VB21B pressed in idle jet orifice depth and other leaks and glitches

do we have any idea what the charging amp are to the battery? A standard silicone diode should have a voltage drop of about .6-.7 volts. it would have to be rated for enough amps though. I remember the old craftsman cordless drills used the same charger for the 12v and the 14.4 volt systems, they just used 2-3 diodes in series to drop the voltage.
 
esmith250624 said:
do we have any idea what the charging amp are to the battery? A standard silicone diode should have a voltage drop of about .6-.7 volts. it would have to be rated for enough amps though. I remember the old craftsman cordless drills used the same charger for the 12v and the 14.4 volt systems, they just used 2-3 diodes in series to drop the voltage.
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Don't know. FSM says 5 amp and 14.5 volt minimum, no maximums specified. I get lost in the weeds pretty fast on this stuff. My little voltage meter blinks over 15.6 and it's blinked a few times but mostly stays 15.3-15.4, which really is too high. New gel AGM battery shows 13-13.2 after resting, which is pretty abnormal compared to the other bikes here. Usually, these gels seem happy at 12. 7 or so for longevity. $100 for Sparcks mosfet ain't too bad. Gel AGM's are $50 so....
 
I don't know Tom. Are you positive the key switch is not causing a voltage drop over 0.9V? This will also affect things. Just throwing ideas out there because it's quite expensive to buy another voltage regulator brand new and it won't mount the same anyways.

If you're really bored you can search by the actual part number on the regulator. It's still used in modern bikes so you can find them cheap sometimes on eBay used.
 
Maraakate said:
I don't know Tom. Are you positive the key switch is not causing a voltage drop over 0.9V? This will also affect things. Just throwing ideas out there because it's quite expensive to buy another voltage regulator brand new and it won't mount the same anyways.

If you're really bored you can search by the actual part number on the regulator. It's still used in modern bikes so you can find them cheap sometimes on eBay used.
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Good point Frank. The Black sense wire tells the regulator the needed charge, if the voltage the regulator sees is low then it will allow more charge voltage thru. Bad contacts in the ignition switch or bad connections will reduce the voltage
 
LongDistanceRider said:
Good point Frank. The Black sense wire tells the regulator the needed charge, if the voltage the regulator sees is low then it will allow more charge voltage thru. Bad contacts in the ignition switch or bad connections will reduce the voltage
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I will test that (kill/key switch) with your test Jim.
 
Maraakate said:
I don't know Tom. Are you positive the key switch is not causing a voltage drop over 0.9V? This will also affect things. Just throwing ideas out there because it's quite expensive to buy another voltage regulator brand new and it won't mount the same anyways.

If you're really bored you can search by the actual part number on the regulator. It's still used in modern bikes so you can find them cheap sometimes on eBay used.
Click to expand...
Seems to be right around there, a < 1 volt drop. I have a Sparck moto unit, but think the old Shindigen one might still be ok too.
LongDistanceRider said:
Good point Frank. The Black sense wire tells the regulator the needed charge, if the voltage the regulator sees is low then it will allow more charge voltage thru. Bad contacts in the ignition switch or bad connections will reduce the voltage
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I cleaned all the connectors (in bucket and side cover) and backprobed all the switched power (black wire) spots I could. Everything done with the bike not running and the battery full at 12.8 volts. All power showed about 11.9 (not surprising with bike not running, battery only, headlight always on).

These regulators all get their clue downsteam from the switch and since it runs about a volt less, why not connect the sensing wire directly to the battery?

I noticed the mosfet types don't even have a sensing black wire but are also wired directly to the battery with the second connector and 10 gauge wire.
Seems mosfet get it's orders direct from headquarters (battery).

Final question for Jim: Will the mosfet fit under the side cover in a CB400T?

If I'm off base here by a mile, please say so. I know I'm not really qualified to ponder these things but tuition here is cheaper than the community college and I don't have to put up with attitude or pay ridiculous parking rates. :D
 
It's possible they could drift but they're simply diodes and those are usually pretty reliable. A final option would be to nip back all the terminals going to and from the reg/rec and crimp with new ones. Possible one is slightly corroded but you can't see it until you strip back the wire and see that it's green.
 
Maraakate said:
It's possible they could drift but they're simply diodes and those are usually pretty reliable. A final option would be to nip back all the terminals going to and from the reg/rec and crimp with new ones. Possible one is slightly corroded but you can't see it until you strip back the wire and see that it's green.
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Okay, I'll get a proper kit and do that.

What do you think of connecting the sensing wire to the battery itself?

EDIT: Duh. It wouldn't be switched! Maybe I'll go back and check the red from battery to key switch.
 
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This is good info.. I am going to look at mine too. What if you run a temporary wire between these two points, you would be eliminating 3 on the connections. I am also curious if you dug into the Regulator connection I circled in blue. is that buried in the harness? (what type of connector is it?) Did you determine if the voltage drop at one of these 4 connection points is more than the other? The 5th connection would be key switch. (Not in frame of this photo)

1717421603589.png
 
When it gets into wire mods it's beyond me I really do not know the answer to that. What I do know is that those reg/recs are basically very beefy diode bridge mounted to a large heatsink. If you really wanted to you could make one yourself. It's basically 4 diodes to rectify the AC from the alternator to DC: https://en.m.wikipedia.org/wiki/Diode_bridge
 
Check your battery input(Red wire) to the Ign switch and output on the Black wire, should match up.
I haven't installed the Mosfet unit on your model, fit fine on the CM version with some mounting hole mods.
Looking at a picture of the CB I think it'll fit fine
RIMG0648.JPG

Randy posted the dimensions here https://roadstercycle.com/Shindengen FH020AA mounting dimensions.htm
 
esmith250624 said:
This is good info.. I am going to look at mine too. What if you run a temporary wire between these two points, you would be eliminating 3 on the connections. I am also curious if you dug into the Regulator connection I circled in blue. is that buried in the harness? (what type of connector is it?) Did you determine if the voltage drop at one of these 4 connection points is more than the other? The 5th connection would be key switch. (Not in frame of this photo)
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If the deficiency is in the black wire (switched) then yes, it could help (I think) but I'd love to find and fix the deficiency first.

IOW, hold that thought.

I think Frank's right and Jim is pointing the way.
 
Maraakate said:
When it gets into wire mods it's beyond me I really do not know the answer to that. What I do know is that those reg/recs are basically very beefy diode bridge mounted to a large heatsink. If you really wanted to you could make one yourself. It's basically 4 diodes to rectify the AC from the alternator to DC: https://en.m.wikipedia.org/wiki/Diode_bridge
Click to expand...
Thanks Frank. Further, nothing really changed with either rec/reg unit.

I'm going back to your earlier advice and re- check the 2 pin plug (and red wire) on the right side at battery.
 
If you're real bored Tom get an old regulator from an SOHC4. They're worth nothing because the clowns at SOHC4 forums think it's junk because it's a separate unit and that the bikes don't charge at idle (news flash: they all don't!). It's entirely adjustable and serviceable. They're worth $5 and the rectifiers are also worth nothing. I know you like cheap and don't mind fabbing stuff. Might be up your alley...
 
LongDistanceRider said:
Check your battery input(Red wire) to the Ign switch and output on the Black wire, should match up.
I haven't installed the Mosfet unit on your model, fit fine on the CM version with some mounting hole mods.
Looking at a picture of the CB I think it'll fit fine


Randy posted the dimensions here https://roadstercycle.com/Shindengen FH020AA mounting dimensions.htm
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I bet you're over target, on the red and black. I think, because of the way these bikes are wired to power the switch, it's suffering right there. IOW, wimpy input to switch equals wimpy output to the regulator.
The Mosfet wiring would eliminate this weakness as well by coming right off the battery, instead of the connection made at the solenoid.

Good to know it probably fits.
 
Maraakate said:
If you're real bored Tom get an old regulator from an SOHC4. They're worth nothing because the clowns at SOHC4 forums think it's junk because it's a separate unit and that the bikes don't charge at idle (news flash: they all don't!). It's entirely adjustable and serviceable. They're worth $5 and the rectifiers are also worth nothing. I know you like cheap and don't mind fabbing stuff. Might be up your alley...
Click to expand...
But Frank, I'm just not in your league.

I got to learn "fix it" before thinking about "fab it". :D
 
The ignition switch isn't hard to get apart. Take a real close look at the canon plug going to it and on the switch itself. Possible one of the positive wires in it are corroded.

If you need the crimp connectors I literally have hundreds leftover from the CDIs because they're 6 pin but only 4 are used. Let me know if you need some thrown in an envelope. What ive done with my own personal bikes is extract every terminal connector one at a time and nip it back and crimp new connectors on. Literally every one. Then dielectric grease on female side and the back of the connectors to prevent this kind of bologna in the future. Takes a day or two, but worth it imo if you're daily driving.
 
And don't forget the fuse box. Another place big voltage drops occur. Check it in the back for signs of overheating and the canon plug. I've replaced or serviced quite a few for customers in the past.
 
I want to report what I found on mine, initial test battery 12.35 key switch on so running lights on, but headlight removed for testing. voltage at regulator connector (black wire 11.47v) so voltage drop of almost a volt. Key switch is getting about a 0.1v drop through it. mine is a replacement (keys were lost at some point) Inspected two wire red connector at battery, Terrible connection cut it and crimped on a new connector. then checked white ignition connector in headlight bucket. getting pretty good drop from that too, (from red input to black output when you turn the key) so removed and cleaned connectors. check for voltage drop at black connector, ok there, since it is just a piggyback splice there. Cleaned connector at Rectifier/regulator. Put everything back together. getting about a 0.4 - 0.5 voltage drop total now on black wire at the Regulator. So fired it up, meter on the battery. tested a few rpm ranges and anything above 1800 ish is steady at 14.72V

Thanks for starting this thread, I probably would have just left mine until the battery wire broke or the battery got fried.
 
esmith250624 said:
I want to report what I found on mine, initial test battery 12.35 key switch on so running lights on, but headlight removed for testing. voltage at regulator connector (black wire 11.47v) so voltage drop of almost a volt. Key switch is getting about a 0.1v drop through it. mine is a replacement (keys were lost at some point) Inspected two wire red connector at battery, Terrible connection cut it and crimped on a new connector. then checked white ignition connector in headlight bucket. getting pretty good drop from that too, (from red input to black output when you turn the key) so removed and cleaned connectors. check for voltage drop at black connector, ok there, since it is just a piggyback splice there. Cleaned connector at Rectifier/regulator. Put everything back together. getting about a 0.4 - 0.5 voltage drop total now on black wire at the Regulator. So fired it up, meter on the battery. tested a few rpm ranges and anything above 1800 ish is steady at 14.72V

Thanks for starting this thread, I probably would have just left mine until the battery wire broke or the battery got fried.
Click to expand...
Yes that 2 pin canon plug that goes from battery to reg/rec is overlooked in the 400 twins and almost every bike I see needs it fixed in both ends. My own included.
 
esmith250624 said:
I want to report what I found on mine, initial test battery 12.35 key switch on so running lights on, but headlight removed for testing. voltage at regulator connector (black wire 11.47v) so voltage drop of almost a volt. Key switch is getting about a 0.1v drop through it. mine is a replacement (keys were lost at some point) Inspected two wire red connector at battery, Terrible connection cut it and crimped on a new connector. then checked white ignition connector in headlight bucket. getting pretty good drop from that too, (from red input to black output when you turn the key) so removed and cleaned connectors. check for voltage drop at black connector, ok there, since it is just a piggyback splice there. Cleaned connector at Rectifier/regulator. Put everything back together. getting about a 0.4 - 0.5 voltage drop total now on black wire at the Regulator. So fired it up, meter on the battery. tested a few rpm ranges and anything above 1800 ish is steady at 14.72V

Thanks for starting this thread, I probably would have just left mine until the battery wire broke or the battery got fried.
Click to expand...
Thanks for the report, helps tighten my shot group or check my zero, in shooter speak. Got my work cut out now.
 
No smoking gun yet.
Cleaned right side 2 pin connector, no voltage drop till after the switch. Before cleaning the switch, there was about 30ohm resistance, now in lower single digits. I only sprayed the switch out through it's side hole with CRC electromechanical cleaner then with carb spray and even WD40 several times while working the switch and blowing with compressed air. Same with red wire from battery to bucket, only 1.5 ohm.

IMG_1372.jpeg
time to just test ride. At least a running charging test.

If it's still running at or near 15 volts, I just can't think of another way to induce the regulator to start restricting that. I'll give up and just put in a Mosfet that senses directly the battery voltage.


Sorry this thread has gotten so far from VB carb issues.
 
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I Understand. You can't chase it forever. I really want to know how that black wire in the regulator connector connects back to the harness. it is the one connection point that I could not put my eyes on. I have an old wiring harness that is already unraveling, so I am going to go look to see how that connects.
 
I have an actual copy of the FSM and not the PDF that's been floating around for 20 years on the web. I can get you a better quality picture of the wire harness. Let me know what year. I have all the addendums for the 400s.
 
And if you're unravelling the harness tape Mike has uploaded a PDF of an official Honda Service Bulletin with parts numbers for the connectors and the harness tape. The tape is quite cheap, about $3. If you have a local dealer nearby they can order it for you. It's better quality than the stuff Matt has at Vintage Connections: https://www.motorcycleproject.com/text/terminals_Honda_bulletin.pdf
 
Here is the location of that splice on my other harness.. This does not look like a factory solder splice to me, what do you guys think? on my spare harness this was just wrapped in electrical tape. Looks like this needed repair at some point. At least we know where to look.



1717505632605.png

1717505656904.png
 
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Maraakate said:
And if you're unravelling the harness tape Mike has uploaded a PDF of an official Honda Service Bulletin with parts numbers for the connectors and the harness tape. The tape is quite cheap, about $3. If you have a local dealer nearby they can order it for you. It's better quality than the stuff Matt has at Vintage Connections: https://www.motorcycleproject.com/text/terminals_Honda_bulletin.pdf
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Thanks, one of these days I might re-wrap that old harness and re-do the connectors.
 
That yellow tape on the other connector looks like rescue tape/self fusing silicone. I do not know about that solder splice on the black as I've never unravelled the harness on these before. I'll check the wiring diagram and see what it says.
 
Maraakate said:
That yellow tape on the other connector looks like rescue tape/self fusing silicone. I do not know about that solder splice on the black as I've never unravelled the harness on these before. I'll check the wiring diagram and see what it says.
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Disregard this, looked at the wiring diagram and this is apparently legitimate.
 
That red w/ white wire with the fiberglass sleeving looks crappy on yours that goes to the 4 pin connector and eventually to the red 6 pin connector. Extract that terminal inspect. It's a common failure point on these.
 
Maraakate said:
That red w/ white wire with the fiberglass sleeving looks crappy on yours that goes to the 4 pin connector and eventually to the red 6 pin connector. Extract that terminal inspect. It's a common failure point on these.
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Don't worry this is not my working harness, this is the original "hack job" harness from when the PO could not get the bike started. I kept it so I can rebuild it someday

"WE CAN REBUILD HIM" remember that show?
 
No never watched that, sorry.

I was contemplating doing a run of new harnesses for sale but it's been on hold due to other priorities and I'm unsure of interest. If it became a reality it would be somewhere between $100-$150.
 
Fyi Tom, search eBay for SH232-12. It was used by Kawasaki in bikes up until 2009 so you can get a modern one. The only difference is the canon plug is different so you'll have to extract them with a pick tool and move it over to the other one:

www.ebay.com

Kawasaki 21066-1030 for sale | eBay

Get the best deals for Kawasaki 21066-1030 at eBay.com. We have a great online selection at the lowest prices with Fast & Free shipping on many items!
www.ebay.com
 
LongDistanceRider said:
Check your battery input(Red wire) to the Ign switch and output on the Black wire, should match up.
I haven't installed the Mosfet unit on your model, fit fine on the CM version with some mounting hole mods.
Looking at a picture of the CB I think it'll fit fine


Randy posted the dimensions here https://roadstercycle.com/Shindengen FH020AA mounting dimensions.htm
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It was exactly 4 years ago today you posted about the Mosfet unit. I later read that and thought, maybe overkill? Now, I realize that you had the best solution to this overcharging chronic problem.

Upgrades to the Charging and Ignition system

As with all the vintage Honda motorcycles the charging system leaves something to be desired. Add to that the 35-40+ year old CDI ignition system and it's expensive pieces. This is not a cheap fix for any of the above but it is a solid reliable cure for them. IGNITION: Replace the CDI with this...
www.vintagehondatwins.com www.vintagehondatwins.com
 
esmith250624 said:
I Understand. You can't chase it forever. I really want to know how that black wire in the regulator connector connects back to the harness. it is the one connection point that I could not put my eyes on. I have an old wiring harness that is already unraveling, so I am going to go look to see how that connects.
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Yes, the black wire seems insufficient to provide enough voltage to trigger down regulation. You tested without the headlight too. With headlight on, there was a huge voltage drop.
Old Fart (Mike Nixon) just posted in his garage series, a comment about band-aid fixes mentioning headlight relay set ups as one of those. I don't know if this case might be an exception for an alternate strategy to overcome this chronic issue.

Regardless, I'm realizing that Jim's Mosfet mod is the best margin of robustness to protect the battery and I won't have to rebuild the harness or worry about incremental degradation of the many parts of that regulation system (key switch, wiring, connectors, lighting loads, etc.).
 
ancientdad said:
No worries. Yesterday I was trying to decide if I needed to turn it into a Project thread, figured I'd wait for things to shake out.
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LOL. I know, but you do a great job of thread herding here.
This bike project started with my last post at the old place, then mostly completed before I joined here, so I never thought it should have a build thread here.

As editor extraordinaire, I back whatever you do, from a relocate to title addition.
I could just end and redirect to Jim's post (above link) to finish with a Mosfet upgrade.
 
ballbearian said:
I could just end and redirect to Jim's post (above link) to finish with a Mosfet upgrade.
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We'll figure it out soon enough, and it isn't a big deal really. My pet peeve is when I ask that someone start a new thread for their repair needs and then others come along and discuss the repair right there in the OP's introduction.
It was exactly 4 years ago today you posted about the Mosfet unit.
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I'm normally more awake than that, but this is our first milestone that got past me completely.

3 days ago VHT was 4 years old. Yay.
 
I went ahead and ordered the Mosfet from Sparck Moto.
Then this thought occurred to me.
ballbearian said:
What do you think of connecting the sensing wire to the battery itself?

EDIT: Duh. It wouldn't be switched! Maybe I'll go back and check the red from battery to key switch.
Click to expand...
What if I took the black wire out of the connector to the rec/reg and taped it off, then ran a new black from that connector directly to the battery positive?
Or just jumpered from that black connection to the red/white feed from the rec/reg?
 
The theory behind the black sense wire is to allow the regulator to compensate for voltage/load draws. As the voltage thru the ignition switch is stabilized by bringing the battery up to full charge the regulator dumps more off rather then charging the battery. Quite possible doing a direct battery connection would work, never tried it.
 
LongDistanceRider said:
The theory behind the black sense wire is to allow the regulator to compensate for voltage/load draws. As the voltage thru the ignition switch is stabilized by bringing the battery up to full charge the regulator dumps more off rather then charging the battery. Quite possible doing a direct battery connection would work, never tried it.
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Thanks for confirming my current ( :p ) level of understanding.
I just might play with this idea, after another running test with headlight unplugged to see if the regulator can be coaxed into action, before giving the direct connect a try.
 
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