YPVS Loses Position(?)

[2steve]

Took the tank off the RZ for lining and 2K clear coat. Not to make it pretty, but to make it hold gas fumes inside instead of bubbling up the paint in a couple spots. Also, ordered a new needle from Toomey because the left one looked a little chewed up. Installed that. Put it all together and rode around the neighborhood.

The YPVS had previously been a little off, so I got it lined up before ever taking off the tank.

While rolling on it in 1st or 2nd, it seems to bog, (or be missing a lot of torque). Then suddenly, about when the YPVS should have done it's thing and is getting out of the way, there is a sudden torque hit. I mean light switch sudden. Learned to lean over the tank just to compensate for that.

Got back to the house (twice) and the YPVS is full clockwise with the engine off. Should be at counter-clockwise "home" position. Turned the key on and instead of 2 moves turning clockwise to open and then back to home, it makes three moves and DOES find home position by itself. Both times. Seems like it should be fine. Why would something go wrong?

Then, what did I do? Maybe disturbed a wire? This was a carb and tank related exercise. Maybe #1 and #2 YPVS cables became too tight and caught up with me?

If any clues, please let me know.

[1976RD400C]

If something disrupts the bikes battery power or the bike stalls the powervalve may sequence differently. Cable adjustment should be take up the slack and then back off the cable adjusters a 1/4 turn to prevent any drag.

[m in sc]

your power valve controller sounds like it took a shit, or the servo is having an issue (if the wiring mentioned above is all ok).

[elliottles1]

hi,
if it turns out that the control box is toast (ive had one go after a reg/rect failure) there is a guy in Greece who repairs/modifies them with a switch box to play with the valve timing, i highly recommend him, did a great job on mine.

https://www.ebay.co.uk/itm/277019422206?_skw=tzr+power+valve+controller&itmmeta=01JW886RNA7RZYH9H1R5QJ0Q72&hash=item407fa4edfe:g:kpAAAOSwy4hUR7Y5&itmprp=enc%3AAQAKAAABAFkggFvd1GGDu0w3yXCmi1eTynOTiN6ENN%2FDnZ4OWn%2FNLKHjJkPx3P9x7WNN2wEoXej1sR2THJwulVimrA7ZRUp0uAXtixK4jx%2BdjtPQjybO%2FZFp5tmxOdPqaehYqVbsqROe3%2Bnl%2FPjagS8Vof%2Fi3vkwqTab2hfZ5YCbWYL54bNZ5v4wmFzZB2FJBsP%2FWSbY98ft5yq6V98xhpLtCletkJcwwzHTHO9DMsBSCh6RhSVjBtL6Rt7WicBFtzfrXPq4gAJOVkzkCcI%2F8YTllPvIUsm10o0Rrvm5wGpn8XSUVC8N9fTI8Ris64BK%2BABm8Na0PREEe24936QlXG5t%2B3vFzJU%3D%7Ctkp%3ABk9SR-iKm4jiZQ

cheers
les.

[2steve]

Loosened up the cables a bit and checked that it was coming to rest in the right place last night.
The bike didn't stall out, but almost did on both rides. I could hear the YPVS hunting around as it was idling way too slow. Hoping that's what the prob was. Will have to report back later.

Also seeing where someone replaced the transistors on the board and "restored" the controller.

That looks really good, Les. Simple programmability, too. Priced pretty good for that. Thanks!

[m in sc]

if you're still running a stock cdi as well, just get a zeeltronic that does both. 40byear old electronics are time bombs. 0.02

[RDnuTZ]

How old are the PV cables? when I had to rebuild my PV assembly due to O-ring leaks initially (also found slop where the clamp mated halves together) and reassembled everything according to the manual. I lubed the cables like I always did with other cables and they slid easily inside the sheaths. However, I couldn't get everything to stay adjusted correctly after multiple tries and test rides.

Did some more digging and came across instructions for a "drop test". Hold cable vertically, pull wire all the way up, then see if wire drops by itself with no friction/restrictions. They did drop but tiny bit slowly. I bought new cables and repeated drop test- comparing new vs. old and it was night & day difference. Installed new cables, adjusted everything per manual and it worked perfect and never lost adjustment again. Couldn't believe that little bit of restriction in old cables made THAT much of a difference but it did!

[2steve]

The cables have seen better days, I'm sure. Sounds like a concern that should be addressed.

Hoping that Zeel money won't have to be spent...

I'll be taking the cover off and revving it to watch valve movement, too.

[m in sc]

zeel money is smart money spent. 

[2steve]

zeel money is smart money spent. 

You can increase the area under the hp/torque curve, right?

I'll tear into the carbs again, just to see if something is amiss. YPVS seems to be moving appropriately. Carbs were synced mechanically, (although the right slide has a longer overall stroke length ) Gonna compare the carb internal lever lengths to see what gives.

Always room for an error on my part.
...hits so hard on the power band.

[m in sc]

yes you can move the pv positioning and timing curve.  also, programmable rev limit and add a shift light. when I got my tzr was the 1st thing I ordered even though the stock stuff worked

[mnein]

40 year old electronics, sorry Heave. You should probably blame the guy who sold you this turd.
As a side note, Steve and I were at the same college 45 years ago so we go back a ways. I sold him the above RZ last summer, and I reserve the right to make fun of him when he has trouble with it. Having said that, I pray the ancient electronics turn out ok so he's not forced into zeel money. Rock on Steve, keep us updated.

[2steve]

Oh, it ran great until now. I'm into the carbs and everything is looking fine - so far. Double checking needle heights later, but they were sticking through the mains the same on both sides.
The power valve cycles and goes closed when it starts. Then, doesn't really budge until rpm goes to the power band range. Maybe I'm missing the opening steps in between.
Would be cool to drop in a known good YPVS controller to check before spending the dollars.
So, not discouraged, just feeling challenged. It's an old friend that needs some new parts.

[m in sc]

they work till they don't. I remember..12? 15? years ago, or so,  the kaw triple guys saying the cdis were bulletproof.. till they weren't.  we just went thru this w Josh's 85. it had 3 issues, one was the pv controller,  the other was a bad stator. THAT was fun to diagnose.  also throw in a missing half moon c clip for the crank. 

[1976RD400C]

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.