1976 gt550 short/fuse blowing

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slosher
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Re: 1976 gt550 short/fuse blowing

Post by slosher »

Next thing to check then Richie if your not getting any charge is the alternator/generator ;) it really does sound you have some very old and angry gremlins in the system matey

Does the battery hold it's 12.2 charge :?
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rderrick121
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Re: 1976 gt550 short/fuse blowing

Post by rderrick121 »

Hi Dave,

How do I check the generator?

Thanks,

Richie
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slosher
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Re: 1976 gt550 short/fuse blowing

Post by slosher »

Generally when the motor is at idle lights, neutral light etc will show an increase in brightness when the revs are increased to 3000rpm at idle it's just drawing off your battery.Or multimeter across battery terminals.
What mileage is on the bike :?: maybe just the alternator brushes need replacement.
It still sounds to me that something is drawing off the juice somewhere though :?
Looking at your volt regulator have you put the red paint marks on :?: if not that looks like factory set up marks,assuming the blade has not been moved try to realign the red paint marks on the screw adjuster sounds a bit crude i know but iv'e seen similar paint dabs on various parts on my GT's.

Thanks Dave
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Alan H
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Re: 1976 gt550 short/fuse blowing

Post by Alan H »

Plenty of info on here if you do a search for 'charging' or 'alternator'. It'll save having to type it all in again!!

Link here - search.php?keywords=Alternator&terms=al ... mit=Search
Proof that four strokes are over complicated
rderrick121
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Re: 1976 gt550 short/fuse blowing

Post by rderrick121 »

Hi Slosher and Alan, is it possible my voltage regulator is just bad any tests I can do on the reg? I know that a problem with age and this is likely to be original. I think the mileage is about 13k.

Thank you,

Richie.
asco58
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Re: 1976 gt550 short/fuse blowing

Post by asco58 »

Hi, You can have a look at the GT550 shop manual on the OJB site https://www.oldjapanesebikes.com/mraxl_ ... /index.php
and click on the the link that says "Engine Electrical".

If you go through the pages, Suzuki have outlined how to test the rotor, alternator, rectifier and voltage regulator. They've also got a circuit diagram as well. The manual has information for both the Denso and Kokusan electrical equipment. You might want to double check the brand of your alternator as well before you start.

The voltage regulators on these bikes are relatively simple electromechanical devices. The points in the regulator are supposed to switch to the high resistance circuit around 3000 rpm or so and reduce the field coil's current and reduce the voltage that way. The screw needs to be wound in enough to tension the relay so that it doesn't switch at a low rpm otherwise it won't charge. Adjusting the regulator is also covered in the shop manual. Hope this is of some help and that you fix your electrical gremlins.
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slosher
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Re: 1976 gt550 short/fuse blowing

Post by slosher »

That's a great find asco58 very informative :) and god bless Ian Sandy for publishing it
It's all in that link Richie ;)

Cheers Dave
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canaletto5
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Re: 1976 gt550 short/fuse blowing

Post by canaletto5 »

asco58 wrote: Thu Apr 08, 2021 8:21 pm Hi, You can have a look at the GT550 shop manual on the OJB site https://www.oldjapanesebikes.com/mraxl_ ... /index.php
and click on the the link that says "Engine Electrical".

If you go through the pages, Suzuki have outlined how to test the rotor, alternator, rectifier and voltage regulator. They've also got a circuit diagram as well. The manual has information for both the Denso and Kokusan electrical equipment. You might want to double check the brand of your alternator as well before you start.

The voltage regulators on these bikes are relatively simple electromechanical devices. The points in the regulator are supposed to switch to the high resistance circuit around 3000 rpm or so and reduce the field coil's current and reduce the voltage that way. The screw needs to be wound in enough to tension the relay so that it doesn't switch at a low rpm otherwise it won't charge. Adjusting the regulator is also covered in the shop manual. Hope this is of some help and that you fix your electrical gremlins.
Excellent bit of research
asco58
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Re: 1976 gt550 short/fuse blowing

Post by asco58 »

canaletto5 wrote: Thu Apr 08, 2021 11:05 pm Excellent bit of research
I actually had to look into all my electronics not too long ago after my battery wasn't charging, fuses kept blowing and the brittle connectors were melting or cracking. Someone had moved my regulator arm in the wrong direction by a lot so that when the ignition was switched on, the battery voltage alone caused the regulator to switch to the high resistance circuit without the engine running. Gave me the illusion it wasn't working. Someone had also chopped off some of the original connectors and connected individual wires with those twist on cap connectors :shock: . Long story short, After spending ages tracing faults, I made myself a new wiring loom which seems to have fixed everything. It sounds like a cop out but sometimes it's just easier to replace very old bad wiring instead of trying to fix it :) . Ash
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canaletto5
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Re: 1976 gt550 short/fuse blowing

Post by canaletto5 »

Undoing 45 years of bodge is a skill in it's own right :lol:
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