Help Electrical Questions

Amperage capacity for one. FH020AA is good for 35 amps, SH847 is good for 50 amps. So depending on stator output, accessories requiring extra juice will either put a strain on the regulator as it struggles to keep up with the draw taken from running the bike plus accessories and recharging the battery, or it will eat it up no problem and ask for more.

In the current crop of regulators, FH is a MOSFET shunt type, and SH is a series (non-shunt) type, the SH821 should be a good regulator. Not sure if it would be rated for 50 amps like the SH847 though. It's hard to find specific details from Shindengen, but here is their page for motorcycle stuff:

https://www.shindengen.com/products/electro/motorcycle/reg/

I once worked on a Kawasaki Vulcan Classic (VN1700G) - that thing had two stators and two regulators. The only reason I can imagine that would be needed is for when a metric crapload of accessories bolted to it. Radio, GPS, speakers, satellite phone, heated seats, beverage warmer, refridgerator

 

Remember that shunt-circuit RR needs sufficient capacity to handle 100% of stator's output. The less bike's electronics uses, the more is dumped to ground and actually generates more heat.



Sum of 4 & 5 is always equal to stator max output. The less bike's electronics uses, more is dumped to ground and wasted. Rather than heat being dissipated by headlights & clocks where power is used, that extra heat will be concentrated at RR now.

You can lower parasitic power-loss by installing smaller stator along with series-circuit RR that only passes sufficient current for bike's demands. Frees up bhp not driving stator at 100%. RR runs so cool, you can touch it after ride. I actually put my SH775 RR underneath battery on VFR as spacer since lithium battery is so much smaller than stock.

https://www.lazmonsta-racing.com/RG-YAMFZR400-98-02

 

A lot of times on old bikes, the standard wiring has resistances or bad joins leading to voltage loss, particularly affecting the charging circuit. That's the reason for sending the positive/negative leads straight to the battery from the regulator. The charging circuit will be particularly sensitive to any high resistance and generate excessive heat either at the regulator or the plugs for the stator/regulator, hence burnt and melted plugs. Sometimes the connectors themselves are the problem, I've seen many of those female spade terminals with a loose fit after years of being disconnected, reconnected, and heat cycled (the curls open up and no longer provide a good connection). Or just straight up corrosion/rust, in which case it's best to just chop and re-pin with new connectors.

When you bypass the main harness and go direct to battery for the charging circuit you will generally see a large improvement on an old bike.

On the ZXR250 I had to tap in to one of the 3 phase leads to power the headlight relay after going direct to battery with the charging system as there was a 6th wire on the reg/rec that controlled the headlight turning on or off.

FZR250 and 400 look to have only 2-phase stators. 2 white wires from the stator plus positive to the harness/battery, and earth through the body. So in that case you just hook up your 2 phase to the rectifier side and leave one of the pins blank, and then positive/earth straight to battery.

Mounting the regulator somewhere with airflow of course. Most new bikes either have them under the tail with the fins exposed, or mounted behind the rear shock, and sometimes in the front fairing with a cutout to expose the fins, or mounted on the lower triple tree.

 

I knew I'd read something of this nature way back in the long dark past when Dinosaurs still roamed the earth - 2005 GSX-R1000 stator adapted to the VFR400 - check the weight comparison

https://mngforce.typepad.com/nc450vdev/part-evolution-generator.html

 

If you cut back the flywheel and as a consequence cut back the magnets you will reduce the magnet field available to the alternator. this will effectively reduce the alternator output (power). Not really an issue on a race bike, but might be an issue if you still need to power the kickass stereo, multimedia system, spot lights, etc.

 

I think I've seen THAT bike, it was the two wheeled equivalent of a Winnebago

 

Hi Frank,
Are these coils actually original ones. Are you sure they are not from another model.
A lower coil resistance will theoretically result in less primary current. The fact that both are similar values leads me to believe that they were probably made with that value out of the factory. I would be suspicious about them both having drifting characteristics over time at the same rate.
The only time I have had to throw a coil out is when it has just gone open or short on one of the windings or the insulation resistance between primary and secondary is out of spec (tested with an insulation tester).
I would be inclined to try them and see what happens. If they break down under load/high revs, then maybe some new coils might be the go.

 

Sorry guys. A lapse of concentration. Lower resistance means HIGHER current. But, of course, the TCI needs to be up to the job.
Interestingly the coils on an MC17 - MC22 have primary resistance in the range of 2.0 - 3.5 ohm.
Frank are you adjusting for the lead resistance in your measurements? This could easily be a few 10ths of an ohm. also try a second meter. Standard, lower cost multimeters are not that good at the lower end of their ranges.


Peter.