GT500 no spark - possible kill switch issue...???

[MalkyB]

Hi guys - so, my non-running ex Ebay GT500 is still a non-runner. The coils were dead so I replaced those thinking 'Ah - that'll fix it....' No it didn't so whilst I was at it the CDI unit was looking decidedly ropy and covered in 2 stroke oil I thought I'd replace that as well.
Still no spark so I figured it must be the exciter coil on the flywheel - No.
Having got advice this time before spending money I was told 'It must be the pulser / pickup coil....' well it wasn't that either as I still have no spark.
Could it be I have a dodgy kill switch that's stopping the spark....if so how can I test it...???
Any ideas before bankruptcy hits...???

[Zunspec4]

Hi MalkyB,

The kill switch just grounds out the PEI to stop ignition. Just disconnect the kill switch from the loom and try again.



Cheers Geoff

[MalkyB]

Oh it were that simple Geoff!
Further info - the kill switch I've found is working just fine. The kill switch is a link off the supply to the CDI box of tricks which, when it's grounded by flipping the switch, dumps the feed to the CDI through the bars,,,,,How do I know that??? - I got sparks at the bars after I put a direct feed to the box of tricks and flipped the switch! The sparks were from me having loosened the right bar switch allowing the arcing.
I also found while I was rottling around inside the headlight shell the ignition switch wasn't working properly. After a long period of self discovery learning there has to be a feed from the key to the CDI which there wasn't - duff connection,
AHA!!! Thought I - I've jolly well fixed it.
I hadn't - still no spark even after I ran a feed from the battery to the CDI unit.
So I've ordered a new ignition switch but still don't think that's cracked it.
Any ideas anyone...???

[karl pa]

The first thing I would check is the resistance of the magneto where it plugs into cdi, you should have 185 ohms between gr and b/w wire, you should have 214 ohms between b/r and b/w wires, this should show if you have a broken or grounded wire.

[MalkyB]

Done that - all check out

[karl pa]

Then I would unplug the B/Y wire from the cdi and try. the ignition system is free standing from the rest of the electrical system, so you can eliminate everything else from interfering.

[MalkyB]

I'm sorry I don't understand. I can easily cut the black / yellow wire but then what do I test...??

[MalkyB]

I've ordered a new ignition switch (for a X7 but was the only one I could find with 4 wires to the plug and 2 brown feeds for the parking lights) so that should sort out the lack of power to the CDI but......still why no spark now there's power to the CDI box..??? The coils (including HT cables plus & caps), pulsar oil, source coils, CDI and reg/rectifier are all new so all new wires. There's continuity from the CDI to the coils and with power (via a separate test feed) to the CDI now a fluctuating current to the coils.....everything but a spark!!!!!!!!!!!!!!!!!!!

This isn't likely to be something even sillier like no earth from the cylinder head when I hold the plug against it is it...???

[karl pa]

The magneto supplies power to the cdi,you should not have 12 volt power to it.
The black and yellow wire should unplug from the cdi don't need to cut.this wire goes to the switch and kill switch to ground out the cdi.unplug and
kick over

[jabcb]

Disconnect the kill switch & ignition switch. Then test to see if you get a spark.

[MalkyB]

No ignition, no black / yellow to CDI - no spark

Is the rotor likely to be duff....??? I've replaced everything else so running out of options. Would the magnets be failing so insuffient output to fire a spark??? I'd have thought I would have got some faint glimmer of a spark at least.

[Zunspec4]

Hi MalkyB,

Hmm, a conundrum and no mistake. The GT500 ign. is self generating in the same way as the ancient points operated magneto's fitted to many small bikes. The Pulser replaces the points to trigger the PEI, which gets it's power from the ign coil under the rotor. The PEI is totally separate to the charging coils and the rest of the electrical system. It should not be getting 12v from anywhere. I just re-read your post about applying a direct feed to the PEI and getting sparks. I think it's was very likely you were grounding the 12v directly to earth via the kill switch when you did this. Hopefully the PEI was not damaged.

Cheers Geoff

[MalkyB]

Hi Geoff, sadly I won’t know if the CDI is damaged as I still won’t be getting a spark any time soon...!

Can I ask why the kill switch wire goes to the ignition??? Is that to ground the system when you turn off the key rather than turn on power as I’d thought???

I could ask why these systems aren’t made idiot-proof but I guess I wasn’t available when Mr Suzuki was looking for one

[karl pa]

If you unplug the cdi, use a volt meter set to ac volts, check the wires coming from magneto, black and white to green wire, black and white to black and red wire, while kicking over you should get voltage, I am not sure what voltage you should get, but you will know if the magneto is putting out. I wouldn't think the magnets in the flywheel are the issue, but who knows.

[MalkyB]

That's what I'm thinking about the magnets too. When I first got the bike it had a clump on the left side and I'd heard magnets can do all sorts of weird things when clumped!
Many thanks for your help - on to the rotor...and beyond!!!!