No spark

If there is power to the primary of the coils, it means that the electronic
ignition is either disconnected, fried or not triggering (ie: he'd plled a
wire off the pickup somewhere).
The 18V is dodgy though. Could be a knackered regulator. Where and how/with
what was this voltage measured?

JB

 

In that case I reckon the regulator is either fried or disconnected/shorted
out somehow and likely the electronic ignition is also dead as a result. You
may be lucky as most automotive electronic can handle 30VDC with no real
hassle, BUT only short term.
Start from the beginning and chceck all wiring from alternator thorugh to
reg/rec unit first. You can check reg/rec unti off the bike fairly easily
with a variable DC power supply.
If you get stuck, I can check it for you. If the electronic ignition is
bolloxed, you may have a problem finding one for the 400 model.

JB

 

snippety

unless it were a very primitive system.

I think that is _exactly_ what this is. High current NPN or NFETs are
cheaper and more rugged that PNP/PFETs. Pretty usual on electronic ignitions
in the 70s/80s/90s.

JB

 

Good move. Sensible policies etc.....

JB

 

My daughters boyfriends been fucking around with his bike wiring and
no longer has power to the HT leads

There's power too the coils , the battery is new and the bikes
charging at 18 volts so i assume he's fried something

The bikes a jap import GSXR 400 f about 1987

Any ideas

It was running before he messed with it but it was charging at 18
volts

Steve

 

The voltage was measured across the Battery , the multimeters mine
and its calibrated so its reading spot on

 

No spark

The primary side of both coils are recieving power

He decided to rewire the bike and was going to change the voltage
regulator , had the tank and seat off , bits everywhere

 

There isn't an immobilizer is there? Or a kill switch wire that's been
disturbed?

If there's voltage on the coil primaries, measured against what? I'd
guess chassis ground?

Are the coil primaries grounded at the coil (I expect them to be but
you never know); if so then the ignition would use a high-side driver.

Would electronic ignition leave DC flowing through the coils? Sounds
unlikely unless it were a very primitive system.

If the coils primaries' negative ends are connected to the ignition
(i.e 12V into the coil and switched on the -ve side) then that could
explain the voltage on the coils. I doubt this is the case though.

 

Lets get back to a few basics here. There should be a supply to one
LT side of the coils. Imagine for a moment an old system with
points rather than electronics. While the points are closed the
other LT terminal is earthed and a current flows. When the points
open there is a back EMF created in the LT coil which discharges
into the capacitor. This induces a voltage into the HT side creating
your spark.

The electronic ignition gubbins just does exactly the same job as the
points and capacitor, just more reliably.

So .... Check that there is voltage on one LT side of the coil and
earth on the other. Now disconnect the earth side and you should get
a spark. The spark will be weak because there is no capacitor.

Sounds like the battery will have either boiled dry or been damaged
by now. The reg/rec should be limiting the voltage to a tad over
14 volts.

Clearly the lad has screwed up the wiring somehow and probably
damaged the electronics. First get hold of a proper wiring diagram
and trace the wiring, each wire should be colour coded. When you
get this sorted test it all again, you might be lucky or you may
have to replace the rec/rec and/or the ignition module.

If you are not confident with the above get a proper man in.

 

Ah. I didn't realize it was so common.

 

I am only asking the questions i aint getting involved otherwise it
will be stuck in my garage and left for me to fix it

I dont mind offering advice but i work on the basis he fucked it up
he can fix it

 

Thanks i have a variable power supply , im trying only to pass on
advice to him possibly test his components other than that , he
fucked it up he can fix it .

 

I know that theres no immobilizer , he rechecking all his wires
tomorrow

Dont know

The bikes circa 1986