1993 gsxr 750 wp no spark

[symona1]

Hi all, hopefully get some help with this.

Bought the above bike last Sunday with no power at all to ignition, thought I'd take a chance. Got her home, charged the battery overnight and put it back on in the morning showing 12.9v, turned the key and still no life.

No ignition lights whatsoever, so stripped her down, removed the seats, tank and fairings and set about with a multimeter and wiring diagram. Everything checked out, continuity on every wire I checked along with clutch lever switch, side stand switch and neutral switch, all fuses are good too

Went back to basics and started to trace everything from the battery onwards again, on further inspection the starter solenoid was hooked up the wrong way i.e the positive lead from the battery was going to the M terminal ( motor side ) and the Starter motor lead was hooked up to the B ( battery ) terminal, so there was the reason for no power.

Switched them around, turned the key and I was greeted by the neutral light and oil light. Pressed the starter button and she spun over, great but no spark on any plug, set my multimeter to volts and probed the o/w wire to my coils and grounded to the battery negative, both showed a little over 12v with ignition on that dropped to around 9v while hitting the start button.

All plugs have been grounded against the frame while turning the bike over and no spark, I removed the coils and tested them for ohms across the terminals which came back at 4.5ohms for both on the primary side and 15k ohms on the secondary side through the plug caps.

Tested the white wire on the rear coil and b/y on the front coil for continuity to the ignitor and they both check out, signal generator is giving 172ohms on the green and black wires on the connector under the seat. Does this model have the resistor on the ignition to drop the voltage to 8v going to the ignitor ( CDI ) box ?

Loosing the will with this now, sorry for the long long post I just wanted to make sure I put as much info on as possible.

Very grateful for any and all help.

Edited May 31 by symona1
Grammar

[Digs]

I’d place money it’s the resistor on the ignition barrel. It’s an anti-theft feature.
 

Check the resistance between the (if I remember rightly) orange and red on the barrel. 

[symona1]

Cheers for the reply, is there actually one on these as I thought it was on the later srad models ? I know there's a 3 pin diode up by the battery on the left as you're sitting on the bike.

I will check the orange/red though thanks.

[symona1]

Okay, went out this morning and disconnected the ignition switch at the green block. Set my meter to 200 ohms and probed the red ingnition wire with my positive and negative to the orange wire.

Turned on the key and I get a fluctuating reading that can go anywhere from 2.8 ohms up to over 50 ohms as i move the wires beneath the ignition barrel.

[symona1]

Just for anyone who may be following this, no diode in the ignition as I took it into work to strip out the security bolts and strip it down.

Changed the coils for good known working second hand originals and still no spark.

Surely it now has to be the ignitor/CDI.

[Gixer1460]

On 6/1/2024 at 5:44 PM, symona1 said:

 I know there's a 3 pin diode up by the battery on the left as you're sitting on the bike.

That thing is a PITA and really only there as interlock safety feature for side stand / clutch / in gear / starting. It got binned from mine!

On 6/2/2024 at 1:24 PM, symona1 said:

Okay, went out this morning and disconnected the ignition switch at the green block. Set my meter to 200 ohms and probed the red ingnition wire with my positive and negative to the orange wire. Turned on the key and I get a fluctuating reading that can go anywhere from 2.8 ohms up to over 50 ohms as i move the wires beneath the ignition barrel.

That sound more like a dodgy / broken wire in the loom making intermittent / high resistance connection! Not unheard of due to all the twisting it does!

3 hours ago, symona1 said:

Just for anyone who may be following this, no diode in the ignition as I took it into work to strip out the security bolts and strip it down.

Changed the coils for good known working second hand originals and still no spark.

Surely it now has to be the ignitor/CDI.

I thought it was only the Blandits that had a 100ohm RESISTOR in the Ign. Switch - I could be wrong though!

[symona1]

As stated earlier it didn't have one, but as I was stripping the ignition down to check for a broken wire inside due to the ohms rising and falling when moved I looked anyway and as I suspected it doesn't have one.

So thoughts now are as stated earlier the ignitor/cdi

[Dezza]

My mate's 750W definitely had a resistor in the ignition switch. After a rebuild it would't start because the solder in the switch had broken. Once reconnected it ran fine.

[symona1]

100% not one in mine, had it apart this morning and all 4 wires, red, orange, brown and grey are soldered straight to the disc. 

[Dezza]

Maybe it has one hidden in the loom, and that's failed or become disconnected.

[symona1]

Possibly, however all cables test fine for continuity end to and and when a diode goes down they don't let anything through so would show as no continuity on that wire.