13volts at the coils start bike then I have 11volt

been having trouble with this bike for some time
heres whats been done and symptoms

idles good but under load it feels like the spark is week ,feels like a twin

1976 Z1 brand new Z1 enterprises wiring harness
handle bar switches
coils caps plugs
kimpex ignition switch
81 kz1000j igniter and ignition pick ups
new battery
turn power on and bike has 12.8 at the battery(disconnect head light)12.8 at the Y lead that powers the coils
and 12.8 at the coils them selves

now start the bike (again with head light disconnected)and it idles to 13.5 at the battery ,13.5 at the Y connector that feeds the coil
but at the coils I get a 11.2 reading...this only happens while the bike is running????

Ive also swapped batteries,igniters,stators,rectifiers,starter relays,dyna coils,ignition plates
If anyone has a logical answer fire away Im listening
all grounds are clean and secured,the only thing not changed is the kimpex keyed ignition switch
and the new Z1 enterprises handle bar switches

richard wrote: . . . 1976 Z1 . . . 81 kz1000j igniter and ignition pick ups . . . start the bike (again with head light disconnected)and it idles to 13.5 at the battery ,13.5 at the Y connector that feeds the coil
but at the coils I get a 11.2 reading...this only happens while the bike is running???? . . . .

13.5 at the Y connector that feeds the coil but at the coils I get a 11.2 reading -- could this statement be clarified?
As written, it sounds as if there's a voltage drop in the short section of wire between the dual connector and each coil primary terminal.

Also, what ignition coils are fitted?
The igniter system requires a lower resistance coil than the coil used with the stock points system.
Using a too high resistance coil usually results in weaker spark.

Good Fortune!

I am using the stock replacement coils offered by Z1 enterprises
I had DYNAs that did the same and stock ones from my other bike that also did the same
Im not using points.Im using a stock kz1000J plate and pick ups
and yes at the Y Im getting 13.5(idling) but at the coils themselves I get 11.2 ????
I know this seems odd but its happening
I had points before and a dyna plate also with the same results but the dyna plate sucked more power

richard wrote: I am using the stock replacement coils offered by Z1 enterprises
I had DYNAs that did the same and stock ones from my other bike that also did the same
Im not using points.Im using a stock kz1000J plate and pick ups
and yes at the Y Im getting 13.5(idling) but at the coils themselves I get 11.2 ????
I know this seems odd but its happening
I had points before and a dyna plate also with the same results but the dyna plate sucked more power

Stock replacement coils for which bike -- KZ900 or kz1000J?

What is the resistance in the coils now fitted?
(Will require an ohm check of the primary windings),

The green Dyna 3-ohm coils are overly resistant for the igniter ignition which is designed for coils with less than 3 ohms resistance.

Likewise, the stock KZ900 3-4 ohm coils are overly resistant for the igniter ignition which is designed for coils with less than 3 ohms resistance.

Besides achieving the proper coil resistance, should also assure there being no more than ONE resistance component in the secondary loop.
The secondary loop resistance components are:
• Plug wires (solid core copper has no resistance);
• Caps (some have resistance -- others don't);
• Plugs (assure not using "R" plugs.)

In order to maximize spark power, many owners run with zero resistance in the secondary loop, the only downside being RF (radio reception) interference.

Good Fortune!

richard wrote: . . . getting 13.5(idling) but at the coils themselves I get 11.2 ? . . . .

At 4000 rpm, what are readings at battery?

At 4000 rpm, what are readings at each coil?

Good Fortune!

At 4000 the battery is about 15.5 volts
the coils show about 12.5
off gas at idle back to 11,.2

once again this is the 3rd set of coils each one different
the ones Im using are made for the 73 Z1 (new) no ballast resistor
been working on ZEDS and GS for over 20 years never seen this before
Im using an ace well tack it reads only about 75% of the rpms that it actually is
it use to work fine ,I put it on my GS1100 last light and it reads 100 %
put if back on the Z1 and it reads about 75% and flashes like the rpms are cutting out
battery swap makes no difference ,all connections tight with diaelectric grease

richard wrote: . . . coils . . . Im using are made for the 73 Z1 (new) . . . .

Resistance of original Z1 coil is higher than resistance of coils used with the later igniter type ignition system. And the original Z1 coil would be expected to produce a less powerful spark when used with the later igniter type ignition.

Weakness of spark is exacerbated by having optional components in the secondary loop with resistance (such as resistor style plug wires; resistor style plug caps; R type resistor spark plugs).

What type plug wires?
What type plug caps?
What type spark plugs?

Good Fortune!

Am thinking the KZ1000J model with igniter style ignition was fitted at the factory with 2.4Ω ignition coils. (Which is of course lower resistance than the earlier stock Z1's 3-4Ω coils.)

Has spark quality been observed with plugs removed while spinning over the engine?

Good Fortune!

plugs are always pretty clean ,wires caps come with the coils offered by Z1
plugs are non resistor ,used both no difference

all the above mods can be done without issues
this is completely different,the drop in voltage at the coils while running is with every combination Ive stated above

doesnt matter how high the voltage goes during reving the bike ,the coils always read about 2 volts less than the wires feeding them,
If I find out why ,im sure the bike will run fine


I

richard wrote: At 4000 the battery is about 15.5 volts

Regulator is not regulating. Should not be that high.

richard wrote: doesnt matter how high the voltage goes during reving the bike ,the coils always read about 2 volts less than the wires feeding them,

Not sure what that means. If you have a wiring diagram, just take your voltmeter and walk down from the battery, through the ignition switch, fuse, each harness connector to get to the coils and see where the voltage drops are. Be sure to check across the fuses and fuse box connectors as those are notorious for getting resistive with age. Voltage drop means some connection(s) are not 100%.

As stated above its a brand new wiring harness with 13 volts to the coil with the power on
start the bike and the wire leading to the coil is 13.5 idling ,slip the voltage gauge rite at the coil connection tab
and the reading is 11.2...why the huge drop...

as for voltage regulator ive had a crap load of them and Ive never seen one that doesnt reach 15 16 17 volts above 4000rpm
I know that will eat batteries but thats just the way they are made from the factory
if yours taps out at 14volts you got a good one
not to get side tracked thats not the problem