1980 CB900F Build

Nope. Installed the battery and checked volts, 12.79V so far so good. Turned bike on to idle and it dropped to 12.38V held the revs at 3000 and it stayed on 12.38V. So no magic fix today. The reg/rec has its own earth bolt to the frame to make sure its grounded good and proper. The purple wire that shares that ground is the oil temp sender earth. I checked that its getting some AC current to it but don't know how much it should be getting so that doesn't really answer anything.
There is a pic of the earth for the crank case, big thick wire straight from the neg terminal of the battery.
Also last pic is of the earth block for all the front lights and switches. As I said, not really proud that its just tech-screwed in but its a solid earth that doesn't rely on the bearings in the head stem to be making contact.

Sooo.... why isn't it charging?
 

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So I have done some reading and followed everyone's fault finding guide and I'm starting to think my Reg/Rec is not working. I pulled apart the only 3 original plugs from the wiring loom and cleaned the male and female connectors up with emery paper and pinched the female sides closed a little bit more with my long nose pliers. (pictured) After that I reassembled the plugs and was even a little bit happy with how well they clipped together, but after starting the bike and getting nothing but battery voltage out of the Reg/Rec output side i'm pretty sure that's where the problem is.
I did check the resistance of the stator slip rings and the continuity and they were all good. Seeing as its only a $25 part i'm just going to see if the one motorbike shop in this town has one in stock. (pictured)

Also I have to look into what dielectric grease is and where to get it.
 

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check the resistance on the charging rotor

and inspect the brushes if they do not have good continuity thet reg cant energize the rotor

make sure they meat left and are not sitting at the replace mark

what was the resistance of the rotor?

if you are stuck i probably have a few airboxes from where i swapped carbs on mine
 
It's a long time since I worked on 750/900 (mid 1980's) Pretty sure the earth is under one of the rear case bolts then onto frame either on a tapped hole in lower rear engine plate or under a bolt head? ( I would have to dig out a manual to check)
Generator rotor could be suspect, they are very reliable but don't like being smacked about (do any of us? ;D )
I only read about the cover damage this morning (it's 8.54am in Florida)
Did you get correct instructions with battery? Let it stand a minimum of 1 hr but preferably 24 hrs, check voltage and charge at 1/10 of capacity for 12 hrs or max charge rate printed on it somewhere for 1~3 hrs (may be on instruction sheet.
SLA has a slightly 'more acidic' acid than conventional 'wet cell' ( from memory I think 1.32sg instead of 1.26~1.27sg)
 
Tim of all trades said:
Also I have to look into what dielectric grease is and where to get it.

Dielectric grease is an insulator. It can not make your connections better. It can make them worse. I know there is controversy over the stuff. It's good for lubing o'rings, otherwise, I have little use for it.
 
CXMAN asked the resistance of the rotor. Good question. It should be about five ohms. You'll have no field if it's shorted, just a dead battery. I'm not familiar with your Honda, but from my chair I'd ask if a shorted rotor could damage the regulator. Measure slip ring to slip ring.
 
It's an EMF system, so shorted rotor could damage reg/rect as it will try to power field coi,l not get expected~14v so allow full battery voltage. As it's voltage regulated not current regulated it shouldn't be possible to overheat windings with a dying battery. If you connected a car battery up with engine running, that could easily supply enough amps @ around 15v to fry things.
I'm guessing $25.00 is price of used part?
 
Thanks for the help fella's, to answer a few questions the brushes have a fair bit of meat left on them as seen in the pic and there is no resistance between them and the bolts holding them in. I know the pic I put up here says 4 Ohms but thats because I was holding it in one hand to take a pic and couldn't get a great connection, but with two hands it was definitely 0.
The resistance between the slip rings on the generator rotor is 4.3 Ohms and from memory that within range?
Also resistance between the stator coils is 0.4 Ohms which is inside the allowable 0.4 to 0.5 range. and I checked all 3 yellow coil wires not just the one pictured.

Who would have known this would be so much fun!
 

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crazypj said:
It's a long time since I worked on 750/900 (mid 1980's) Pretty sure the earth is under one of the rear case bolts then onto frame either on a tapped hole in lower rear engine plate or under a bolt head? ( I would have to dig out a manual to check)
Generator rotor could be suspect, they are very reliable but don't like being smacked about (do any of us? ;D )
I only read about the cover damage this morning (it's 8.54am in Florida)
Did you get correct instructions with battery? Let it stand a minimum of 1 hr but preferably 24 hrs, check voltage and charge at 1/10 of capacity for 12 hrs or max charge rate printed on it somewhere for 1~3 hrs (may be on instruction sheet.
SLA has a slightly 'more acidic' acid than conventional 'wet cell' ( from memory I think 1.32sg instead of 1.26~1.27sg)

Instruction with the battery were "The instructions are inside" I read it and it said it only needs 20 mins for the electrolyte to flow in then its good to go. I did think there was more to it than that. Now I know for next time.
 
Yep, that's battery sellers instructions.
Doing things that way (seen it before) battery can fail in as little as 3 weeks.
I doubt you've done any damage so bung it on a slow charge for 8~10 hrs at 13.7~14.2v @ 0.5amp max charge. If you only have a 'fixed' output charger, get a cheap timer (probably already have a few, most people do for Christmas lights, etc?) give 20 min 'zap' with 10 min cool down for a few hours
 
The local bike shop didn't have a rectifier and the guy said to go after market anyway because the OEM one was $439. But they did order the brake rebuild parts I needed.
So... its going to be a good ol fashioned thumb twiddling until I get me some more parts, but I will keep you updated.
 
make sure none of the stator legs have continuity to ground

same with each side of the rotor
 
Tim of all trades said:
The local bike shop didn't have a rectifier and the guy said to go after market anyway because the OEM one was $439. But they did order the brake rebuild parts I needed.
So... its going to be a good ol fashioned thumb twiddling until I get me some more parts, but I will keep you updated.

http://www.oregonmotorcycleparts.com/ Oregon Motorcycle Parts probably has what you need, plug-n-play.

ompround.jpg
 
Tim of all trades said:
Who would have known this would be so much fun!

LOL, AS Benny Hill said in one of his comedy sketches, 'Learning All The Time' (while groping one of the almost supermodel actresses)

There are a few R/R that will work. Either get a brand new aftermarket (generally better than OEM as they use higher quality or MIL spec components) or get RR from Honda SOHC 350~7500F, Yamaha XS 650 or similar or Kawasaki.
Anything with 7 wires should work, stay away from 5 wire RR as it won't ave a control feed to field windings. I'm pretty sure you won't find anything from Suzuki as tey used car style alternators on EMS systems and of course, a 5 wire PMS won't work. have you tried 'full fielding' the field windings? (basically connect te white wires direct to battery, you should get around 17v at idle. Don't rev the engine as voltage can go crazy high (100+ before it all goes quiet and the magic smoke leaks out)

jetmechmarty said:
http://www.oregonmotorcycleparts.com/ Oregon Motorcycle Parts probably has what you need, plug-n-play.

ompround.jpg

Two way shipping may be a bit expensive from 'Horsetrail-yee-haa'
 
crazypj said:
have you tried 'full fielding' the field windings? (basically connect the white wires direct to battery, you should get around 17v at idle. Don't rev the engine as voltage can go crazy high (100+ before it all goes quiet and the magic smoke leaks out)

Two way shipping may be a bit expensive from 'Horsetrail-yee-haa'

What? as i'm not 100% on what that is I will just wait until I work out a new rr. and yeah postage to this side of the globe gets a bit pricey... not to mention the AUD is only 80c to every USD.
you said there are a few 7 wire rr that work but mine has 8 wires, which wire can I not use/direct elsewhere?

Also 'Horsetrail-yee-haa' hahahaha! your killing me!
 
I think original has dual grounds? I still haven't looked for manual. I 'll try and get a look at it tomorrow
I'm from 'old' South Wales, saw NSW on number plate and knew it didn't mean
'Not Safe (for) Work' ;D
Full Fielding is where you figure out which wires are going to the brushes and connect them direct to battery. That will make the electromagnet ( the 'EM' in EMF) as strong as it's ever going to get. Your bypassing the regulator which is why I said only check at idle (generally OK to about 1,5~1,700rpm) It's so long since I had to do it on CB900 I can't remember results if you get over 2,000 rpm, maybe just the instrument and head/ tail light 'pop'? (that's the minimum damage)
 
crazypj said:
I think original has dual grounds? I still haven't looked for manual. I 'll try and get a look at it tomorrow
I'm from 'old' South Wales, saw NSW on number plate and knew it didn't mean
'Not Safe (for) Work' ;D
Full Fielding is where you figure out which wires are going to the brushes and connect them direct to battery. That will make the electromagnet ( the 'EM' in EMF) as strong as it's ever going to get. Your bypassing the regulator which is why I said only check at idle (generally OK to about 1,5~1,700rpm) It's so long since I had to do it on CB900 I can't remember results if you get over 2,000 rpm, maybe just the instrument and head/ tail light 'pop'? (that's the minimum damage)

ohhhhh, that makes sense now. I'm still not gonna try it. My Brother lives a couple hours away in a bigger city and the motorcycle shop there had a rr in stock for $80. I'm going to his place next weekend because us Aussies celebrate "invasion day" next Friday. So when I get back if thats plugged in and things still aren't working I will look in to more drastic measures.
It was 40 degrees hear again today and its going to be hotter over the weekend. So I will be avoiding the garage for a bit.
Where is South Wales? Florida somewhere?
 
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