Alternator Problems

[smegballs]

My mates 1991 GS400E (Jap import model) apparently has permanent magnets in the alternator instead of field windings and brushes etc etc...

The charging voltage is almost non-existent at idle and only gets to the high 12's to mid 13 volts at high revs.

As magnets dont stay magnets forever, is it implausible that as the magnets are subjected to age, vibes, heating and cooling etc etc over the years the magnets lose their potentcy or is it more like to be a reg/rec fault.

Bike is basically the same as a GS500E apart from barrels and pistons so 500 owners please chime in.

Also does the GS400/500 have a low speed mixture screw or is it all done on the needle and the main jet??

Cheers, Rich

[stinkwheel]

Permanant magnets are permanent. As the name suggests. They are made of magnetite, not magnetised bits of metal.

Reg recs usually either work or don't work. Not often an inbetween state.

Metal oxides are poor conductors of electricity. First step would be to make sure all the connectors between the alternator and the battery are clean, connected properly and corrosion free.

Batteries do not last forever. I'd suggest replacing the battery as a next step.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Alabama Blacksnake]

Tis a brand new battery on the bike. Thats why we are a bit confused as to why it wont crank after a good run.

Dont help lights are permanently on as the batt tries to crank but we're working on that.

Rich
____________________
Bikes i've owned: mobylette ----- Ts 50er ------ GS 400e ------ CB250n superdream ------r6 ------ bandit 400 ----- 2005 kx 125
Bikes i have:dtr125 field bike that doesnt not seem to die!!! 1992 gsxr 750
trevoriv said: Leathers are like teenage girls, the tighter the better.

[stinkwheel]

May be worth checking the windings are all intact.

I'm guessing here that there are three yellow wires that attach to the reg/rec unit. There should be a lowish and equal resistance (indicating the presence of a coil, say a few kilo ohms) when you measure between each pair of yellow wires. There should be an open circuit when you measure between any yellow wire and earth.

If you can get the engine running with the reg/rec disconnected, you should get somewhere in the region of 30v A.C between any pair of yellow wires. Be careful not to zap yourself.

Anything different, report back.
____________________
“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.