From: glenb900 on
Yamaha (RD350 YPVS or also called the RZ350) CDI problem FIX?

Yamaha RZ350's (especially 1983 and 1984 models) have a CDI problem
causes it to fail over time. A used unit from a a newer model don't
unless you replace most electrics. I heard of some people fixing this
problem by taking the CDI apart and replacing or soldering the
fault. It's hard to take the CDI apart but I never seen anyone release
fix or a schematic of the CDI with test procedures.

Does anyone have a schematic/circuit details or know how to test, FIX

All the info I have listed here I found posted in newsgroups, etc but
does not include repair info. If you change the stator/CDI/coils from a
newer model, it will work BUT it would be nice to know how or why the
units are failing and what (transistor/diode/resistor) needs to be

PLEASE post any technical info about this problem.
I'm interested mainly in the 1983/84 CDI info. New CDI's also have
problems but
don't have a high failure rate like the 1983/84 models. Someone below
also said they fix the problem but never posted the fix and the e-mail
1997 don't work anymore.


>> jmar...(a) (John W. Markus) writes...
>> > The bike occasionally runs fine, but eventually dies.
>> > When he's riding along, the bike will start sputtering.
>> > If he keeps the clutch out, it's like the bike is running
>> > out of gas. If the clutch is pulled in, the tach goes
>> > crazy for a bit, then drops to 0.

This may sound obvious, but did you check the spark after it cut out.
Supposedly there was a design flaw in the cdi box that caused them to
fail at a high rate. My bike has a broken box. Have to preheat the box
or park under the hot sun for it to start. If you have a bad cdi, it's
$$$ to replace.


> Yes, once it was the black box. Try to borrow one that you know works
> and try it.

My second CDI box quit this summer. BUT I fixed it !!!
Took a couple of hours to dig through the epoxy and gravel but I
have fixed it. I am about to attempt this on another box in a couple
of weeks. Do not throw away your CDI boxes just yet. Just in case
I have actually figured out how to fix them and it aint just a fluke.


i assumed that the YPVS and
ignition system would be nearly identical. I could not find any spec
regarding the CDI unit, in fact the manual stated that Yamaha had not
released details at the date of publication?


tighten a large hose type clamp with a dowel on top mid-point applies
to the circuit board in the CDI for it to work again. This is ONLY a
temp fix
so you can find a replacement or fix your old one.

Three CDI types on Yamaha RZ350:

29K-50 for 31K 1983-1984 RZ350
52Y-50 for 57V/1JF 1985-1986 RZ350
1UA-50 for 1WT/1UA/3DH1 1987 on ?

From: The Older Gentleman on
<glenb900(a)> wrote:

> PLEASE post any technical info about this problem.

Try again, this time with a comprehensible posting.

Trophy 1200 750SS CB400F CD250 Z650
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