Kawasaki GPZ 900R Alternator what is the operational rev range?

Question

I am trying to run this in a racing car (low power requirements). At 8000 rpm (revs of alternator) the alternator produces 6 volts. With car alternators the gearing is usually around 2 or 3 times engine speed.
To get 12 volts I will have to run at 16000 rpm (alternator) is this normal?
Surely 12 volts should be produced at bike engine tick over?

Answer 1

Pauly,,,
I do Not know the exact specs and details of your enigine's alternator output.

I can tell you in general terms that TYPICALLY it would be
Approximate Range:

About 13.5~14 Volts
About 20~24 Amps
About 5~6,000 rpm PeakCharging Output
About 1500~2000rpm to begin minimum charging output

Yours is WAAAAAAY outa whack.

The "6 Volts" is Suspicious.

That sounds like what you'd get from One Wire of a 3Phase Alternator after being rectfied to DC current.

Or,,1/3 of Full output..


I dont even know for a Fact if your dynamo is Single Phase or 3-Phase.
I'd BET it's 3 Phase,,,that'd be stereotypical

So the Low Output figures You're getting suggests a few problems.

***There should be 3 Charging Wires carrying A/C to
a Rectifier/Regulator Unit
---Wires are Not Connected properly,or damaged
or
---Rectifier has some Diodes that've failed Open and are not carrying current
or
--Certain Coils in the 3-phase Alternator have failed

........................................................................
Best Suggestion :
Get a appropriate Shop Manual,,,

*test each output wire from Engine to Rectifier.
Probably Yellow or White wires,,,there should be 3 of a kind.

They'll be A/C Voltage,,and quite Hi-Voltage(so be Careful)
Check using a A/C voltmeter .

*Use an Ohmmeter to check Rectifier.
Each input pin should show continuity to Output pin in One Direction,,,but NONE in Opposite direction


Alternator Failure is Not Uncommon.
But Rectifier Failure is lots More common.

Sorry I cannot tell you Precisely the wiring color code and detailed specs of the test values.

But it's a very simple system to test,,,,,,,,
and a generic test approach will help you determine What's Functional or Not

Good Luck with it

Answer 2

It should be the normal rev range for the bike. Most motorcycle alternators have low output at idle. The reason for this is the large rpm spead. Car alternators operate within a smaller spread.