I got a CDI and want to bench test it to see what the thing does but I'm not sure of the connections. I'm at work so I can't go to the shop & trace my own wiring
Anybody know this well enough to post the connections?

What? You got yours already? I hope that means mine will be waitin when I get home from work too

have you looked at the wiring schematic in the Dune manual to see if the CDI connections are shown?. I'll check mine when I get home, but when all is said and done my guess is a simple resistance check across 2 wires that controls ignition timing advance will read slightly different from stock. I am going to do a quick before and after run up the street with a pace car to test mine, but if you get stuck on your electrical diagnosis hit me up and I'll try to help.

Paul

OK, mine was waiting for me when I got home. Unfortunately the wiring diagram in the manual shows few values for many resistors and no pinout numbers on the CDI. In looking at the wiring diagram in the manual- it only shows 5 connections (no in/out indicated) to the CDI, even though there are 6 terminals:

BL/R
G
BLU/W
BK
PUR

I think you can ignore the following 3 for bench testing:

G=lights
BK=ground
PUR=main lead to ignition coil

that leaves:

BL/R & BLU/W as your loop to the stator that should control timing advance I think. Trying putting an Ohm meter across those 2, then put your negative meter lead on G and touch the positive lead to BL/R & BLU/W individually and record your readings. Repeat and compare on the stock unit. The legend shows stator resistance values only and all are less than 1K Ohms, so set your meter to lowest range (1 or 2K usually) to start, then go up to 10K range if needed.

Let us know if there is a difference between the 2, or my procedure is dirty diaper

Paul

I still need to have a look at my CDI in the buggy to get the actual wire placement. The schematic is vague and the wiring colors may not be accurate. What manual (and page no.) are you looking at? I've looked at the Dune service manual and the Yerf manual (and a Twister manual). None of them show a purple wire, for instance. If you see purple, tell me where you got the manual--mine might be outdated. The Dune schematic is identical to the Yerf schematic--which means there's no ignition switch shown, or taillight. Maybe other differences...

As for my assumptions (and maybe yours?) on hookup, here's an example of wierdness: Pins 1 and 6 I assumed were power and ground. They're separated from the others, so made sense to me. Actually they're internally connected together. 0 ohms. The schematic detail on page 57 shows black/red and black/white go to "Main switch". Is that the ignition or kill switch? They short the CDI stator lead to ground? The trigger winding is shown seperately and has no switch on it. That's not how I would have done it...but then I'm not an engineer

To be continued...

Wow guys,

It's all greek to me

Myself..... I am a plug and play kind of guy. But this is what makes BuggyNews great.


The Mad Scientists bent over their workbenches in messy garages, buggy parts everywhere, working to understand the inner workings of our buggys to make them bigger, better, stronger.


Thank-you guys........

It is not relevent if the resistance is different. The CDI unit takes the raw signal from the pick-up and processes it. It will modify the signal and energize the coil telling it when to fire. A change in resistance will not alter timing. Or were you thinking it would send more voltage on the coil primary?
I'd like to know the pinout on both the 150 and 250 cdi's so I could wire in a hot 150 cdi into my 250, since no one has one for the 250.

Well these 2 signals: BL/R & BLU/W are a loop to/from the stator that should control timing advance. BOTH have resistors shown in-line on the stator circuit. I think 1, which you identify, is the pickup signal & the other is likely tachometer since the control unit has to know how fast the engine is turning as a reference for timing to pulse the coil. I suspect the relationship betweeen these 2 is a "feedback loop" and with mapped timing and a known/fixed resistance= a rev. limiter. I mentioned an in line resistor shown on both these wires AT THE STATOR, so if you wanted to go past or change the hard rev limit you would probably need to change (eliminate?) the resistance on 1 or both signal lines. So my edumacated guess is since you can't easily just go into the stator to change the resistor value- they change the value on the other end in the modified CDI to accompish the same thing

Of course I could be wrong

Paul

Paul you assume the schematic is accurate. Tsk, tsk. LOL
The "resistors" on the schematic are supposed to be coils. I guess some wet-behind-the-ears engineer couldn't be bothered trying to draw one in the traditional way. It's hilarious that the only real resistor in the buggy isn't represented by a zigzag but instead the label "resistor"! How lame.

Well Mark, I come here to learn stuff too you know Have you solved the mystery on this one yet? FWIW, my manual schematic pg. 32 gives resistance values for the stator wires I mentioned- you would expect them to be in microHenries for coils or inductors- but it could be listing bench test resistance levels for verifying if the stator unit is OK.

Paul