YPVS Loses Position(?)

[2steve]

Mine with a Zeel controller cycles when you turn the key on and seems to come back to where it was with the key off. Start bike and it hasn't moved. At 5000 it starts to rotate, 6000 and away it goes and really cranks open.

Actually, that might be just what mine is doing with the revs going up.
I'll watch it while having someone else rev 5 - 6k.
Will raise the needles back up 1/2 step too.
There's still the possibility that it's something stupid simple.

My '74 H1 CDI went bad. I was in college and electronics nerd Ralph down the hall fixed it for me. He had me pick out all the potting first and attained instant hero status.

[mnein]

I forgot about Ralph and the resurrection of the H1 cdi box. I bet not many people try that route.

[2steve]

Assembled everything after going through the carbs again. Terrorized the neighborhood and starting to conclude that a cylinder must be dropping out. Starts/idles great, struggles through the low range (apparently on one cylinder) and furiously breaks loose from 6000+ rpm.
Plugs look good, they are gapped right. Left cylinder on the temp gun is a little cooler.
Not the coil, I assume.
Once the drop-out starts, it doesn't recover until the higher rpm.
Will look behind the left crank end cover just to do something.
Off on another path.

Does the RZ have ignition timing control that could have a segment of rpm drop out, due to loss of output?

Thank you guys for the seasoned suggestions!
Matt, this bike is too beautiful to be a turd.

[m in sc]

again, did this recently. 99% sure on that the stator was going. swap could leads see of it follows.

[2steve]

Mark, I see your post on swapping leads and don't know what to swap without changing the wrong thing.

I envision doing that, having the same problem but with the other cylinder, and verifying with the temp gun. Then, not knowing what to look for to fix it.

[m in sc]

if it does that its either the plug leads, plug cap or coil itself. since rz coils have the wire encased, its sort of a 'if the wires bad the coil prob needs to go'.

... keep in mind, the 1st thing i did when i got my tzr was get a new coil and zeeltronic right off the bat even though the stock ones worked well. i don't want to find out on a ride. i say this because i want to illustrate that i practice what i preach. 40 ish years is about the life expectancy of these components, it just is in my experience. 

[2steve]

Ordering a coil assbly, plug caps and YPVS cables from Yambits before doing anything else 

[2steve]

RZ plugs are supposed to be BR8ES.
Mine is running B8ES, but with 5kΩ caps.

*** 5k NGK resistor caps OR resistor is the same either way? ***
Don't want to overstress the coil - if that's a thing.

Yambits shipped Monday. Stuff arrived Wednesday, FedEx. They are hitting on all cylinders.

[2steve]

New Yambits parts did not help. Left cylinder seems to be what drops out - it's a little cooler after the laborious ride in the neighborhood and the plug is wet while the right is dry. New Yambits "stock" coil, which includes wires, and new 5kΩ caps.

Idles fine, struggles while loaded at low to mid rpm and then it's serious rocketship time at 6k or so. Kinda hairy.

Plugs are B8ES, (not BR8ES like the manual says - see question in the post above), and they ohm out/show continuity like non-resistor plugs should, gapped and looking like new too.

I have a 1985 52Y cdi, but it is 40+ years old now. YPVS under observation looks like it is doing exactly what it should.

Having the understanding now that both plugs fire every 1/2 rpm, the bias toward the left side struggling to fire is a mystery - UNLESS there's a problem with triggering during the timing of the left cylinder. Why it fixes itself just in time for the power band is  .

Left cover comes off next to look at the flywheel trigger sitch. Maybe some of you brilliant dudes or chicks know something. [Remember Heather Dakota Gurl?]

I had an RZ back when it was fresh and new. This one, at 40 yrs old, is a learning curve.

...DO I NEED a new left carb "choke"/enrichener assembly? It looks like it's okay, but is original and seen better days.

Matt, I'm pleased with the result of your rebuild. It's well assembled and tight.

[m in sc]

test your stator windings.

[mnein]

Steve hope you can narrow down what's going on. I don't even know what to suggest other than throwing parts at it. You certainly need the advice of this forum cause I'm not smart enough to help you. Keep on, you'll get it sooner or later.

[2steve]

3 stator windings seemed to settle at 0.2Ω across each other at 75F, 3 white wires.
Consistent, but not the 0.4Ω that the book says at 68F.
Seems ok.
Gonna order a new enrichener-knob assembly since it seems to be the left carb. Cheap from eBay. Not counting on it doing any good.

[m in sc]

you measured the charging system windings, not the ignition windings. 

[2steve]

Assuming (guessing) that I check resistance across the "High Speed Charge Coil" and "Low Speed Charge Coil"
Maybe Red across Green and Brown across Green?
Manual doesn't define which is high and which is low:

[m in sc]

yes, check all those.

the 2 whites 'together' are (alternator) battery charging. high speed and low speed coil are what you are looking to test. they call it a charge coil because it charges the capacitor.