1972 Suzuki T500 Spark problem

All to do with wiring, charging or just trying to figure out whats gone wrong.

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Wernvilla
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Suzuki 2-Strokes: 1972 Suzuki T500J
Location: Wales, UK

1972 Suzuki T500 Spark problem

Post by Wernvilla »

Hello,

I know this issue comes up a lot on the forum.

I have an issue.....

Got great spark on Right side
No spark on left

Been checking points multiple times and all is set good.

I checked the voltage with the points open
Right side - 12.4v
Left side - 23.2m v no spark - got little voltage not alot

Would this be down to Regulator fault?

Coils have been tested
Primary - 4.4k
Secondary - 12.5k
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jabcb
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Suzuki 2-Strokes: 69 T350 thru 75 GT750
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Re: 1972 Suzuki T500 Spark problem

Post by jabcb »

Not sure what you have based on your explanation.

Looks for voltage drops that are not good:
With left point closed & right point open, check voltage at both primary sides of both coils.
With left point open & right point closed, check voltage at both primary sides of both coils.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 project & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
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Wernvilla
Still in the Driveway
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Suzuki 2-Strokes: 1972 Suzuki T500J
Location: Wales, UK

Re: 1972 Suzuki T500 Spark problem

Post by Wernvilla »

With left point closed & right point open, check voltage - 0.00v on both
With left point open & right point closed, check voltage - left - 0.00v right 11.3v
Wernvilla
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Suzuki 2-Strokes: 1972 Suzuki T500J
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Re: 1972 Suzuki T500 Spark problem

Post by Wernvilla »

For side with closed points:
coil voltage for orange wire should be close to 12.4v - I got 12.2v
coil voltage for other wire (White) should be close to 0v - I got 12.2v
voltage on coil side of points should be about 0v - I got 0v
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jabcb
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Re: 1972 Suzuki T500 Spark problem

Post by jabcb »

Did you replace the points? Or remove them for cleaning or inspection?
Did you disconnect & reconnect any the the ignition circuit wiring?
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 project & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
Wernvilla
Still in the Driveway
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Joined: Thu May 28, 2020 8:52 am
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Suzuki 2-Strokes: 1972 Suzuki T500J
Location: Wales, UK

Re: 1972 Suzuki T500 Spark problem

Post by Wernvilla »

Fitted new points and condensers

And yes i have had the loom apart
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jabcb
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Re: 1972 Suzuki T500 Spark problem

Post by jabcb »

You probably incorrectly installed the left points. If the insulators & other parts are in the wrong order, you can end up with no current going through the coils, or current always going through the coils.

See:
ImagePointDiagram1 by jabcb, on Flickr
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 project & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
Wernvilla
Still in the Driveway
Posts: 7
Joined: Thu May 28, 2020 8:52 am
Country: Uk
Suzuki 2-Strokes: 1972 Suzuki T500J
Location: Wales, UK

Re: 1972 Suzuki T500 Spark problem

Post by Wernvilla »

I got spark at both sides on the points.

If i manual move points on left side i get a small spark from plug.

Right side is sparking great.

Thats for drawing, thats really helpful and very well drawn
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jabcb
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Joined: Mon Dec 13, 2010 4:32 pm
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Suzuki 2-Strokes: 69 T350 thru 75 GT750
Location: southwestern Pennsylvania

Re: 1972 Suzuki T500 Spark problem

Post by jabcb »

This kind of problem is not easy to diagnose via a forum.

You should not be getting much of a spark at the points. If the spark at the left points appears bigger, you might have a bad condenser.

You could try running a temporary wire from the coils to the right points. If you get a good spark when you test the right coil, and a bad spark when you test the left coil, then the coil is suspect.

You might have a bad plug cap. The resister in the cap can go bad.

Also check & clean the electrical connectors between the coils & points. Make sure they are properly seated.

Make sure to charge up the battery too. The electrical systems on these bikes are marginal. It might be fine with a good fully-charged battery. With a weak battery, these bikes tend to loose spark on one cylinder before the other one.
BAS (Bike Acquisition Syndrome) - too many bikes but have room for more

Suzuki:
GT750 2x75
GT550 72 project & 75
GT380 72
T500 69 project & 73 project
T350 69 & 71
Honda 85 CB650SC & 86 CB700SC
09 Triumph Bonneville SE
alanr
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Re: 1972 Suzuki T500 Spark problem

Post by alanr »

Was it running well before new points put in.
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Wernvilla
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Suzuki 2-Strokes: 1972 Suzuki T500J
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Re: 1972 Suzuki T500 Spark problem

Post by Wernvilla »

Bought bike as a non runner

I finally got spark on both sides

I refitted the original points and now got spark on both.
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