Topic: OK heres my first post here. lets see how smart you guys are.

[mojomoto]

I bought a 78 cb750 a few years back for $100 bucks at a garage sale. Between other projects it is finally 85 percent or better ready. It has a cb750f tank, tach only, clubmans, guliari seat (chopped one at that!) Ill get a pic up if soon.
I got rid of the starter and would like to run batteryless.
OK here are the RULES.
If you dont think its possible or want to discourage me. DONT reply.
If you have any knowledge or experience, good ideas please reply.
The reason i know it will work is because of common sense. Apparently the alternator makes enough electricity to charge a battery and run a bunch of lights. Why wouldnt it work with just one headlight and a led tail? Especially if you can switch them off while kicking and have a capacitor. Or is there an alternator that would fit from something that makes more juice? Would an electronic ignition use more or less electricity? Do 750 spark at every rotation or just when it needs spark?
No battery works for cb350s ,360s, and 450s with a capacitor. I know because ive done it.
Good luck.

[Markcb750]

 

[my78k]

Wow....2 posts and you set the ground rules??? Well atleast you don't have any confidence issues  

Will it work??? Sure but you're gonna need a heck of a capacitor. Prolly heavier than any battery you're gonna run. Unless of course you plan on setting the idle above 3000 rpm since they run a deficit until around that range.

Wanna drop the weight of the battery?? Stop "supersizing" the fast food lol...

Dennis

Technically I didn't tell you it couldn't  be done!

[HavocTurbo]

Wow.... nice first post. Here's my question, but I don't want to hear all answers and opinions.

At least you know what you want right?

I believe our charging/ignition system is a 2 or 3 phase system. (I cannot remember which) Neither of which can be run WITHOUT a battery. Kick all you want.... it ain't happenin. At least not without major component replacement.

Here's an idea...

Call CycleX. www.cyclexchange.net I believe and get their batteryless ignition replacement system.

For $449.99 it'll be well worth replacing the time and energy spent here looking for things from members with all kinds of rules and stipulaitons.


I'm sorry I'm being and A$$. Having a bad day.

[HavocTurbo]

Wow....2 posts and you set the ground rules??? Well atleast you don't have any confidence issues  

Will it work??? Sure but you're gonna need a heck of a capacitor. Prolly heavier than any battery you're gonna run. Unless of course you plan on setting the idle above 3000 rpm since they run a deficit until around that range.

Wanna drop the weight of the battery?? Stop "supersizing" the fast food lol...

Dennis

Technically I didn't tell you it couldn't  be done!

Oh wtf Dennis!!! You beat me to it!!!! 

[upperlake04]

 

[Bodi]

Nuts to your rules.
When you reject the answer that comes from knowledge and experience, you tend to get input from the ignorant and unfamiliar.
***It won't work.***
The alternator does, of course, make enough power to run the bike. The problem is that the design used takes power to make power. The electricity is generated by placing a wire - the stator coils - in a varying magnetic field. If there were permanent magnets in the rotor, no problem. There are no such magnets. The magnetic field is solely produced by the field coil, by electrical current through the field coil wire. No electrical input to the field coil = no magnetic field. No magnetic field = no electrical output.
The alternator makes less power than is used by the ignition and the field coil below about 2000 rpm. The battery is required to provide this power at idle.
There are plenty of alternate generators and alternators that would work. You just have to fit one somewhere. You could add permanent magnets to the rotor I suppose.
A small gel cell is a whole lot easier.

[mystic_1]

If there were permanent magnets in the rotor, no problem. There are no such magnets. The magnetic field is solely produced by the field coil, by electrical current through the field coil wire. No electrical input to the field coil = no magnetic field. No magnetic field = no electrical output.

+1

mystic_1

[mojomoto]

Three phase will work without a battery. Ive got a three phase permanent magnet alternator from a honda shadow on my xs650. No battery. Works fine. A two pahse would work if i didnt want lights.
Would an electric igniton use less power?

Talk about quick response. Ill give you guys that much. just that though. Rules....ahem.

[MCRider]

To elaborate on what Bodi has said:  The CB750 differs from the rest of the bikes you listed in that it is the ONLY one that has an alternator with an "externally excited field". That is it must have current going in before current can come out. So batteryless with the current system is not possible. But I'm not saying it cannot be done. Sure it can be done. The CycleX product is the only one I've seen in nearly 40 years in production. There are some racer only systems but they won't drive lights, etc.

And for those 40 years I've heard constant rumors about someone modifying a CB350 or such to work, but have never seen one and whoever has done it is keeping a pretty good secret about it.

[hcritz]

Hey Mojo.
Just a few things I know...
I had a Triumph Bonneville that came with no battery...it had two large capacitors under the seat where the batter would normally reside. You turned the ignition off and kicked it through several times to charge the caps...then quickly switch the igniton on and kick it to start. Worked most of the time...If it didn't crank...you started all over.
NOW...the triumph system has a permanent magnet rotor...so anytime it rotated inside the stator it made some juice...
The Honda, on the other hand, does not...it uses a electrically excited rotor (electromagnet.. like and automobile alternator), So kick as hard as you like...unless there is just some residual magnitism built up in the rotor...it's not going to make any eletricity to charge the caps.  Not to say that there is not a way to accomplish running with no battery...it's just not going to be simple.

[HavocTurbo]

Three phase will work without a battery. Ive got a three phase permanent magnet alternator from a honda shadow on my xs650. No battery. Works fine. A two pahse would work if i didnt want lights.
Would an electric igniton use less power?

Talk about quick response. Ill give you guys that much. just that though. Rules....ahem.

You didnt listen.... CB750 does NOT have a permanent magnet rotor. Without changing things you will NOT get it to fire.

I'd go for the Cycle X parts. Ken prolly needs the business in this crappy economy. Plus that's a proven system on the 750.

[Spanner 1]

I know the answer, but I DON'T reply to SMART_ARSES....who already know the answer to the question ( it's obvious, dude ) before they post it, good luck !!

[HavocTurbo]

I know the answer, but I DON'T reply to SMART_ARSES....who already know the answer to the question ( it's obvious, dude ) before they post it, good luck !!

LOL I just like how it went from 3 replies to 12 in a matter of 30 seconds.... 

[mojomoto]

Well...there that makes sense. Thanks for your knowledge .Its an electro magnet thing like on my xs (kinda) not like a cb 350 or 450. is there a rotor with magnets out there that would fit inside the armature? (is that right?)  

[sangyo soichiro]

Gee...
If I ever need a quick answer, I'll just challenge your intellect in the thread title.   

Worked wonders for this thread!

[HavocTurbo]

Well...there that makes sense. Thanks for your knowledge .Its an electro magnet thing like on my xs (kinda) not like a cb 350 or 450. is there a rotor with magnets out there that would fit inside the armature? (is that right?)  

Ahem.....


www.cyclexchange.net

[my78k]

Did you forget about that thread you started about the plane taking off?? That got a few responses if I remember correctly!

[sangyo soichiro]

Did you forget about that thread you started about the plane taking off?? That got a few responses if I remember correctly!

I've got a few more cute little physics-type riddles, but I'm too afraid to post them now.      

[MCRider]

Did you forget about that thread you started about the plane taking off?? That got a few responses if I remember correctly!

I've got a few more cute little physics-type riddles, but I'm too afraid to post them now.      

be afwaid, vewy, vewy, afwaid.   

[Markcb750]

Fear not Soichiro.

We will participate no matter how much you obfuscate.  

[sangyo soichiro]

Hardy har har.      

[mystic_1]

Two phase, three phase, twelve phase, it matters not after it passes through the rectifier.

I know that some bikes use one phase for lights and the others for ignition, no Honda that I've worked on does this.

mystic_1

[Derby City]

My bike runs on water.  Send me $100 and I'll tell you how it works.

[Sporkfly]

Smart enough to use the search function! 

http://forums.sohc4.net/index.php?topic=10695.0

I would very much like to see the bat pac pointer in the FAQ removed, as I don't see how it can work with the SOHC4 charging system that needs the field excited to produce any power, ever.  To my knowledge not one single person has EVER posted a working solution using this device.
I'm very close to my limit of rehashing this same old topic.  I fear the value of this forum will be severely diminished if we continue with a policy of distributed misinformation.

Sean,
My recommendation is that you work up an electrical budget for the bike you wish to build, using the components you plan on incorporating.
Here's a spring board example:

Stock CB 750 electrical budget   /  minimum lighting
3.3 A  / 40 W -low beam Headlight
___________- Neutral lamp
___________- oil lamp
0.58A / 7W    -tail light
1.91A / 23W  -Stop light
1.17A / 14 W  -7W   x 2 Front run lights
1.0 A  / 12W   - 3W X 4 Instrument lights
1.2 A  / 15W  - ignition estimate  (while idling with points, 95 degree dwell on each, 5 ohm coils)
1.7A   / 20.4W – Alternator field coil (While idling)
0.0A   / 0 W - Turn sigs?
__________ - Dyna ignition module ?
9.78A  /117.4W -total  (normally drawn from system)
 0.05A /2.5W  - wiring, connector, and switch contact resistance losses
                       (Assumes 0.5 v voltage loss in wiring at 10 A draw)

approx.  3.28A (or 40 watt) delivery from alternator at idle (1000RPM), provided field coil is powered with 12V.
Extrapolated from Honda Shop manual chart of 6.5 amp drain with lights on.

Peak Alternator output – 17.5A  (210 watts at 5000 RPM)

To run the engine, the ignition and alternator must be fully powered (1.7 + 1.2 A or 2.9 Amps) The idling alternator (without battery) can probably supply this much power.  Just don't step on the brake or operate ANY lighting.  You'll still need a power source (about 3 amps) to get the alternator and bike started with ALL lighting disabled.

Warning...There may be math errors above.

Cheers,