Converting from 7 wire CDI to 5 wire CDI

[Uglyside38]

Has anyone had any luck converting an older quad from a 7 wire CDI to the newer (and cheaper) 5 wire CDI? 

 

I have a 1988 Suzuki Quadrunner and I believe the CDI is on it's way out...🤦🏼‍♂️ A used CDI from 1988 goes for $250-$300 on the bay...and that's when you find them. The Chinese CDIs for the 1990 and up quadrunner are only about $40. I have read a blog from a guy who says it's possible and that 2 of the wires can be omitted if the rectifier is a newer one also. Any experience with this would be greatly appreciated!!!🤙

[Mech]

It looks like it might work but I don't see any reason why you would need the later regulator. Here are all the wiring diagrams for all the four wheel drive models and none of them look like they need the regulator to earth the pulse or cdi charge windings, and the battery charge windings are all insulated as well. That's the "output" pdf. This is what I think you are considering fitting.

The ohms for their stator windings are, cdi charge windings 105-160 ohms, and trigger windings 100-200.

The two wheel drive shows cdi having seven wires if you allow the coil and the cdi are both earthed by a B/w. The pdf with it's wiring diagrams is called "2WD".

The only problem might be the difference between chain and shaft driven stators because the two different stators have slightly different ranges of acceptable ohms.

For shaft drive the cdi charge windings are 150-250 ohms and the trigger coil is 70-160.

For chain drive the cdi charge windings are 150-350 ohms and the trigger coil is 100-200.

So if the stator was right at the end of it's allowable range it might be outside the range of allowances for the other cdi.

Big question.. Is your bike shaft drive or chain drive.

 

output.pdf 2WD.pdf

[Mech]

I think the biggest problem would be figuring which wire is meant to go to which pin on the new cdi. None of the diagrams show the plugs with wire colours, and it's highly likely that they will have changed the pin-outs.. they do that !

Unless you had a newer bikes wiring loom to check which colour is in which position in the cdi plug, it would be trial and error.