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 Suzuki GN400

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Bene



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PostSubject: Suzuki GN400   Tue Mar 03, 2015 8:41 pm

Hey, I have recently acquired a '81 GN400. Im having issues with the headlamp. I was told by the previous owner he was having trouble with it blowing 6v bulbs at high revs so he had put a 12v bulb in since then (assuming I have a problem with the rectifier) All was fine though for a while then I assumed I must have blown the bulb the other day. Checked the bulb which was fine. Checked to see If there's power to the lamp and found nothing there's also no hi/lo light signal showing.. Have checked the fuse and looked over the visible wiring which all looks ok. Any ideas? Also I have a manual but cant figure out what 'E' series my bike is. If anyone can tell me how to find that out would be much appreciated.
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Irishjon
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PostSubject: Re: Suzuki GN400   Thu Mar 05, 2015 9:45 am

I would be very surprised if an 81 bike was still 6 volt. The hi/lo indicator lights are fed off the same wire that feeds the bulb. Assuming that the fuse isn't blown (I'd still check that with a meter) then there is either a break or a short before the wire gets to the headlight or a dodgy earth somewhere.
If you have a meter, check for power at the back of the bulb. On old Jap bikes it's pretty usual to get a bad connection inside that rat's nest in the headlight shell.

Cheers
Irish

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Bene



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PostSubject: Re: Suzuki GN400   Thu Mar 05, 2015 10:00 am

Thanks Irish. Yeah its a definite rats nest in there... Its definitely 6v too. I tested at the back of the bulb and theres nothing, unplugged the connection point and nothing there either. The fuse (as far is I can find there is only one on the bike?) is good. So you think dodgy wire/earth somewhere?
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PostSubject: Re: Suzuki GN400   Thu Mar 05, 2015 1:27 pm

If there's only one fuse there should be a wire from there running to the hi/lo switch and from there to the bulb. See if you get power coming into the switch. If you are, it's probably easier to cut a new wire into the output from the switch and connect that to the one going into the bulb. If you aren't getting at the switch you could cut into the output from the fuse and run a new wire to the switch. It might be easier than taking the whole loom apart to find a break in the original wiring.

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scotty
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PostSubject: Re: Suzuki GN400   Thu Mar 05, 2015 6:23 pm

try what irish suggested run a wire direct from battery to lighting switch and that will check if the switch and bulb are all good.
I think on the 6volt GN you will find the lights run off a separate ac winding in the magneto so will only go with engine running you may have a faulty winding, there is usually a pink wire coming from the magneto you need to test with multimeter on ac voltage

cheers
scottty
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PostSubject: Re: Suzuki GN400   Sat Mar 07, 2015 4:19 pm

Cheers guys. As I was unaware it was AC running straight from the magneto I of course wasn't getting a reading on my meter set at DC. The cause of the bulb not running was the earth connection inside the bulb mount, quick solder and its good to go. The question I have now is why at the bulb is it getting spikes as high as 17v at higher revs? Ive got a 12v bulb in it and its ok but sure that cant be right... Does that suggest the windings buggered?
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PostSubject: Re: Suzuki GN400   Sat Mar 07, 2015 7:15 pm

I'll leave that to Scotty. My knowledge ended at the dodgy earth rabbit

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PostSubject: Re: Suzuki GN400   Sun Mar 08, 2015 9:32 pm

that sounds about right can get up to 20volts ac at 5000rpm it is a pretty crapy electrical system and quite common to blow bulbs,

the GN400's aren't very common in nz I've only worked on one years ago thats how i knew about the ac mag, just make sure the bulb wattage is correct as that load is what regulates the voltage, i think the engine is the same as DR400 so could possibly convert to 12volt magneto if you wanted to spend the money
cheers
scotty
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PostSubject: Re: Suzuki GN400   Today at 7:27 am

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