Magneto/Rotor Assembly Question

[dash]

Been going through electrical components on 92 FZR600 Re-Build, and (after finding the main relay needs replacement) fired the engine for first time yesterday. Noticed that battery was boiling and check voltage at an unknown RPM (because the tach was not functioning) until the voltage stabilized at 17.8 volts [Spec 14.3 to 15.3 @ 3k]. Checked the stator resistance and found that both wires were approx 0.8 to 0.9 ohms [Spec 0.31 to 0.38 ohms] at the connector as well as at the stator coil assembly. So probably needs a stator coil assembly, but noticed that inside the magneto rotor the thin plated material that lines the rotor had a place that had worn through at exposed the casting.

Any thoughts as to this relating to the voltage and/or magneto functionality?

[DonTZ125]

A bad stator generally means under charging, not a boiling battery. Similarly, a damaged rotor should reduce the power generated. I'm not sure what this lining is you're referring to. Big point - your VRR is toast, and is allowing a dangerous system voltage. Park the bike until this is fixed, or you'll ruin more expensive parts.

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I had clued in on the Rectifier, but thought that i would check the stator resistance per the service manual. Should there be concern that the resistance is high? The magneto rotor is a cast part that is plated on the interior with approx 20-22 ga steel. The exterior magnets of the stator have "brushed" against the plating and started to wear a hole.

Is there a check for the rectifier other than "last line of defense" in the service manual?

Thank you.

P.S. - Reinstalled the old stator and pulled the VRR...found that the VRR has suffered a small "stab" wound and was oozing slimy substance. The existing VRR has been replaced with a used oem, and if the stab wound occurred after reinstall and before engine was ran, then is it possible to re-seal the old VRR? (NOTE: Engine was not running when i aquired the bike.) Was the reason the voltage was too high because the VRR was not sealed?

I've sealed the VRR with some glue, I'll refire the engine momentarily and re-check voltage. I understand the ramifications of running the voltage up.

[DonTZ125]

The potting in the VRR is drooling because the VRR is running hot because internal components have failed irrepairably. It is ruined, pitch it. Get a new 5-pin VRR, new off eBay for < $50. Get my 4-pin to 5-pin VRR adaptor for $35 shipped, save you a ton of effort. Inspect the connector (outside) and soldering (inside the cover) on the stator for burns or corrosion; the windings rarely increase in resistance, but damage to the connections to the outside world will easily do so, and will cause heat buildup that WILL damage the windings.

[dash]

I wonder if it might be more cost effective to just replace the failed components and weld up a larger heat sink? Budget is always a concern. The "just throw money at it" never works for me. I'll dig into that potting compound and check it out. I'm sure it's a simple 4 diode rectifier board, but you never know?

[DonTZ125]

Since the alternator is 3-phase, the rectifier will be 6 diodes, or more correctly 3 diodes and 3 SCRs. Also, the 4-wire VRR is known to be an issue, and repairing it is false economy when it can fail again and destroy your TCI, your tach, your bulbs, and set your wiring harness on fire.

Seriously, replace it with a 5-wire. I'm not angling for a sale for my own harness; if you don't buy it, I won't be insulted. I just don't want to see a guy wasting his time doing something that may very quickly lead to even more damage to his bike.

[dash]

Thanks. I agree. In the 5 wire VRR, did Yamaha just spread the voltage across an extra wire to reduce the heat generated?

I am most interested as I've been studying with great investigation the inner workings of the electrical system. Since (as you know), I now have a failed main relay assembly, flasher assembly, VRR, and main fuse socket (previous mess). From a wiring loom standpoint, that is all the components on the left tail of the harness and has lead me to consider a winter design project utilizing updated wire connections and components where applicable.

The project is three-fold: 1) restoration on a budget, 2) experience in electrical engineering, and 3) delving into the high performance side of these class of engines.

Though it seems that the third parameter is down the road, it has been a goal for a few years since my back can't stand slinging around those old iron-block chevrolets...aluminium has its merits!

[DonTZ125]

The 4-pin and 5-pin are fundamentally the same; I would expect there is a more robust design internally in the upgraded VRR, but the major upgrade is the addition of a dedicated ground pin. A bad ground path will kill a shunt-style regulator FAST, and the 4-pin design grounds through the VRR housing to the frame of the bike, There is a ground wire bolted to the VRR housing, but any damage or corrosion to that bolt and ring terminal leads to a bad ground.

It sounds like you've taken severe damage to your electrical system due to this fried regulator. Investigate carefully, replace or repair as required.

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When inspecting the bike initially, the wire connections to the VRR all checked (continuity). However, most of the damage to the relays were internal corrosion. The relays had been tampered with (i.e. screwdriver prying into the enclosure) and i am led to believe that the corrosion could have been caused by breaking into the relays? The VRR is not original and was replaced along with the cdi. The cdi is functioning as far as i can tell. After rigging the fuel pump relay, there is a 5 second switching lead coming from the ignition unit upon power from the run switch. My concern now is that tach may or may not be functioning?

When the bike started, it fluttered minimally at 0 rpm seeming like a polarity problem but i have not looked into it yet. I have not found a resistance check for the tach wire leaving the cdi. I'm assuming that since it is the same connection going to the coils that it is only a "fire" signal dictated from the cdi?

Thanks for the info on the 5 pin VRR.

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I'm most concerned that since their is contact with the stator and rotor assembly there is an obvious short occurring within the electrical system. I cant be certain, but it looks like there may be some "arc"ing into the carbs when starting. I checked it yesterday, and read 0 volts (knowing that wasn't right), i rigged some test lines to the multimeter, but now the bike won't start at all? Smells like too much fuel.

I am beginning to think that the rotor might need to be replaced and check for clearance to the stator, but if there is contact then i am led to beleive that the crank may be bent? The bolt that secures the rotor looks clean and does not appear that it has been removed.

[DonTZ125]

The TCI box (not CDI - very different) controls the fuel pump, and sends a 5-sec priming signal on power up, so that much is correct. Some of the tachs use coil flyback; I *suspect* but haven't been able to confirm that the '90+ 600s and 1ks use a square 12v signal. The tach could be damaged from the electrical excursions your bike has experienced.

If you suspect contact between the stator and rotor, definitely have the rotor and bare shaft checked for runout.

Arcing to something carrying fuel - eek!!

[dash]

The taqh is not high priority, but i am definitely concerned about the run out on the crankshaft.

re: "arc"ing...yes houston, we had fire today.