1981 GS650G TCI\CDI Questions

[Rahmanberrada]

Hi Everyone,
I have a Gs650G that i picked up, in bad shape, and trying to get running and breathing again.
My technician and I are confused as to whether the ignition is TCI or CDI, the manual says Transition and everywhere else online says CDI. We know it's dead and has been tested. Question is, does anyone have an idea fora replacement that doesn't include a $200 Dyna S ignition, I read somewhere that you can use a GM HEI module. If thats true, has anyone done it? And HOW did you do do it?

I really appreciate any input.

Credentials:
Myself: Fairly new to motorcycles, slowly learning
Technician: Mad scientist \ Misdiagnosed Genius. lol

Let's get this baby to purr again, last time it ran and was registered was in 1989......

Cheers

[leftlostcommonsense]

Dyna S can be had on ebay brand new in the box for less than $150 from a certified dealer. ATVGalaxy on ebay has the exact ds3-2 you will need for $112 free shipping and factory warranty. The only thing you will have to do is cut a small half moon in the plate in order to clear the oil pressure switch a grinder with a sanding pad is what I used. It's much better than a hack job trying to use a GM part and does away with the ignitor and pickups all in one go. I've yet to have any issue since installation and made my engine run like new again. I didn't even realize what I had been missing until I installed it lol.

[Steve]

My technician and I are confused as to whether the ignition is TCI or CDI, the manual says Transition and everywhere else online says CDI.

First, let's define the letters:
CDI is Capacitive Discharge ignition
TCI is not found in my manual, but is probably Transistor Controlled Ignition?

My 850 manual calls it FULL-TRANSISTORIZED IGNITION SYSTEM.

I can assure you it is NOT a CDI, because there is no large capacitor that gets charged up, then discharged when demanded by the sensors. The term CDI is commonly (mis-)used because that was a popular aftermarket upgrade to cars back in the day. The feeling was "if its transistorized, it <must> be CDI".

If you must apply letters to the system, it is just a classic IDI, or Inductive Discharge Ignition, where a bunch of steel is magnetized by an electric current. When the current stops, because a set of points opens, the magnetic field collapses , creating a reverse current, which is amplified by another set of wire windings. That device is the coil, commonly used for the last 100 years. The only difference in your bike is that the mechanical points are replaced by a box of transistors. There are no moving parts, nothing to wear or adjust on a regular basis, but they <do> occasionally fail. In Suzuki terms, that box of transistors is known as the "Ignitor".

.

[Charlie G]

I have a used one off an 82-650g I'd be wiling to part with. Shoot me a PM if interested.

[Rahmanberrada]

Dyna S can be had on ebay brand new in the box for less than $150 from a certified dealer. ATVGalaxy on ebay has the exact ds3-2 you will need for $112 free shipping and factory warranty. The only thing you will have to do is cut a small half moon in the plate in order to clear the oil pressure switch a grinder with a sanding pad is what I used. It's much better than a hack job trying to use a GM part and does away with the ignitor and pickups all in one go. I've yet to have any issue since installation and made my engine run like new again. I didn't even realize what I had been missing until I installed it lol.

Thanks for the info guys, in regards to the Dyna DS3-2, the Gs650G isn't part of the bikes they list as compatible. they have the other Gs series. is that because of the slight modification needed to the plate? also, does anyone have a picture of what that cut looks like or how big it is? Thanks

[tom203]

Another guy with a bad 650 ignitor....? Ok, the dyna will fit, cutout looks something like this pic

image.jpg

[leftlostcommonsense]

Thanks for the info guys, in regards to the Dyna DS3-2, the Gs650G isn't part of the bikes they list as compatible. they have the other Gs series. is that because of the slight modification needed to the plate? also, does anyone have a picture of what that cut looks like or how big it is? Thanks

Yeah it's not listed due to needing the plate cutout. It's simple to do though. The ds3-2 is the one you need. May I ask how you know it's the ignitor though? The experts here seem skeptical when someone says their 650 ignitor is out. I thought mine was bad too but it ended up being a break in the output wire of the killswitch underneath the covering that's over the wire so I didn't see it. I'd have 12 volts everywhere including coils when the ignitor was unplugged. If the ignitor was plugged in I only had .5-2v at the coils. A bad connection or break in the wire can make it seem as though everything is working but the load from the ignitor box is just enough to kill the power.

[Rahmanberrada]

Well, the bike hasn't run since 1989, so a lot of the wiring is corroded. We plugged a battery straight to the starter solenoid, the bike cranks but there is no spark, we changed the spark plugs, still nothing. There is voltage all the way to the ignitor but nothing out of it, we tried cleaning the wires and even took it off and connected it to a CDI testing module, thats what gave the negative result. Either way, i am sure i will be happy with a tried and tested solution to my problem. As of now, the parts that i have on order are:
- Battery
- Regulator\Rectifier
- DS3-2 Ignition
- Ignition Coils
- Spark plugs.
I believe that should take care of the spark going into the engine.
Now to get the carbs off and cleaned, rebuilt to spec and get her fired up. Once that's done, we'll get to the frame modifications, etc..

[Steve]

There is voltage all the way to the ignitor but nothing out of it, ...

There is a very good reason that you did not see any voltage coming out of the ignitor. It controls the GROUND side of the coils. While it is running, there will be current coming through the coils while the electronic "points" (transistors) are closed, but since you are at a ground point, there will be zero volts. When the "points" open, there will be voltage for a few milliseconds, then the "points" will close again and voltage will return to zero. Again, that is voltage coming IN to the ignitor from the coil wires, not leaving the ignitor.

... even took it off and connected it to a CDI testing module, thats what gave the negative result.

If the tester is specifically for a CDI, that is normal and expected. Did you read post #3? What you have is not, make that NOT, a CDI unit. They work completely differently and need different testing equipment. A CDI stores the high voltage in a capacitor, then discharges it to the spark plugs, hence the name Capacitive Discharge Ignition. We have no capacitors, we have inductive COILS, the ignitor is just a box of transistors that replaces the mechanical points.

.