfectly nd smoothly. :)
 
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