Yet more charging problems

widget
Posts: 164
Joined: Wed Apr 14, 2010 10:28 pm

Re: Yet more charging problems

Post by widget »

Thanks for the reply.....How do i check that?....do i put a meter onto each brush in turn and an earth?...and what colour wire is the other one?.....complete numpty at electrics :o
teazer
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Joined: Mon Mar 07, 2011 8:10 pm
Location: Chicago

Re: Yet more charging problems

Post by teazer »

Yes, At the alternator, one brush lead comes from the Regulator and the other goes to ground. Green is the one from the regulator and should not exceed about 12v. The other brush goes to ground.

Normally, we would expect the regulator to have a sensor voltage of 12v +/- a couple. The problem on that side is that the lead comes from the coils which come from the run/kill switch which comes from teh keyed main switch and there is usually a voltage drop across that circuit that cause the regulator to 'think" that the battery is flat , so it allows more power to the rotor to bring the voltage up. That line is typically 11.5 volts or less witha good system because of poor connections.

Some people add a relay to that circuit so that the regulator is sensing "real" battery voltage rather than fake battery voltage. So that is the first place we usually try to fix.

If that is the situation on your bike it is possible that the regulator is allowing excessive voltage to the rotor. We all know that's not normal and that's why I suggested that you check it.

The rotor is fairly simple and the usual causes of failure is breaks in the wire from old age and hardening wires and connections or breakdown in the insulation allowing coil wires to touch and short out. New rotors should not have that problem IF they are correctly re-manufactured.

One question that remains on your wife's bike sis what is the more of failure. Do the failures appear to me mechanical i.e. breaking or electrical (overheating)? If they appear all to be mechanical, and after leaving out those rewinds with loose wires, what could be the cause? The most likely in my mind is vibration. For example if a main bearing is failing or the right bearing is loose, maybe it's vibration that is the issue. That could be a low frequency shake or a high frequency buzz and may not necessarily be obvious to the rider.

So let's try to rule out electrical causes first.

After that you might check and recheck carb synch, ignition timing and plugs and leads to eliminate those one at a time.
widget
Posts: 164
Joined: Wed Apr 14, 2010 10:28 pm

Re: Yet more charging problems

Post by widget »

Thanks for the reply, i do appreciate people taking the time to post on this....will have a look at it with the meter one evening this week....

Vibration had been mentioned before, though the bike doesn't appear to be buzzing.Will see if i can clock the taper with the bike running. timing is spot on, got new lectric ignition and clocked it and strobed it..Has had new plugs...

Two rotors have had broken wires, and there was the one with the moving coil, though was that caused by heat or vibration?......The last rotor that went had broken wires and had only done 30 miles on her bike after being on mine for 5 years...Would have thought that for vibration to do that, it would be very noticeable... or not.....

Not going to rule anything out, but would love to find 'the cause'...
widget
Posts: 164
Joined: Wed Apr 14, 2010 10:28 pm

Re: Yet more charging problems

Post by widget »

right...put a meter on the green wire going to the brush...at tickover 11.4v....rev it up and goes a bit varied...12.2-13.1 tried it several times and got the same....

The readings did vary a bit....from 10 ish to 13.1.....
teazer
Posts: 1035
Joined: Mon Mar 07, 2011 8:10 pm
Location: Chicago

Re: Yet more charging problems

Post by teazer »

While that indicates that maybe the sensor lead should be modified to get a cleaner signal of actual battery voltage to the Regulator, it seems to suggest that the rotor(s) are not getting excessive voltage. So at that point, it suggests that the problem is mechanical. The loose wires were manufacturing faults as was the loose core, but the last one that lasted 30 miles is the puzzle. Was it already old and fragile and ready to pop.

I'd like to see that bike on a dyno revving under load with a vibration measuring tool attached. Not something I have ever tried but I guess we are looking for amplitude and frequency

Something like: https://www.keyence.com/landing/measure ... aQodRCMAJA

Or similar might be the tool to use. Of course if you prove it is in fact vibrating, that raises the question of whether your particular bike vibrates more than the average and that requires the measurement of multiple engines which might not be so practical. And after proving that either the amplitude or frequency of vibration is more - or less- than normal, it still has to be fixed.

I think at this point, I would try another "pre-loved" rotor or get one rewound nice and tight and with the wires epoxied together to stop them from moving and see if that lasts any better.

Others will suggest getting the crank balanced or getting the rods balanced end over end and replacing the rubber mounts. If thew motor was ready for a rebui8ld, I'd agree with those, but on a rebuilt motor, I'd start with a good strong rotor and see if that will work. Good luck with it.
widget
Posts: 164
Joined: Wed Apr 14, 2010 10:28 pm

Re: Yet more charging problems

Post by widget »

Just put on a freshly rewound rotor...wires are well stuck down.........Going to have another check of connections and see what happens....
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Waterbuffalo
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Re: Yet more charging problems

Post by Waterbuffalo »

Its things like this that are one of the reasons I rebuild and upgrade the stock wire harnesses. Theres just too many areas of dodgy design begging to be upgraded.
Two strokes, its just that simple.
widget
Posts: 164
Joined: Wed Apr 14, 2010 10:28 pm

Re: Yet more charging problems

Post by widget »

I was really hoping to find some 'burnt bit'.........don't think i will be that lucky.... :cry:
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Waterbuffalo
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Re: Yet more charging problems

Post by Waterbuffalo »

After re-reading all your posts I'm still a bit stumped as to whats really going on with your rotor issue. So heres a question for you have you removed the electrical panel and looked behind there to make sure the alternator wires (three yellows and the green) are not rubbing on the inner lower metal section of the rear fender? If they rub long enough they chafe off the insulation and create a shorting to ground situation there thats intermittent.
I had such issues there on one bike and only found it when pulling the rear harness out to rebuild it. Two of the points wires were rubbed through which caused the bike to drop cylinders at random, and two of the yellow phase wires were rubbed through which caused me to blow up a rectifier. Its not a constant short due to the vibrations when the bike is running which made it hard to trace initially. The photo shows what was going on with the three phase wires just behind the panel.

Image
Two strokes, its just that simple.
widget
Posts: 164
Joined: Wed Apr 14, 2010 10:28 pm

Re: Yet more charging problems

Post by widget »

Had a similar prob on mine with the wire from the electronic ignition chaffing through...big problem in the wet but fine in the dry....Took ages to find...

I will be replacing the genny, but will check any wires i remove...so longing to find a fault.....
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