What are the symptoms of a Bad CDI?

[olgreyhair]

Hello all. I am in the process of reviving my old 84 RZ350. I sold it to a friend 17 years ago, who rode it about 150 miles and then stored it in his shop.
The bike is back on the road with all the appropriate fluids etc, etc. done.
My issue is that since I've put it back on the road she will intermitently just die. I haven't gotten stuck on the side of the road yet, but it is very unsettling.
Usually starts on the first kick. But the other day while warming up, she just shut off. Like you turned the key off, and would not restart. The day after, started right up, went for a ride and died about 5 miles from the house. Started back up, like nothing happened and rode about 20 miles. Some days she's fine but it seems on most rides I have been having short term total failure.
I've been checking all the connections etc, but everything seems pretty good.
Don't know what else to check. The CDI is the 29K... model.
Any suggestions would be helpful.
Thanks, George

[brrrappp]

To test a cdi - Replace with known good unit.
In other words if you eliminate all other possibilities, then the cdi is likely bad.
1984 CDI is a known issue. On most bikes it is pass/fail but I have heard the RZ will do what you describe.
Primary coils can also be a issue as they sometimes will have an internal short that only happens when they get hot and expand a little.
I had a similar issue to yours on an 84 and it turned out to be neither. The prior owner had butchered the wire harness installing tiny turn signals and who knows what else. He taped it all up nice so it looked fairly stock. When I cut all the tape off I found several places where vibration or heat was allowing a short to ground causing misfires and failure to start.
Look at your fuse box. The metal fuse holders fall apart starting at about 10 years of age.
Check the wire harness
do an ohm test on all of the coils
Replace the plug caps
The 85 CDI will work but requires some wires to be swapped around- there is a thread a year or two ago discussing this swap.

[olgreyhair]

Thanks. I'll do some tests and report back.

[kpke]

Here is a recent thread that discusses some of the bad CDI symptoms toward the end of the thread.

viewtopic.php?f=1&t=16766&p=171176#p171176

[olgreyhair]

I have heard now of squeezing the cdi unit with hose clamps and a dowel.
Does anybody have any details on this little hack?

[brrrappp]

I have heard now of squeezing the cdi unit with hose clamps and a dowel.
Does anybody have any details on this little hack?

I don't know about this "hack" but I know the difference between a temporary, just get me home fix and a REAL fix.
If the problem is intermittent, you will need to ride to determine if it works. What if the bike cuts out as you are making a pass or crossing an intersection?

I think the guy at RZsunlimited have figured out how to repair the 84 cdi.

Also, search this forum. I seem to recall a discussion about the issue that also had a resolution that didn't require a new box or a aftermarket iggy.

[olgreyhair]

Sad to say it appears rzsunlimited is "permanently closed"
But I will search this forum. Thanks

[olgreyhair]

OK. So I took a moment to measure my ignition coil resistence.
Primary side spec is 0.3 +/-
I measured 0.3

Secondary side spec is 3.5K +/- 20% (2.8 to 4.2)
I measured 2.2K, plug cap to plug cap (non resistor plug caps).

So it seems I am a bit low. Any thought? Is that far enough out of spec to warrant coil replacement?
thanks, george

[brrrappp]

Take the plug caps off, trim 1/4-1/2 inch off the high-voltage lead wires and poke your test meter's lead right into the wire core.
It could be as simple as A $5 Plug cap.

[Bald Anthony]

Sad to say it appears rzsunlimited is "permanently closed"
But I will search this forum. Thanks

RZ'S Unlimited repaired my CDI. No more problems. Just call them.

818-502-1919


BA

[ief]

Or do it yourself.

cdi repair.png (8.76 KiB) Viewed 1621 times

[olgreyhair]

once you get it opened up. How obvious are the parts that need to be resoldered?
Any photos available? There's alot of cirquitry in there I presume

[silverstrom]

Repair video here: https://www.youtube.com/watch?v=v7OG8v94eBU

[thumper580]

Buy a new one from Ed Toomey. Has his own units. He can program them for stock, moderate mods or race. My 29k was crapping out and I got one if his.... No problems now.

[MK]

They are not "his own".
He sells plug & play kits utilizing a tailored harness and an Ignitech unit (DC CDI P2 Race).
The big advantage for Joe Average: You don't have to program or wire up anything
The big disadvantage: It's that service you pay for. The naked CDI is cheaper if purchased from Czech Republic.