Topic: Won't kick start with weak battery, true?

[ct_bobber]

my battery is already weak.  I could not get it out running around to charge it properly yet. Today, I could start it with a kickstart.  It started up fine.  Then, I went running around town and forgot to turn the key off.  When I came back the indicator lights are still lid, but the brake light was barely illuminated.  Now, the bike won't start at all no matter how many time I kicked.

So, my question is, can the bike start using a kickstart even when the battery is almost dead?  Or does the battery need to have some juice in order to kickstart?  I searched and got two different answer, one said battery needs a little juice to start the bike with kickstart, another one said it should not matter b/c that's what kickstart is for.  I'm not quite sure and would love to hear from some experts on this site to confirm this.  By the way, my bike is '75 CB750.

Thank you very much.

[bartsitarski]

You should be able to kick start. I regularly run my battery down to the point that it wont crank the motor due to city stop and go. I know that this is not good for the battery, but, not much I can do. Once I have a garage, i will do a battery tender. Till then, kick start from time to time when the battery is barely powering lights.

[Medyo Bastos]

i have not charged my battery in 6yrs, and have not had to kick it over yet! 

[MCRider]

You should be able to kick start. I regularly run my battery down to the point that it wont crank the motor due to city stop and go. I know that this is not good for the battery, but, not much I can do. Once I have a garage, i will do a battery tender. Till then, kick start from time to time when the battery is barely powering lights.

Sorry. What bike?  ^^^

The CB750 will not kickstart with a flat battery. It is one of the very few if only models that has an "externally excited fieldl" type alternator. Which means it must have power going in to put out power...to start.

Not true for any other CB/4, just the 750.

[ct_bobber]

thank you for your response.  I'll try to charge battery tomorrow and see if it makes any difference.

this post also says that our bike doesn't have magneto, so the battery still needs to have some voltage in order to kickstart.

http://forums.sohc4.net/index.php?topic=121125.0

We'll know tomorrow.  I hope it's just battery.

[MCRider]

thank you for your response.  I'll try to charge battery tomorrow and see if it makes any difference.

this post also says that our bike doesn't have magneto, so the battery still needs to have some voltage in order to kickstart.

http://forums.sohc4.net/index.php?topic=121125.0

We'll know tomorrow.  I hope it's just battery.

A magneto is probably not the correct term but they are referring to a more conventional system which will generatte power to the coils all on its own. The CB750 simply can't do this by design. It is a proportional thing. The weaker the bat is the harder it is to kickstart. Till you get to a point there is not enough current in the bat to charge the field coil to make the rest of the alternator work.

[MCRider]

I'm pretty sure this does not apply to CB550s, 400s, etc. IF you got the leg, it will start.

However, all of our bikes are old and succumb to losses from dirty corroded connections etc, even with a fresh battery. Studies have been done where overhauling all the connections, cleaning and greasing them, can add 1-2v to the system.

[ct_bobber]

Thank you very much for the information.  I'm feeling a bit better now.

MCRider, since I have you here , I hope you don't mind pointing me to the right place for my next task.

It looks like my cylinder #1 not firing (exhaust cold).  Once I get the bike to start, I will troubleshoot this.  Could you point me to steps I should take to troubleshoot this?  this is what I plan to do, but if it's not correct, please let me know.

• I will start with the plug and check if it gets power.
• Then, I know I should check if Cylinder #1 gets fuel, but i don't know how to check this?

[li]Anything else I should check after spark and fuel?
[/li][/list]   

thank you in advance.

[MCRider]

Thank you very much for the information.  I'm feeling a bit better now.

MCRider, since I have you here , I hope you don't mind pointing me to the right place for my next task.

It looks like my cylinder #1 not firing (exhaust cold).  Once I get the bike to start, I will troubleshoot this.  Could you point me to steps I should take to troubleshoot this?  this is what I plan to do, but if it's not correct, please let me know.

• I will start with the plug and check if it gets power.
• Then, I know I should check if Cylinder #1 gets fuel, but i don't know how to check this?

[li]Anything else I should check after spark and fuel?
[/li][/list]   

thank you in advance.

1 & 4 are fired off the same coil and points. So 4 would be dead too, if its coil or points. Plugs and plug wire are distinct to each cylinder.
If you haven't had the bike long and its always run like this, I anticipate carbs. Need a good cleaning. Not my specialty, but others here are very good with them.

[Medyo Bastos]

also try trimming 1/4" off the #1 plug wire and reattaching the plug cap securely

[MCRider]

also try trimming 1/4" off the #1 plug wire and reattaching the plug cap securely

That's a good idea!

The plug cap threads into the wire. Just screw it off/out. Cut and square off the wire, thread the cap back on.

[ct_bobber]

 Thanks I will try that.  Just a curiosity, how would that help?

[zenocchio]

The 500 too will not kickstart with a weak battery

[MCRider]

Thanks I will try that.  Just a curiosity, how would that help?

Corrosion of the wire at the point where the plug cap screws into it, causes a weak spark. It may still spark, just very weak. When you snip the wire you're getting rid of the corroded part and getting back to some clean wire.

On these older bikes you have to be suspicious of all wire/plug connections. Corrosion is everywhere.

[TwoTired]

I still don't know what bike you have.  But, all the SOHC4s need voltage to power the coils and get spark.  Since the alternator does not have a permanent magnet, the electromagnet it does have needs battery voltage (as well as power for the coils) to start the bike.  A flat battery cannot supply enough power to both, and little to no power is generated by the alternator at such a low RPM as kick start speed.

Jump start from a good battery, or recharge the one you have.


FYI, it will take 10 hour of 5000 RPM operation to recharge am expended battery.  They charge little if any at idle, and even less so with the lighting on.

[MCRider]

The 500 too will not kickstart with a weak battery

My understanding is ... it should. It's not the design of the alternator keeping it from starting, as it is on the CB750.  In your case, you have to be suspicious or all your connections, bike-wide, as keeping you from being able to start easily with a low battery.

[MCRider]

I still don't know what bike you have.  But, all the SOHC4s need voltage to power the coils and get spark.  Since the alternator does not have a permanent magnet, the electromagnet it does have needs battery voltage (as well as power for the coils) to start the bike.  A flat battery cannot supply enough power to both, and little to no power is generated by the alternator at such a low RPM as kick start speed.

Jump start from a good battery, or recharge the one you have.


FYI, it will take 10 hour of 5000 RPM operation to recharge am expended battery.  They charge little if any at idle, and even less so with the lighting on.

His post says its a 75 CB750.

Am I wrong in sayiing that the CB750 is alone in the externally excited field? I thought the 500/550s and others were not that way. OCICBW

[ct_bobber]

Ok, I will report back what I find.  My bike is 1975 CB750.  This would be my first (big) bike.  I used to ride 250 Rebel and still ride 2 stroke Bajaj Chetak (Vespa look).

This is the one I'm working on.



I'll be riding this until CB750 is running correctly - 1980 Bajaj Chetak (150cc 2-stroke)




This was my first bike - 1999 Honda Rebel.

[Medyo Bastos]

Thanks I will try that.  Just a curiosity, how would that help?

Corrosion of the wire at the point where the plug cap screws into it, causes a weak spark. It may still spark, just very weak. When you snip the wire you're getting rid of the corroded part and getting back to some clean wire.

On these older bikes you have to be suspicious of all wire/plug connections. Corrosion is everywhere.

the other thing to keep in mind is that the plug caps screw on allowing them to wiggle themselves loose over time.

[zenocchio]

The 500 too will not kickstart with a weak battery

My understanding is ... it should. It's not the design of the alternator keeping it from starting, as it is on the CB750.  In your case, you have to be suspicious or all your connections, bike-wide, as keeping you from being able to start easily with a low battery.

interesting.
Last year i got stranded because I was running with my headlight on and a bad fuel coil that did not charged the battery.

the bike, while running, was not able to keep up and eventually died.
And I spent the rest of my day pushing it, until I swap out the dead battery for a fully charged one and it started at the first hit.

[MCRider]

The 500 too will not kickstart with a weak battery

My understanding is ... it should. It's not the design of the alternator keeping it from starting, as it is on the CB750.  In your case, you have to be suspicious or all your connections, bike-wide, as keeping you from being able to start easily with a low battery.

interesting.
Last year i got stranded because I was running with my headlight on and a bad fuel coil that did not charged the battery.

the bike, while running, was not able to keep up and eventually died.
And I spent the rest of my day pushing it, until I swap out the dead battery for a fully charged one and it started at the first hit.

Oh yeah, didn't I say...

OCICBW?   

[754]

My 74 750 had a battery with two frosty cells.
 Often when starting it, the idiot lights on handle bar clamps were very dim, battery was that low.. But it always started,  and that was winter weather.
 One time I started it rode two miles, then checked battery voltage..and it had charged up to 7 volts.
 So I can honestly say that with barely lit neutral. And oil light, it will still starts..and I haveDone it more than 50 times.
And I will say, that because it had some voltage, it actually is increasing as you kick it. Might take around 20 kicks..bump start on hill would do it..but if you have. Electronic ignition instead of points.. It won't start in those conditions..

[edwardmorris]

I'll be riding this until CB750 is running correctly - 1980 Bajaj Chetak (150cc 2-stroke)

Whoa! Last I saw a Bajaj Chetak was when I visited India a few years ago. Are you in/from India or do you have a Chetak here?

[ct_bobber]

  not from/in India.  I bought the bike here in the U.S.  I was looking for a vespa, but it was too expensive, so I found this with much cheaper price.  i have been riding it for 2 years now.

[TwoTired]

Am I wrong in sayiing that the CB750 is alone in the externally excited field?

Sorry.  I'm afraid so.

Cb350F, Cb400F Cb500, Cb550, and cb750 all have electrically powered field coils and steel rotors which create a rotating electromagnetic field for the stator windings.
The Cb650 only differs in that the rotor steel also contains windings, fed power via slip rings/brushes.

None of these alternators can produce power without an electromagnetic field, which is initiated with battery power.  Once the alternator RPM rises for it to overcome and exceed the electrical loads, it will self sustain until the RPM and thus output drops below the bike's standard system loading.  The battery acts as a reservoir during idle speeds to supplant the differential during idle, until the battery depletes to a point where the ignition coils cease producing spark.

Some report lower battery voltage operation than others.  But, the design goals are about 9V minimum.

[dave500]

the points ignition will run down to lower voltages than the electronic types,some die at 8/9 or 10 volts?points might still fire up at 4/5/6volts?

[Wobbly]

Coming back from a long North African/Sahara trip, my battery was dead. Most chambers did not have any acid left at all. Before the trip, I had checked the battery and all were at max level. Anyhow, even in this poor condition, the bike would always start on the first kick and I made it home just fine.

[MCRider]

Coming back from a long North African/Sahara trip, my battery was dead. Most chambers did not have any acid left at all. Before the trip, I had checked the battery and all were at max level. Anyhow, even in this poor condition, the bike would always start on the first kick and I made it home just fine.

What model bike?

[MCRider]

Am I wrong in sayiing that the CB750 is alone in the externally excited field?

Sorry.  I'm afraid so.

Cb350F, Cb400F Cb500, Cb550, and cb750 all have electrically powered field coils and steel rotors which create a rotating electromagnetic field for the stator windings.
The Cb650 only differs in that the rotor steel also contains windings, fed power via slip rings/brushes.

None of these alternators can produce power without an electromagnetic field, which is initiated with battery power.  Once the alternator RPM rises for it to overcome and exceed the electrical loads, it will self sustain until the RPM and thus output drops below the bike's standard system loading.  The battery acts as a reservoir during idle speeds to supplant the differential during idle, until the battery depletes to a point where the ignition coils cease producing spark.

Some report lower battery voltage operation than others.  But, the design goals are about 9V minimum.

Thanks for setting me straight. A trip to the fishies does indeed show the field coil for the CB500. I'll accept the rest are the same. I must have been thinking of the twins?

[Wobbly]

Coming back from a long North African/Sahara trip, my battery was dead. Most chambers did not have any acid left at all. Before the trip, I had checked the battery and all were at max level. Anyhow, even in this poor condition, the bike would always start on the first kick and I made it home just fine.

What model bike?

My 77 K7.

[MCRider]

Coming back from a long North African/Sahara trip, my battery was dead. Most chambers did not have any acid left at all. Before the trip, I had checked the battery and all were at max level. Anyhow, even in this poor condition, the bike would always start on the first kick and I made it home just fine.

What model bike?

My 77 K7.

Interesting. Your experience is what it is. But I think you were lucky.   

[ofreen]

the points ignition will run down to lower voltages than the electronic types,some die at 8/9 or 10 volts?points might still fire up at 4/5/6volts?

I know my 750 with the Dyna S will fire at 8 volts.  The headlight has to be disconnected for it to start.

[Wobbly]

Interesting. Your experience is what it is. But I think you were lucky.   

I was lucky indeed. This was 1983. I would not recommend trips through the Algerian Sahara today--unless there's a Marine Corps Battalion behind you.
The battery was so dead that you could barely see the neutral/oil light when the ignition was turned on--with the final 500 miles still in front of me. As a side note: the Honda did great otherwise during the trip, despite the heat (July/August) and being terribly overloaded, and carrying my wife as a passenger. I got sick as a dog though, stuck in a place where there was only one hour of running water during the day.

[ct_bobber]

Thanks all for the replies.  The battery and kickstart issue is solved.  It fired right up as soon as I jump it.  Now I have to figure out the Cylinder #1 not firing.  I started a new post so it would be easy to track http://forums.sohc4.net/index.php?topic=134497.0

Thank you very much.

[lucky]

i have not charged my battery in 6yrs, and have not had to kick it over yet!

That duel disc brake on that extended and raked bike in your avatar can get you killed.
Be very careful Medyo Bastos.

That is why you do not see duel discs on long choppers.
The duel discs can lock up the wheel and just snap or bend the front forks.