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