1967 CB450K0 Black Bomber Rebuild - By Royhall

[royhall]

Hope that wasn't the actual one you were going to fit Ash. If it was, sorry I just nicked it. How does that wire into the Bomber harness? Can it be done from the rectifier cables to prevent cutting the harness. Looks like I would have to cut the red in after the fuse, the yellow could join next to the rectifier, and the black to any black. Is that correct?

Here's the wiring diagram for the later models with regulator (again courtesy of the Clymer manual, copyright and all that).

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[MrDavo]

My CL450 seems to have trouble getting over 12v when it should be charging, so what you say about 50 year old magnets losing there mojo is interesting to me. I wonder how feasible it is for me to make it so all the coils charge all the time.

That said, it must just about hold its own, I’ve not had a flat battery or come home with yellow lights. Most bikes when you rev them with the headlight on you see it get brighter but not this one.

[AshimotoK0]

No worries Roy .. I have enough of them for my bikes that will use them.

If you trawl through this download link below (in Dropbox links on here)  ... some interesting stuff ... it discusses low output alternators that were fitted to overcome damaging batteries and then the introduction of the solid state regulator in 1968 to cure this. Also these shots i just did from the CB250k manual will help explain things. I will check the wire colours for you.

General Collection of Honda Service Bulletins for various American Honda models. (many thanks Isaias from Facebook for these  .

https://www.dropbox.com/s/2frhyulrq2wyo7o/Bulletins%201-129%20%28incomplete%29.pdf?dl=0

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[MrDavo]

Ash do you think my 69 bike, which has the same rectifier and regulator as shown in that bulletin, is just working as intended by not frying the battery?

If so, I’ll leave the charging system alone.

[AshimotoK0]

Ash do you think my 69 bike, which has the same rectifier and regulator as shown in that bulletin, is just working as intended by not frying the battery?

If so, I’ll leave the charging system alone.

Best thing to do is connect an ammeter in series with the battery (or use clamp on DC ammeter) but DON'T operate the electric start and take some current measurements at various RPM's with and without the lights switched on.  You can then make an assesment to see if the alternator rotor magnets are weak. I assume a '69 CL 450 model has the SS regulator fitted? The SS regulator doesn't cut in until well above 12v  .. it cuts in when the battery is sensed as being  charged to almost full capacity

EDIT: cuts in between 14 and <15v

[AshimotoK0]

Here you go lads from that download but only screenshots ...sorry !  ... Much clearer in the full Adobe pdf doc. Tons of other useful stuff on the 450 in that download too.

The 'rubber cap' they refer to is only on the very early versions of the regulator box (I have that type on my really early CB250K0's with the hydraulic cam chain tensioner). I think it insulates the stud of the thyristor that's used as a voltage clamp..probaby replaced by a non-stud type (plastic body) in later versions of the regulator.  A thyristor is often referred to as an 'SCR' .. Silicon Controlled Rectifier ... it's what was also used in early Kawasaki etc. CDI's to discharge the HV capacitor into the ignition coil primaries.

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[AshimotoK0]

One thing I am not sure about is if you permanently connect the nightime coil, whether the regulator can handle the excess power generated when riding without the main headlamp switched on. One of these days I going to de-pot one of those regulators and see how it ticks....although it woud be fairly easy to just design a new one with a much higher current duty thyristor. Thyristors were the new kid on the block in the 60's and hence were probably very expensive back then.

This one is rated at 32A and relatively inexpensive (probably cheaper on eBay but you coud gurantee the quality on this one).

https://uk.farnell.com/stmicroelectronics/btw69-800rg/thyristor-50a-800v-top3/dp/1057302

[Bryanj]

I got an account with Farnell if you decide you need one(or two)

[AshimotoK0]

I got an account with Farnell if you decide you need one(or two)

Thanks Bryan but I have had trade account for about 25 years with Farnell RS and Rapid  and ordered parts this week from Farnell for a work job. TBH I probably already have a few beefy thyristors to try ... just don't want to reinvent the wheel though. There is already stuff out there but not researched yet. Like this DIY one.  https://mastercircuits.blogspot.com/2010/11/single-phase-voltage-regulator.html

[nigelrharris]

If I could put my twopence worth in. I have had a Bomber since 1971. The same one to be fair we have been through a lot including poor charging. I have now a charging system that is good enough to require a voltage regulator. I was getting up to 16 VDC which was too much for the AGM battery, its now at a constant 14v. 
The basic system is a magnet that spins in a coil. The magnet had the starter clutch on it which could well have been a source of your issue. 

The original coil may have had insulation leakages. It has three pairs of coils two are for Night time running and come in when you turn on the headlamp and one for day. I never ride without light these days.
I had the coils professionally rewound at a place in Sussex. Not the originals but the work better. I purchased the last NOS rotor from Silvers. Yes it was painful but worth it. I believe that you can get these magnetised too.   

I have a new diode rectifier with significantly less internal resistance from RS it works a treat and is fitted to a heat sink along with the voltage regulator.
The biggest problem I had was the starter clutch had come lose in the past. It sounded like a run big end to be honest it was that bad. This had vibrates and partially demagnetised the rotor. Hence the change of Rotor. Cheap silicon rectifiers work well. I have a 20A fitted to an aluminium heat sink in the rectifier well this also takes the VR.
 

[royhall]

Does anyone have a clear photo of a Bomber with the tank and seat off. I am just trying to put the new harness in place and have conflicting instructions across all three manuals. Three manuals and three different routes, who would have thought. It's usually Haynes that's the odd one out. One good clear photo and it's job done.

Thanks for posting the manuals and bulletins Ash. I had already seen the bulletin about the low power early alternators when I was building the engine. As I have used a much later alternator that is what prompted the thinking I need a regulator of some sort.

[AshimotoK0]

Can't really help you there Roy. There are some high res pics of Mick's 2.5k mile unmolested one  he sold but non with the tank off. I can ask of FB for you though if you wish.

https://www.dropbox.com/sh/4u9p8tzi6c6sbld/AAApj8jf5aTlziAZbcil6_gXa?dl=0

[royhall]

That would be great. Thanks Ash.

[AshimotoK0]

That would be great. Thanks Ash.

Done .. I will post on here if I get a response. Will need that information myself soon.

[AshimotoK0]

That would be great. Thanks Ash.

Done .. I will post on here if I get a response. Will need that information myself soon.

I got this back from FB Roy but not sure how unmolested it is though. 

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