[crzychrs]

my 86 vn750 will not rev up in neutral, it idles fine but when i give it a little roll on it sputters and misses. put it in gear and all is well. I dont get it. some emissions parts have been removed by previous owner. Also the battery will not charge, when running all electrical functions seen to be powered properly, lights not dim ect. but the battery doesn't seem to be receiving any power. any ideas,

 

[slimvulcanrider]

whats the voltage at when you rev it... stock charging system doesn't start charging until about 2000 rpm... and doesn't put out full charge till 4500 rpm. With that being said, make sure the battery is fully charged to 12.5-13.0 volts, and all the grounds are tight. Also you might have fuel issues, but with out further information kind of hard to tell which way to go.

 

[Spencer1]

X2 I suspect he's checking voltage at idol and and has a carb problem.

 

[Big Nick]

Key.

How does the key feel in the ignition, if it's sloppy and loose, it could be the contacts in the base of the switch.

 

[crzychrs]

voltage unknown, i do not have a voltage meter,i will get one and check,as for the key it is a little loose and hard to turn sometimes. Thanks all

 

[slimvulcanrider]

voltage unknown, i do not have a voltage meter,i will get one and check,as for the key it is a little loose and hard to turn sometimes. Thanks all

Unknown voltage? How do you know its not charging?

 

[crzychrs]

I know it is not charging because new battery at full charge will only start it a few times before dead, even after riding for hours. Charge it up and same thing, headligh is bright when bike is running even wuth dead battery

 

[slimvulcanrider]

doesn't sound like a bad battery, sounds like poor grounds... or poor connection on the starter solenoid. I have also seen dirty ignition switches and starter buttons cause hard starts and no starts with out a super charged battery.

does your headlight come on when the keyis turned on? or when the engine truns over? also on starting does the engine backfire before roaring to life?

 

[Spencer1]

doesn't sound like a bad battery, sounds like poor grounds... or poor connection on the starter solenoid. I have also seen dirty ignition switches and starter buttons cause hard starts and no starts with out a super charged battery.

does your headlight come on when the keyis turned on? or when the engine truns over? also on starting does the engine backfire before roaring to life?

X2 on the poor ground but there is possibly a different problem.

If the bike starts back up easily after only sitting a few minutes but if the bike sits more than a few hours and then you discover that it will not start I would suspect a bad wire somewhere causing a short draining your battery. Either way it's would not be your battery. It's possible you've got a bad battery but at this point (starts well after charging) I'd consider other things. If in doubt rip that battery out and take it to AutoZone or some other car part place for testing.

Since your headlight works well your stator is good which is the good news in all of this.

 

[crzychrs]

yes it does backfire sometimes when starting, and the head light does not come on with the initial turn off the key but after turning the motor over it does come on. the headlights shuts off when the starter is engaged. I will get that voltmeter and check and clean all of the grounds. thanks all

 

[Spencer1]

The headlight is suppose to shut off when the starter is running to send more juice to the starter.

 

[slimvulcanrider]

like fool and I said, its got to be a ground or wire symptoms... Mine used to do the exact same thing found the battery box to engine ground was corroded and loose. When I charged my battery there was enough voltage to bridge the loos connection for a few starts before I had to recharge the battery.

 

[crzychrs]

es it does backfire sometimes when starting, and the head light does not come on with the initial turn off the key but after turning the motor over it does come on. the headlights shuts off when the starter is engaged. I will get that voltmeter and check and clean all of the grounds. thanks all

 

[OleDirtyDoc]

The backfiring on starting sounds battery related.do you gave an agm battery?

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[riche]

The backfiring on starting sounds battery related.do you gave an agm battery?

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Yesterday when starting mine I got a couple of big backfires when trying to start it. It had been sitting for a few days, full choke, about 20F outside. Crank, crank -- boom! Crank, crank -- boom! Crank - start! Something else to worry about?

 

[WilliamTech]

Yesterday when starting mine I got a couple of big backfires when trying to start it. It had been sitting for a few days, full choke, about 20F outside. Crank, crank -- boom! Crank, crank -- boom! Crank - start! Something else to worry about?

fyi: If you start it everyday would possibly indicated you (possibly) have a battery issue, ( weak/non AGM battery). A weak battery (after 30 + seconds of cranking) can/will cause back firing with our 750 bikes. Expected ! .... AGM batteries MUCH less so.

time will tell..... if problem goes away.....

:smiley_th

 

[OleDirtyDoc]

A good charged acid filled one(non agm) will backfire with these bikes

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[WilliamTech]

A good charged acid filled one(non agm) will backfire with these bikes

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....there you go....

:smiley_th

 

[wmsonta]

These bikes are only like 5* advanced at idle. On a twin, if there is not enough battery to push though compression, it will backfire.

Though I did not understand before, AGM batteries are the thing.

 

[riche]

These bikes are only like 5* advanced at idle. On a twin, if there is not enough battery to push though compression, it will backfire.

Though I did not understand before, AGM batteries are the thing.

I will try out an AGM in it. My CB750K uses the same size battery. I'll borrow the AGM out of that and see how it goes.