From Norbos post -
This is an attempt at a translation of "Martin Kieltsch rd bible. For experimental use only. I am not responsible if this information is incorrect because of any error. The following info was given to me from some one of the FORUM . I have not tryed this my self but beleve it to be correct.
The YPVS series have three different stators, rotors and CDI units
83-84 RZ350
The CDI of the first two years of construction (' 83 and ' 84) carries the marking 29 K-50. The 29K-50 CDI has a square four-fold plug, a t-shaped connector for the load coil (brown, green and red) , a two-fold plug for the Pick UP and a black ground wire. One can recognize the stator (marking ÇY) by the appearance of the load coils. This stator has a thicker coil in the center and on the right of and on the left of two smaller, which are curved like horns. The stator is marked ÇY and/or 2CY. It has two drillings and two long holes. The rotor has the marking 29L - 50
85 RZ350The 1985 31K has changed Stator and CDI. The CDI is marked 52 Y-50. The 52 Y-50 CDI has also only 8 connections (the other two to have 9). This CDI is missing the black-and-white cable, which serves to turn the engine off by the kill switch. The 85 stator is marked ÈZ or 8DX. The stator has two somewhat thicker load coils. Safe distinguisher of the 85 stator is the red-white cable at the load coil, which is always red with both other stators! A further indication is the missing connector for the "load coil", which into three individual plugs (brown, green and red-white) is divided. The Rotor has the marking 51L - 50 .86-95 RZ/RD350
The 86-95 CDI are marked 1UA - 50. The Stator looks outwardly like the ' 85 stator,but it has different plugs. A square four-fold plug, a flat connector for the load coil (brown, green and red) , a flat two-fold plug for the Pick UP and a black ground wire. The marking on the stator is 1FX. The rotor may posess the markings 1UA, -50,VCD 88,(1FY).
Combinations:The 86+ Stator functions only with the suitable rotor(VCD 88);The 86+ 1UA - 50 CDI will work without changes with a 85 31K bike. . The black white cable can remain free.
One can also use the 1UA-50 CDI with the 83/'84 31K stator(ÇY/2CY). In addition one must change the plugs going by that the cables "red" and "green" of the load coil must be exchanged . If one connects same colors, she does not function!
One can use the 85 (52Y- 50) CDI with the 84 or 86+ models. To connect an 85 cdi to an 86+ one connects the same colors and also put the black-and-white cable of the wiring harness to the black-yellow cable of the CDI. A second possibility is, black-and-white cables to the red cable to the CDI to also put (it functions both).To use an 85(52Y- 50) CDI on an 83-84 31K system you must exchange the colors red and green and put additionally the black-and-white cable of the wiring harness also to the black-yellow cable of the CDI. A second possibility is again to also put the black-and-white cable to the red cable to the CDI.
If the black-and-white cable remains free, one cannot turn the engine off
Chart Cipher:
The 84 29K- 50 CDI will work with an 84 stator and an 85 rotor.
The 85 52Y- 50 CDI will work with with the 84 rotor and 84 stator if you exchange R/Gr , S/W at S/G
The 85 52Y- 50 CDI will work with 85 rotor with 84 stator if you exchangeR/Gr , S/W at S/G
The 85 52Y- 50 CDI will work with 84 rotor with an 85 stator.
The 85 52Y- 50 CDI will work with an 86+ rotor with an 86+ Stator if you S/W at S/G
The 86+ 1UA- 50 CDI will work with an 84 rotor and an 84 stator if youexchange R/Gr .
The 86+ 1UA- 50 CDI will work with an with an 85 rotor with an 84 stator if you exchange R/Gr
The 86+ 1UA- 50 CDI will work with an 84 rotor with an 85 stator
The 86+ 1UA- 50 CDI will work with an 85 rotor and an 85 stator
The only thing I can't figure is what "S/W at S/G" stands for. Stripe?.....hmmmm
s/w = black/white
s/g = black/yellow
There is at least 3 CDI types on YPVS 350 Models:
29K-50 for 31K 83-84
52Y-50 for 57V/1JF 85-86
1UA-50 for 1WT / 1UA / 3DH1
? for 4CE6 (RD350R).
CDI Troubleshooting:
CDI theory
The CDI ignition takes a pulsed current generated by the low or high-speed charge coil (depending on engine RPM) and charges a capacitor. This stored charge is then discharged into the primary winding of the ignition coil causing the plugs to spark (both at once). The timing of this discharge to the coil is triggered by the arrival of a small electrical pulse generated by the pickup coil and electronically delayed to occur at the proper time by circuits internal to the CDI module. The ignition, engine run and side stand control unit provide a circuit to ground to "kill" the ignition. There is an old saying "garbage in equals garbage out" If any of these signals are missing or a short circuit to ground occurs in the "kill" circuit, the CDI will be unable to function properly.
Engine mechanical:
Suspected ignition problems are sometimes not that at all but other engine mechanical failures so before we test electricals lets first check the following basic items:
1. Engine has good compression and the difference between cylinders is small. Upper 90's for PSI is good for a cold engine (5 kicks with throttle wide open).
2. Carbs are mechanically balanced.
3. Check auto lube pump adjustment
4. Install a set of NEW plugs. The secondary winding of the ignition coil is attached to both plugs. In order to complete the circuit the current must flow down one plug wire to the plug, jump the gap, go thru the engine cylinder head to the other plug, jump that gap then go back up the wire to the coil. If you interrupt this circuit, neither plug will fire. If you do experience one plug sparking without the other, the circuit is being completed another way, perhaps through the plug wire insulation to the frame or perhaps internal to the ignition coil to the metal core which is bolted to the frame.
Engine electrical:
The RZ electrical connectors can corrode pretty bad. The engine vibration helps to maintain good contact but a bike that has set for a while can develop electrical "ghosts" quite easily. So lets start by separating, inspecting and re connecting all the electrical connections associated with the ignition system. When that is completed take the following readings. The following readings can be taken using the standard test leads that come with most digital volt ohmmeters. The RZ electrical system is connected together with molded nylon "molex" or "spaid" connectors. All the initial readings are taken with the circuit under their normal electrical load. This means that all the connectors are connected and you take the reading by sliding the test probe tip into the molded connector alongside the proper colored wire until it makes contact with the metal portion of the electrical connector. You need a digital voltmeter as the delay in the needle reaction of an analog meter might miss some of these very small signals
1. On the CDI bundle find the connector with the black wire with a white stripe running along it. Put the red test lead in along side this wire. Hold the black lead against the bare metal of a head bolt. Set the meter to read resistance. With the kickstand up, engine in neutral, the kill switch set to run and the ignition key to on you should see greater than 30K OHMS of resistance. If you turn off the key or kill switch the resistance should decrease to near 0.
ALL OF THE FOLLOWING READINGS ARE TAKEN DURING 5 RAPID KICKS! The object is to keep the engine rotating long enough for the digital meter to sample the signal and display a reading. This is easiest with the spark plugs removed, the plug wires connected to the plugs and the plug body connected to ground on the engine case to complete the circuit. What also works well is to tape the metal bodies of 2 spark plugs together, with the insulators pointing away from each other. Attach the spark plug wires to these and this will also complete the coil secondary circuit.
2. On the end of the CDI wiring harness you will find a 3-wire connector that has a brown, red and green wire. Slide your black probe in beside the brown wire and the red probe in beside the green wire. This is your low speed winding. Set the meter to read AC volts, turn on the ignition and kick the machine over 5 times quickly. You should see, while kicking, a reading of 25 Volts AC.
3. Now move the red test lead to the red wire (measuring brown to red) this is the high speed winding kick over the machine with the ignition on and you should see 4.5 Volts AC.
4. On the CDI bundle there is a 2-wire connector with a white with red stripe wire and a white with green stripe wire. This is your pickup coil connector. Slide your test leads in beside these 2 wires. When you kick the starter rapidly you should see 0.3 Volts AC
5. On the CDI bundle there is a 2-wire connector with an orange wire and a black wire. Slide the meter probes in beside these wires. This is the CDI output to the ignition coil primary winding.
When the starter is kicked rapidly, you should see 0.4 Volts AC.
If any of these voltages are missing one of 2 things is happening. Either the source device is not generating the signal or the destination device is shorted and the signal is being loaded down. If one of the signals is missing, separate the electrical connector for that signal (electrically unload it) and connect your meter to the source side and repeat the test. Here are the unloaded readings for the above listed signals
2. Low speed charge coil 50 Volts AC unloaded
3. High speed charge coil 4.5 Volts AC unloaded
4. Pickup coil 0.3 Volts AC unloaded
5. CDI output 24 Volts AC unloaded
In the case of signals 2,3 and 4 if the loaded test is bad and the unloaded test is good do a resistance test of the source device. The low speed coil (test 2) should read 225 ohms (or 133 ohms depending on engine type). The high-speed coil (test 3) should read 5.3 ohms and the pickup coil (test 4) should read 115 ohms. If the resistance check is good the CDI is most likely at fault.
In case the signal 5 load test is bad and the unloaded test is good, measure the resistance of the ignition coil primary winding. The primary winding resistance is around 0.33 ohms. If it is OK then the CDI is most likely at fault.
If all the above readings are good then check the secondary winding of the ignition coil, the measurement from one plug cap to the other should be about 23K ohms. The plug caps themselves "screw" (twist counterclockwise) off of the plug wires each plug cap should read about 10K ohm when measured by itself. The coil and plug wires alone should read 3.5K ohms. It is possible for the coil secondary to be breaking down under high voltage but measure just fine with the ohmmeter. If you are getting the proper signal on the black and orange wire to the coil with no spark out into NEW plugs, then the coil is probably at fault. I had this happen intermittently for about a year, I finally found it by connecting up a meter to the black and orange wires and taping it to the tank where I could see it. The next time the bike quit, while I was coasting in gear the input voltage was still there with no spark out, Good in, garbage out. told me it was the coil. One final word of caution. DO NOT ATTEMPT TO MEASURE THE OUTPUT SPARK VOLTAGE FROM THE IGNITION COIL! IT WILL DESTROY THE METER!
CDI CONVERSIONS
? for 4CE6 (RD350R). 
