Testing a CDI?

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kobra
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Joined: Sun Sep 16, 2018 12:53 am
Location: Bay Area CA

Testing a CDI?

#1 Post by kobra » Mon Jun 17, 2019 12:44 am

Hi all
I picked up some parts from a local RZ hoarder I mean parts collector recently and in the pile was a CDI marked 29K-50. Apparently everything was from a running bike that got parted out. It turns out my RZ's CDI is a 52Y-50 with different terminals on it, so I may end up selling the one I bought.

However it would be nice to know if mine is in working condition before I tried selling it. Is this something I could easily test? Also what do these go for?

I tried searching but it's a bit overwhelming with all the versions that were made.

brrrappp
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Location: USA

Re: Testing a CDI?

#2 Post by brrrappp » Mon Jun 17, 2019 1:04 am

The testing procedure for no-spark is basically to test everything else then replace CDI with known-good unit. Meaning there isn't a test for the CDI itself.
The 84 and 85 USA models have different connectors with a slightly different color scheme. As I remember there are just two wires that were different. You should be able to make a couple of jumper wires in order to swap between CDI units. Someone here can probably tell you the wires to connect. The 85 model was more reliable and had a better more powerful advance curve programmed into the unit.

MK
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Re: Testing a CDI?

#3 Post by MK » Wed Jun 19, 2019 12:22 pm

Easiest test:
Visit someone with a 83/84 31K model and replace the CDI on his bike with yours.
If it runs properly, the CDI may be ok.
Bye
Martin

kjellz
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Re: Testing a CDI?

#4 Post by kjellz » Sun Jun 23, 2019 11:10 am

There are some companies that tests and repairs CDIs. It may be worth it only if you really need one or if they and/or if such a service can be found locally to get around shipping it back and forth vs the price of a new one.
----------------------------------
RD350 YPVS 1990
F2 converted to N2 Red/white 1986 - Figaroli pipes

kjellz
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Re: Testing a CDI?

#5 Post by kjellz » Mon Jul 01, 2019 10:00 am

By the way, do we know what ac voltage the 2 ignition source coils puts out?
----------------------------------
RD350 YPVS 1990
F2 converted to N2 Red/white 1986 - Figaroli pipes

MK
Posts: 813
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Re: Testing a CDI?

#6 Post by MK » Mon Jul 01, 2019 10:12 am

That depends on rpm and how you measure (RMS vs peak values) .
Peak voltage should be in the 50-300V range.
Bye
Martin

kjellz
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Re: Testing a CDI?

#7 Post by kjellz » Mon Jul 01, 2019 5:24 pm

I am thinking about a bench test setup. It should be doable. Supply 50vac and a signal to mimic the pick-up etc.
----------------------------------
RD350 YPVS 1990
F2 converted to N2 Red/white 1986 - Figaroli pipes

MK
Posts: 813
Joined: Sat Nov 26, 2005 11:44 am
Location: Wolfenbüttel, Germany
Contact:

Re: Testing a CDI?

#8 Post by MK » Tue Jul 02, 2019 11:45 am

I've been doing this with Ignitech CDI's by simply putting a capacitor in a row to a 12V rectangular output of a Megasquirt Jim Stim board. This was enough to mimic a VR input.

But if you ask me, I'd recommend building a driven left crank cone where you can attach the real hardware and spin it up to the required rpm. This also enables you to measure the ignition advance vs. rpm if it's an unknown setup.
Bye
Martin

kjellz
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Re: Testing a CDI?

#9 Post by kjellz » Thu Sep 19, 2019 9:02 am

I have also played with the idea of replacing the pick up coil with a Hall-effect sensor. In theory it should be possible and I learnt that the voltage of the signal will be constant and independant of rpm, but is there really any noticeable gain from that?
----------------------------------
RD350 YPVS 1990
F2 converted to N2 Red/white 1986 - Figaroli pipes

MK
Posts: 813
Joined: Sat Nov 26, 2005 11:44 am
Location: Wolfenbüttel, Germany
Contact:

Re: Testing a CDI?

#10 Post by MK » Thu Sep 19, 2019 11:39 am

The stock CDI will likely not work with a hall sensor.
Aftermarket programmable ones may will.
For example I happen to know that HPI from Belgium explicitly supports a hall input. https://www.hpi.be/index.php

Hall sensors were pretty popular in the 80's, but as long as your VR sensor is working, there's absolutely no advantage in a hall sensor.
Nowadays almost all crank or camshaft sensors are VR type as they're much cheaper than hall or optical stuff.
Bye
Martin

kjellz
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Re: Testing a CDI?

#11 Post by kjellz » Sat Sep 21, 2019 5:40 am

I thought it was the other way around - that the Hall effects were the more current solution to accompany modern digital Ignition control modules. But I have no depth insigth into this subject other the very few bikes I have repaired lately.
----------------------------------
RD350 YPVS 1990
F2 converted to N2 Red/white 1986 - Figaroli pipes

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