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Discussion Starter #1
Greetings.
I recently picked up a 74 CB350. As many of you know, the charging system on these are woefully inadequate. Since I suck at all things electrical, I'm looking for any tips and/or fixes for this system. I've got a new battery installed. I use the kick start exclusively. I invested in a battery tender and plug it in often. I even throw the law and my safety out the window and drive during the day with my headlight off. Most of my driving is within the city (Chicago) so I rarely am able to get enough RPM's to adequately charge the battery (at what point does it charge by the way? 3000 RPM?)
I would prefer to find a permanant fix for this problem. Is it possible? I mean, if my '65 Lambretta can function without a battery at all, surely I can get this bike roadworthy.
Any advice would be greatly appreciated. Thanks.

1974 CB350F
1965 Lambretta Li150
2003 Stella
 

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I wouldn't say 'woefully' just inadequate. Never intended to be driven with the lights on all the time.

You are on the right track. If you do the things listed you should be good to go. Check your tach, it goes to 9000. Get the revs near up there now and again to charge her up. If it still isn't enough check the rectifier and regulator.

Or just tear the electrical system out of your scooter.

BORN TO LURK, FORCED TO WORK.
www.NYCvinMoto.com
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Johnny,
Since you ave the 350f 4 cylinder, It can not run without a battery. It uses a battery excited alternator so the magnets are electro magnets, not permanent. If you are doing all the things you say then you should be fine if the charging system is working up to par. I had a 400f for years and had absolutely no problems and my sister had the same year 400f and had to put a headlight switch in it and charge her battery periodically. When I used her bike I never had any issues with it. Difference being, I like redline. A lot!! Those little bikes need to be ridden hard. Even in the city. You will enjoy the bike more the harder you rev it. One other thing to check is the white rectangular connector from the regulator rectifier unit. They can corrode and overheat. Pull it apart and check for green corrosion or signs of overheating( the plastic will turn brownish).
If al the parts are working as designed, you should be fine using the electric start and everything if you ride it hrd.

Ride it is like my sisters.

Ken

AHRMA 412
Vintage racing - old guys on old bikes
 

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Let's work out if the problem is with the charging system or how you ride. Take a voltmeter reading across the battery terminals with the bike off, then at idle (1.2-1.5k or so), 3k, 5k and 7k. You should be in the neighborhood of 12.5v with the bike off, low 12s or a little below at idle, mid-12s at 3k, high 12s to 13 at 5k, and somewhere over 13 at 7k. If your battery's much lower than 12.5 when your bike's off I'd call your battery suspect (or at least in need of a charge) - if it reads lower than the above at revs than I'd check the connections, voltage regulator, etc. I can send you a diagram for a better voltage regulator that you can build for a few bucks in radio shack parts and ten minutes of soldering if you need.

A
 

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i had issues with battery drain on my cl350. i fixed it by replacing my rectifier with a five dollar piece from radioshack and the connector from my old one. somewhere i have a diagram and some photos archived, i'll dig them up and post them later today.

...connoisseur of slack...
 

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Just to note, the CB350f uses an entirely different charging system than the cb350 or 450 twins. It uses a battery excited alternator and has a solid state regulator/rectifier unit.

But, Xander is right, You should take some baseline readings on your charging rates at various RPM.

Ken

AHRMA 412
Vintage racing - old guys on old bikes
 

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Discussion Starter #7
quote:
Johnny,
Since you ave the 350f 4 cylinder, It can not run without a battery.
Yeah, I found this out already a few days ago when the bike died halfway home from work.
Thanks for the good advice everyone!

1974 CB350F
1965 Lambretta Li150
2003 Stella
 

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good point ken, xander and i have the same rectifier info and i don't know if it's compatible with the 350f's. i do know that the replacement rectifier is solid state so it might be worth looking into.


the numbers on the part are BII72 BR356W
...connoisseur of slack...


Edited by - snorkelfork on Jul 04 2007 5:19:30 PM
 

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most honda break even charging is 2000 rpms. Just thought I would throw that out there.

I don't know if your voltage regulator is the adjustable kind or not but you used to be able to pop off the cap of them and adjust it with a screw driver.




Edited by - geeto67 on Jul 04 2007 5:56:06 PM
 

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Oops, meant 'rectifier', not 'voltage regulator' above... and, for the record, that "ten minutes of soldering" was done by snorkelfork 'cause he's just better at soldering than I am. There, I said it.

Ken... so the v/r and rectifier are integrated on the 350f? Funky. That was the first bike I ever rode, but it was my brother's and he killed it long before I ever got to see what was inside.

A
 

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so the 350f does have a different rectifier. the 350 twin model he sells is the exact same thing xander and i built our cb450 and cl350. but ours cost five bucks and 30 minutes.

...connoisseur of slack...
 

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Discussion Starter #15
quote:
so the 350f does have a different rectifier. the 350 twin model he sells is the exact same thing xander and i built our cb450 and cl350. but ours cost five bucks and 30 minutes.

...connoisseur of slack...
So the above mentioned rectifier from Oregon Motorcycle won't work my CB350F?

1974 CB350F
1965 Lambretta Li150
2003 Stella
 
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