Cheap G1 CDI - $20.16

[kwest0425]

Out of curiosity, I was trying to figure out what was in a G1 Cap Discharge Ignition module that was worth $200-$300. I came to the conclusion.... not much, especially for a 1-cylinder, 2-stroke like the G1. The most unique thing about the G1 engine is that it (like a few others) can run backwards. I decided to try and build my own CDI.

In doing a little more research though, I came across some very inexpensive chinese CDIs for ATVs and dirt bikes. They typically come in two flavors, a 5-pin version which gets its power from the magneto source coil and a 4-pin version which is powered by the 12v system and doesn't require a source coil input.

I ordered a 5-pin CDI and a harness which I figured could be adapted to my needs. WWW.BESTGPG.COM

The pinouts on the 5-pin differ from a 6-pin yamaha oem CDI in that there is only one pulser input on the 5-pin, while the 6-pin yamaha has two, one for forward and one for reverse.

I saw a schematic in the yamaha shop manual which seemed to indicate that the two pulser inputs were simply tied together within the CDI through a couple of diodes, so I duplicated that outside the new CDI on the harness (see attached).

Anyway, the darn thing works and performance wise I can't tell the difference between the two.

Cost to Build

Component/ Supplier/ Cost

CDI and Harness/ bestgpg.com/ $14.99
1N4004 Diodes(2)/ Radio Shack/ 0.99
PC Board/ Radio Shack/ 1.99 - not really required
Snap Connectors/ Radio Shack/ 2.19

Total Cost $20.16

kwest

[roady89]

Sticky worthy. Thanks

[Rosati]

Excellent info, I was wondering if these cheaper versions could be adapted as well,
but my electrical knowledge isn't on the highest level.
I know only the basic stuff, enough to get by most of the time.

[sho305]

If you dig around some of the Chinese motorcycles are yamaha copies but think they are all 4 strokes....if that matters, not sure on the scooters but some are 2 stoke. However you can get adjustable CDI for some of them but they cost more, then you can play with the timing advance curve.

Great post BTW!

[kwest0425]

Yeh, I thought about getting one with adjustable timing but I wasn't sure this was going to work so I went cheap. Interesting experiment though. I wonder what that would do to the 2-stroke performance?

-kwest

[sho305]

It made the one I had go faster, I advanced the plate under the flywheel but then it went slower in reverse. With the CDI that would not be an issue. I can't believe that place has the CDI for $5 though, wow what a deal. I think it was over $40 at a similar place was the cheapest adjustable one I could find. It does not make a huge difference though, but I ran mine down the road and open areas on stock tires, so it really ran the rpms all the time and that is where the advance seems to help more.

[harley165]

can I use this for the ig module on a G9?

[sho305]

Originally Posted by harley165

can I use this for the ig module on a G9?

It should be possible but who knows. Would have to figure out wiring, the G9 ignitor is about the same thing as a CDI and does advance the timing/etc., and they are dang expensive.

[Eriksg1]

Dude flat out awesome! Im glad im apart of this great forum! I did this same replacement / upgrade. Bought a upgrade cdi from ebay for a 50cc to 250cc motor. Took a look at your pinouts and BAM. Less than20 dollars I have a better and quicker running cart! Thank you sir.
Erik

Originally Posted by kwest0425

Out of curiosity, I was trying to figure out what was in a G1




Cap Discharge Ignition module that was worth $200-$300. I came to the conclusion.... not much, especially for a 1-cylinder, 2-stroke like the G1. The most unique thing about the G1 engine is that it (like a few others) can run backwards. I decided to try and build my own CDI.

In doing a little more research though, I came across some very inexpensive chinese CDIs for ATVs and dirt bikes. They typically come in two flavors, a 5-pin version which gets its power from the magneto source coil and a 4-pin version which is powered by the 12v system and doesn't require a source coil input.

I ordered a 5-pin CDI and a harness which I figured could be adapted to my needs. WWW.BESTGPG.COM

The pinouts on the 5-pin differ from a 6-pin yamaha oem CDI in that there is only one pulser input on the 5-pin, while the 6-pin yamaha has two, one for forward and one for reverse.

I saw a schematic in the yamaha shop manual which seemed to indicate that the two pulser inputs were simply tied together within the CDI through a couple of diodes, so I duplicated that outside the new CDI on the harness (see attached).

Anyway, the darn thing works and performance wise I can't tell the difference between the two.

Cost to Build

Component/ Supplier/ Cost

CDI and Harness/ bestgpg.com/ $14.99
1N4004 Diodes(2)/ Radio Shack/ 0.99
PC Board/ Radio Shack/ 1.99 - not really required
Snap Connectors/ Radio Shack/ 2.19

Total Cost $20.16

kwest

[henryfudaley]

So all i need to do is order those parts you posted and assemble thats it. Ill have a new cdi unit.