Non charging issues

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stinkywheels
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Joined: Thu May 02, 2013 9:25 pm
Location: Sutton Coldfield, West Midlands

Re: Non charging issues

Post by stinkywheels »

Evening Alan
Thank you for your email.
DK spares have 2 rotors and I was going to take my meter with me before buying if they do measure a higher resistance than mine.

I need to run the AC test as you have put forward as I can see if I measure the 20V it cannot be the rotor or stator. I am puzzled as I checked the rectifier on diode setting and had a measured the same resistance one way across each diode and infinity the other way leading to me believing the rectifier is ok. I checked the regulator in accordance with suzuki spec and it checked out I physically moved the two contacts closer and further away from each other an the resistance on the meter changed at the same time - from this I have assumed the VR coil and the mechanical movement are operating as they should. I checked the two fixed resistors on the reverse side of the VR and they each gave a resistance reading so I conjected that they were not open circuit.

I checked the slip rings and the green supply lead to for direct short earth and confirmed that the circuit is definitely not conducting. In that process I checked the insulating "top hat" on the positive brush and that proved to be fully insulating. (Although I have chased points before now which ended being a hairline fracture of the insulating washer)

Until I measured the low resistance across the slip rings I was going to buy a electronic VR rectifier from Electrex world - RR7 thinking the VR was at fault. These are not cheap at £90.

After I have run the AC test Would it be possible to give you a call if still no measured charge ?

Also the positive rotor brush is close to the wear mark, I have checked the resistance from the brush to the rotor and it's pressure is still making good contact. The brushes for the Kokosan are a staggering price - if you can get them. Do you know if Is there an alternative from another make of bike or car I can use or modify to fit? The Denso brushes are available at £14 .00 and I thought about buying a pair filing the brush down to size and soldering the tail back onto the brush mounting plate. I am assuming at least the brush grade from the Denso is probable closer to the Kokusan than from another source.

Greatly appreciate your help


Regards
Paul.
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Alan H
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Re: Non charging issues

Post by Alan H »

Easiest way to test the rotor in situ, is to lift both brushes and put a bit of dry card between each brush and the rotor. Now test (on ohms) between the tracks on the rotor, and between each track and earth (anywhere nearby on the engine cases will do) unless the reading between tracks is very low, it should work, too low, and it will work less effectively - try a steel screwdriver against the rotor with ignition and kill switch on - (aforementioned card removed, of course).
Now remove the card and disconnect the green wire from the rotor - you can actually do this by parting the regulator plug & socket. Then test through from green wire to earth. This will ensure a circuit through the rotor.
From your observations, it appears that rectifier and regulator are working.
I've had 'issues' with brushes on my 550s and 750, and just measure them lxbxw and look on ebay for something similar or slightly larger - I used ebay 254932351583 5x8x20mm at £5.50 a pair and carefully filed them to fit,
Proof that four strokes are over complicated
teazer
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Location: Chicago

Re: Non charging issues

Post by teazer »

Do the tests as Alan suggested, but as a point of reference, I have a few GT750 rotors and they are all either 5 ohms or 10 ohms +/-1.

If your regulator and rectifier are OK, keep them, but if not I had success with a solid state unit from Electrexworld. No issues with it and voltage nice and steady.
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Alan H
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Re: Non charging issues

Post by Alan H »

Another thread on electrickery - viewtopic.php?t=12685&hilit=Rectifier
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stinkywheels
Posts: 26
Joined: Thu May 02, 2013 9:25 pm
Location: Sutton Coldfield, West Midlands

Re: Non charging issues

Post by stinkywheels »

Hi Alan
Pleased to say the replacement rotor and the replacement rectifier have the bike now charging at 13.5v at 3000 rpm and climbs to to 14v plus regulated as the revs rise.

Is there anybody who can rewind the original rotor?

Thanks again
Paul
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Alan H
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Re: Non charging issues

Post by Alan H »

Glad it's sorted. Did you use the new rectifier straight away, or did you try it with the original first?
stinkywheels wrote: Sun Jan 16, 2022 5:37 pm Is there anybody who can rewind the original rotor?
Never heard of anyone doing them tbh.
They're cheap enough and I've got a couple more anyway..... :lol:
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stinkywheels
Posts: 26
Joined: Thu May 02, 2013 9:25 pm
Location: Sutton Coldfield, West Midlands

Re: Non charging issues

Post by stinkywheels »

Evening Alan

Just put the new rectifier straight on. Your rectifier - every diode forward direction measured exactly the same ohmic reading. The original -all 3 diodes measured different with one being particularly lower than the rest. It may act as a spare if a need one. Not sure if there are any manufacturing tolerances at play here or just after 40 years service it should be expected that they are going to measure different.

This weekend if the weather is ok - I have made up a pair of test wires to temporary connect to the battery and to my test meter. My plan is to fix my voltmeter to the handle bar/clock area and take the bike out for a ride and verify what the regulator is doing at a steady 3000 - 6000 rpm engine speeds. I will tweak the VR at the side of the road if need be. I live in a quite road and the neighbours and the wife are a bit tricky when coming to engine testing on the drive!

Cheers
Paul
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Alan H
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Re: Non charging issues

Post by Alan H »

I looked at repairing the original rectifiers, but at about a tenner a diode (x6!) plus a lot of faffing about and a risk of knackering individual diodes with soldering them into the original fins, against a 3 phase diode set at about a fiver, and rated at 50 amps when the best genny only gives 25 amps........ I didn't think there would be much interest, so chalked 'sod' on that idea, and golox to the purists.
I have all the bits to build test units or plug in rectifiers like the one that Mizzy used, I suppose I should really get on with it...... Someday.......
I have a usb port on the Hippo with a voltmeter built into it as I showed you - very handy to keep an eye on the battery charging (or not). Not expensive either - ebay 114228507871 or similar. Get the red or orange, it's brighter so you can actually see it at a glance.
If the bike is running, point the exhausts into the garage and use the tickover screw on the carb linkage to set the engine speed and it's easier than trying to do it all with the multimeter taped to one of the mirrors at 50 mph!!!
Proof that four strokes are over complicated
stinkywheels
Posts: 26
Joined: Thu May 02, 2013 9:25 pm
Location: Sutton Coldfield, West Midlands

Re: Non charging issues

Post by stinkywheels »

Morning Alan
Tried the idea of pointing the exhausts in the garage - sorted out the bike at the time but the whiff of two stroke Eau de Cologne which had strangely permeated upstairs into the bedroom and stuck around for a week sort of had an adverse effect on my Conjugal Rights. Hmm lessons learnt!

Just want to ensure I am not charging over 14.2v.

As you say the replacement rectifier you provide do work, relatively cheap as chips and dead easy to fit. No brainer.

I am going to order a small volt meter fix to my TDM.

Thanks again
Paul
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