airhead charging system not working

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airhead charging system not working

Postby RocketMan » Fri Apr 26, 2013 8:01 pm

I went for a short ride today today and noticed the volt meter i installed was not showing the normal charge rate, in fact it showed a slight decrease when running, down from 13+ to about 12.2 when at idle and 11.9 when running above 2000 RPM. Voltage went up to 12.4 with bike off. Got home and checked battery, fully charged at 12.4 across terminals and same between + and any good engine ground. Bike starts and runs fine but no voltage increase at battery when rev'd. Disconnected everything 'cept large red wire at battery and same thing. Lights are working at full brightness and dash lights come on when key is switched on, except for the Red charging light which just lights dimly and remains dim at all RPM's.
So given the gen light only glows dimly but rest of lights glow bright, alternator or diode board? or wiring from Alt to diode board or between diode board and starter to battery? Not sure how to check alternator but can look for voltage at DC output of diode board and for shorted diodes.
Check brushes as well I guess but not sure beyond that.

thoughts on what needs replacing/repair?

the one good thing about this is that had I not installed the voltmeter i would not have known I had a problem until the battery ran down and bike quit in the middle of some nowhere place since in the daylight I could not see the dim glowing of the charging light at speed and that it did not light brightly at idle ( which it normally has not been doing anyway, but since the voltmeter showed normal increase to 13+ volts above idle I figured that my idle was a bit high).
Anyway the voltmeter has paid for itself already for sure!!

RM
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Re: airhead charging system not working

Postby Genen8kua » Fri Apr 26, 2013 10:44 pm

13 is a fair charging voltage, 13.8 would be better. Less than 13 & (assuming something's not drawing a *lot* of current) ain't enough. What's clear from your voltmeter is that you're not getting adequate (or any) current/voltage from your charging system. If your battery was fully charged when you hit the starter, it would've been at about 12.8v. When running, there's a voltage drop across the battery, which is why your voltmeter reads 12.2 at idle and less at higher rpm (because you're drawing more current to run the bike faster). Usually the charging system makes up the difference. When you returned after your ride, you had 12.4v, which is about 80% of a full charge.

Spurred on by your puzzle, I found a heady article about Bosch charging systems here which nicely explains how the system works (been meaning to learn about that) and how the idiot light works. Seems your symptoms could be the result of a bad rotor, brushes or a bad voltage regulator (or maybe diode board).

One can hope that nasty corroded contacts could be causing problems. Praeger's MOA article on charging system maintenance might be a place to start. The ibmwr.org site has some nice airhead tech articles about charging system problems & a couple ways to investigate the diode board, assuming you know (or want to learn) your way around a multitester. If you have a Haynes manual for your bike, that may have a test procedure too.

Alternately, make sure every connection in the system is pristine (per Praeger's article), see if that fixes it, and if not seek professional help from there.

Important tip: you've partially discharged your battery - I'd hook it up to an appropriate charger. Otherwise sulfation will shorten its life. Overnight on a tender could probably do it. If you do need to ride it to a shop, you'll want as much battery as possible (& might want to disable your headlight - and ride extra defensively - for the trip too).

Maybe we'll hear more at Sunday breakfast.
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Re: airhead charging system not working

Postby RocketMan » Sat Apr 27, 2013 7:02 am

Ok, just to clarify, prior to this last ride the bike had been on a tender and was reading 13.1V when connected, which generally drops to 12.8 when disconnected.
during any previous ride the system would charge at anywhere from 12.8 to 14.1 at speed, depending on RPM and electrical load and would drop to 12.4 or +/- .3v, at idle and read 12.6-12.8 when turned off, so up until yesterday it was charging just fine and would go to full charge within an hour of being put on the tender.

and I actually do know something about electrical energy and how the various components work, such the alt, rectifiers, resistors, transistors and such having work for a home study electronics school years ago and even designed and built a simple circuit board and acted a test student for some of the courses to help ensure the directions were clear and correct by building some of the equipment as part of the courses. So I do know how to check the diodes which are basically one-way pass filters and will look for corrosion in the circuit from the alt to diode board to starter and battery. My biggest problem is that with this (as many other similar things, I'm better at theory than application!)I did read Gary's tech page on charging systems and noted he says if the gen light does not come at all when the key is turned its either the bulb or the alt. But what I found to be significant is that it does lite (although dimly) with key on - engine off, and doesn't seem to change in intensity while operating (or go out completely as it should) and also that there is a delay of about one second between the time the key is turned and the gen light starting to glow while the other lights for neutral and oil come on immediately, as they should. So I'm thinking this may well mean something significant to someone knowledgeable on airhead charging systems which would point to a most likely or probable cause based on their past experience.

Luckily for me some kind person has been parking a nice little Honda IT700V in my garage so i have another ride (once I figure out how these Japanese bikes work! :lol: ) and plan on heading up to Bob's today where I am sure I will find plenty of experience and some further info on what to check and what to expect such as the winding, brushes, regulator and diode board.

Worse case I ride it down to Khanh's place which I know it will get to even just running off the battery with only essentials turned on. Nice thing about a '75 /6 is that it has a switch that allows can turn off the headlight and front parking light. Hell, I once road my R100 for two days and some hundreds of miles with nothing more than (mostly) battery power due to the diode board mounts having broken and the main wire on the +DC side having many broken strands since the board was mostly just dangling from that inside the cover!

So anyone with thoughts to odd behavior of the gen light?

RM
Last edited by RocketMan on Sat Apr 27, 2013 7:42 am, edited 1 time in total.
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Re: airhead charging system not working

Postby Shane R1100GS » Sat Apr 27, 2013 7:38 am

It's sounds like the rotor. You need to slide a piece of paper under the brushes and check with a ohm meter. It should be some where between 3 ohms and 7 ohms.

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Re: airhead charging system not working

Postby RocketMan » Sat Apr 27, 2013 7:47 am

Shane R1100GS wrote:It's sounds like the rotor. You need to slide a piece of paper under the brushes and check with a ohm meter. It should be some where between 3 ohms and 7 ohms.

Shane


yeah that's what my reading has led me to think as well. One other odd thing though is that during my tests yesterday, 5 or so, one time when I turned the bike on and ran it up to speed, the charging at the battery did go up, though not to full (being 13.6+) but just to around 13.2. All other test run I saw no increase, period. So perhaps its bad wiring/corrosion/lose wiring in the charging circuit. but we shall see.

RM
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Re: airhead charging system not working

Postby Shane R1100GS » Sat Apr 27, 2013 8:05 am

I have a charging system from my GS I'm not using if you need it. I just checked and rotors are the same. Bob's wants $450 for a new rotor.
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Re: airhead charging system not working

Postby Genen8kua » Sat Apr 27, 2013 9:05 am

Hmm, so I guess the rotor hypothesis is rising; if I'm understanding this well, the current path when the bulb (properly) lights brightly runs through the rotor. This also magnetizes the rotor, and (I just read) if there's no bulb current, charging can be hit or miss. Wouldn't it be lucky to have a problem with the idiot light circuit causing this? This page has a nice description of how the idiot light works and how, if the rotor is bad, there's only a much higher impedance path to ground and the bulb will be dim. Corrosion or a semiconductor problem could explain the delay in the light: someting might need to heat up, or you could have the equivalent of a time constant circuit (resistor in series with a capacitor) that introduces a delay.

Here's an offer: I'm on the fence re: the breakfast ride to Nokesville. I'm PMing my cell phone # to you and Shane. If you make arrangements re: the rotor, I'll move off the fence and plan to go. I'll be at Bob's open house later this morning, at That's Dancing at Route 1 and Guilford tonight & could likely meet up with Shane some other time today (I'm in Ellicott City, Shane's in Laurel) and relay the rotor to you tomorrow morning.

BTW, didn't mean to insult your 'lectrical knowledge - I'm pretty good with such stuff, but took your problem as an opportunity to help fill my own knowledge deficit about charging systems. In the past I've started to help someone through a trouble shooting process and have had eyes glaze over. Listen to Shane, he seems to have been there.

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Re: airhead charging system not working

Postby RocketMan » Sat Apr 27, 2013 7:58 pm

Genen8kua wrote:Hmm, so I guess the rotor hypothesis is rising; if I'm understanding this well, the current path when the bulb (properly) lights brightly runs through the rotor. This also magnetizes the rotor, and (I just read) if there's no bulb current, charging can be hit or miss. Wouldn't it be lucky to have a problem with the idiot light circuit causing this? This page has a nice description of how the idiot light works and how, if the rotor is bad, there's only a much higher impedance path to ground and the bulb will be dim. Corrosion or a semiconductor problem could explain the delay in the light: someting might need to heat up, or you could have the equivalent of a time constant circuit (resistor in series with a capacitor) that introduces a delay.

Here's an offer: I'm on the fence re: the breakfast ride to Nokesville. I'm PMing my cell phone # to you and Shane. If you make arrangements re: the rotor, I'll move off the fence and plan to go. I'll be at Bob's open house later this morning, at That's Dancing at Route 1 and Guilford tonight & could likely meet up with Shane some other time today (I'm in Ellicott City, Shane's in Laurel) and relay the rotor to you tomorrow morning.

BTW, didn't mean to insult your 'lectrical knowledge - I'm pretty good with such stuff, but took your problem as an opportunity to help fill my own knowledge deficit about charging systems. In the past I've started to help someone through a trouble shooting process and have had eyes glaze over. Listen to Shane, he seems to have been there.

Gene


No insult taken, just wanted to clarify what I know and don't which like I said, great at theory lossy at application!

and tanks for the offer to transport rotor, which I got from Shane and have installed, after some head scratching.

RM
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Re: airhead charging system not working

Postby RocketMan » Sat Apr 27, 2013 8:24 pm

So I got a rotor from Shane and got it installed, after some head-scratching as to getting the cover off the rotor. Found there was one wire coming thru the cover that had to be removed with the lug then found that the three wires coming thru th bottom hole were preventing the cover from coming off far enough to get the cover swung out of the way. Hmmm, since they were soldered to the small board and that board was in no way going to fit thru the hole the wires route thru I'm thinking WTF??? So I detached the small board they were soldered to the screws being real stubborn (can you say WD-40???) and then found that by removing the board I was able to fiddle with the three wires enough that the cover came down far enough to clear the rotor. Then of course the rotor bold would not come free. Tried wedge something thru the rear wheel with the bike in gear, and well can you bent/cracked spoke? Garn! then I got Jeanne to sit on the bike as far back on the seat as possible and got the bolt to break free. From there the rotor cam free with the removal bolt and new one in place. cleaned all the contacts as best as possible, buttoned everything back up and the gen light lit bright with the key turned on. Fired her up and Damn ran like crap. bucked and tossed and sometimes acted like the start motor was freezing up! Oh Great! So I checked the timing as tthe bike acted like it would with timing way off (although I did nothing to timing adjustment and sure enough it was way off. The S line was nowhere near the window. Having never timed a Dyna before and noting the plate does not have the little adjustment slots like the points system I was stuck.

I did find a manual online for it, seems the plate doesn't move the pickups do, and each side is adjusted separately for each cylinder. Oh, Great! So now I have find out which way on the flywheel is advanced and which retarded and then try to adjust them.

To make for a full day of Oh Shits, when I stopped on my way home to get a cool drink, and when I went to start the Honda, the Check Engine light came on it wouldn't start! Oh Great, even better! I did finally get it to start and rode the rest of the way home with it dimly glowing (dimly glowing lights seems to be a thing with me this week!); it seemed to run just fine, dimly glowing engine and all. Got home, parked it, turned it off then back on, engine light came on first time but started just fine. second try the light came on then went right out like its supposed to do and after a half dozen cycles, no more light or issues.

So I guess I will be caging it to the Bfest meet tomorrow and will have to see if I can round up some help with the dyna timing or struggle thru it all by my lonesome and do even more evil things to my airhead!

Some days you just can't win.....

Thank Dog for cold beer!

RM
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Re: airhead charging system not working

Postby Georgeinva » Sun Apr 28, 2013 1:19 am

Before you waste any money "fixing" the charging system take a look at this. http://www.euromotoelectrics.com/produc ... altkit.htm It is not a quick or easy fix but you will never have to worry about the charging system again.
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Re: airhead charging system not working

Postby Shane R1100GS » Sun Apr 28, 2013 7:09 am

Make sure you didn't pull a throttle cable out of it's holder on the carb.
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Re: airhead charging system not working

Postby RocketMan » Sun Apr 28, 2013 7:36 am

Georgeinva wrote:Before you waste any money "fixing" the charging system take a look at this. http://www.euromotoelectrics.com/produc ... altkit.htm It is not a quick or easy fix but you will never have to worry about the charging system again.


I think you forgot to add "Which I would be happy to install (for a price, of course!)" :lol:

This is something I was planning on doing this fall but unless this advice comes with an 8 month no -interest loan current budgetary constraints prevent me from ponying up the cost for that at the moment. :lol:

what I can't figure out is why changing the rotor would affect the timing. The timing mark does not appear anywhere in the window like it should, very odd. May have to try a static timing but the directions for the dyna as somewhat unclear, when it says the "leading edge of the magnet should be near the center of the pickup" I can't see any obvious "leading edge" on the magnet which is a round solid unit and therefore as no "leading edge" that I can see. There is what appears as slight bump between the two retaining set screws which is perhaps what they are referring to. So I'm hoping I can find a better writeup for the dyna other than the manual.

Stay tuned....

RM
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Re: airhead charging system not working

Postby RocketMan » Sun Apr 28, 2013 7:55 am

Shane R1100GS wrote:Make sure you didn't pull a throttle cable out of it's holder on the carb.


Funny you should mention that as i was planning on re-routing the cables anyways. The way it is routed now creates quite a sharp bend between the throttle and triple tree and makes it rather harder to twist than it should be. I have the 2-into-1 cable setup because i switched to the dual disk setup and used an assembly from an R65 which accepted the 1975 switch gear so I would not have to replace that and it appears I have plenty of cable run length to play with.

Oh, the joys of airhead ownership..... :lol:

RM
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Re: airhead charging system not working

Postby RocketMan » Sun Apr 28, 2013 7:19 pm

So after getting home from the breakfast meet I tackled the timing issue again and found that after I adjusted the base plate for the Dyna all the way clockwise I got the bike running smoothly, still advanced but no hiccups, backfiring and the advance mark came into view around 22-2500 RPM. Base plate is maxed out in the clockwise direction and since I still can't get the advance unit off the shaft to adjust the magnet on the camshaft I'll just have to adjust the two magnets on the base plate individually both of which i found to have lose lock screws. Naturally the only 6mm wrench I had was a 12 point box that wouldn't fit under the advance units fly weights so I ground one side of a 5/16 open end slightly and got them tightened down. Now for some reason the PIAA lights don't come on with the high beam even though the Aux switch lights when the high beam goes on so... have to look inside the headlight and find out whats going on, blown fuse most likely but we shall see.

A big thanks to Shane for loan of the rotor, once again the group comes through with help without question; you guys are bestest!

RM
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Re: airhead charging system not working

Postby Unity » Sun Apr 28, 2013 8:39 pm

Jeez, Jeff. At least you're not at the side of the road in Wyoming.

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