Testing Powevalve controller! NSR125

[RichP]

After a big strip down and clean of my NSR, as well as replacing some bits for MOT, I'm ready to put it all back together again...

However I'm determined to get to the bottom of a few problems I had before:

First off the powervalve doesn't work, I know the servo works because I tested that on a battery, I infact have two and it didn't work with either of them.

So I checked my controller and its the TV-78 so no problems there, when the bike was running I measured the voltage I was getting at the wires going into the servo, this was 12v at all the wires, including the negative.
My current thoughts are that the controller maybe faulty, does anyone know if there is a procedure to test this?

Also another issue I had was that if I left the powevalve open all the time I had a flat spot at around 5000rpm, so bad that literally in anything over 2nd gear the bike couldn't get through it, could that possibly mean the bike was running to rich?

Any help much appreciated, thanks!

[EnergyInducti...]

"Current" thoughts.... *smirks to self*
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Riding: Yamaha RXS100
Aiming for : RD350 + Test
Dream bike: Suzi RG500 Gamma

[Stowelly]

is it a swiss import NSR? mine had a similar problem, and it turned out one of the restrictions was a shunt in one of the wires that just needed removing to allow it to work again

[RichP]

Nope its a UK model, 1998, with a Powervalve controller that says TV-78 on the side, I just want to test if its defective...

[alains]

how do you know it's a UK model ?
send me a pm with your serial number (between the yokes)
i've never seen until now a faulty controler but i've seen faulty terminals by oxydation . so prior checking verify and clean every connector on both controler & CDI (CDI provides to the controler the engine speed through the red/white wire on the 3 ways connector of the controler)
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the worst day fishing is better than the best day working

[RichP]

Ok well I'm just going to pick up some parts that I need for MOT, and then I'll get you the serial number between the Yokes.
Thanks

[RichP]

Ok the number on the front forks is:

JDCJC22COWF205272

Thanks

[alains]

ok , you were right it's a NSR125RW (1998) with UK specs
download my file https://www.geneva-racing.ch/~alains/NSRtips.doc
see sequence on page 10 , but as i said previously before testing check and clean all terminals on both controler & CDI
if no cure , back to me i'll think about
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the worst day fishing is better than the best day working

[RichP]

Ok,
I've cleaned up all the terminals and the bike is back together, however power-valve still not moving...
I measured the voltage across all of the wires going into the servo, and they all read 13+ volts when the bike is running, basically all the wires have got the same voltage, equal to the positive terminal of the battery

Guess the controller could be broke?

[alains]

it's more likely the CDI . the red/white wire coming from the CDI arrives on the 3 wires connector of the controler (black,green,red/white) . this wire transmitt the turning rate of the engine and then the controler knows how the valves should be and feed the servo in one way or and other to moves the valves
i've never seen a broken controler but a CDI , yes
i reconize it's not a confortable situation because these electornic boxes are not cheap
tell me :
- do you hear a noise when you put the key on
- does the pulley move when you start engine ?
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the worst day fishing is better than the best day working

[RichP]

Nope, no noise, the servo doesn't move. Infact I can physically move it by hand without any resistance. The servo motor does work though as I tested it on a battery before fitting.

One thing that makes me think it could be the controller is, on both the plastic airbox and the controller the plastic in some places has gone really soft and mushy, my mate reckons its had a petrol spill that has damaged the plastics... This could have damaged the controller?

[alains]

first of all check if you find any voltage on the 3 wires connector (black,green,red/white) . when you put the key ON you must have 12V between black & green otherwise you must have a loose contact on the key switch or a faulty switch or a faulty connector near the switch
you can test the servo-motor and it's potentiometer
unplug it and also the light green wire , the connector shows 4 wires : white,black/white,green/blue,red/white
set multimeter on 0-10KOhms check green/blue-red/white and you should find around 6 KOhms , then you can check light green to green/blue and light green to red/white adding this 2 mesures you must find the same as green/blue-red/white
checking the motor :
attach 2 wild wires on the battery + & -
feed the servo for 2s , + on white & - on black/white (it should turn one way) then reverse polarities + on white/black & - on white (it should turn on the other way)
if nothing happens look for a second hand servo-motor . just check that it will be suitable for your bike (2 models 1989-1993 and 1993-2001)
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the worst day fishing is better than the best day working

[RichP]

Ok!
The Servo Motor works and I will carry out the other tests you suggested tomorrow.
(Potentiometer and voltages etc)

Its getting MOT'd first thing! Hope it passes

[sazzansr]

Hi - my nor has the same PV issue yours did and the servo and controller test the same as yours.

Did you solve your problem in the end? Was it the CDI?

I don't wanna spunk £140 without knowing.

Cheers ears

[alains]

buy a second hand on ebay
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the worst day fishing is better than the best day working

[sazzansr]

Eventhe second hand ones on the bay are £60 - £80. I'm not sure if there is a specific model # to fit my bike (Italian import 2000 reg), or if they are all the same?

Cheers

[sazzansr]

Would be good to hear from RichP whether replacing the CDI fixed the problem.

[Vincent]

Can the powervalves themselves seize on the NSR?

[alains]

the gears can seize especially if the servo-motor has been forced on one way or the other
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the worst day fishing is better than the best day working

[skatefreak]

Hey,
Just thought i would tune in and mention that without the power valve working, when its always open the engine will not run very well between 2,000-6,000 rpm.
Its tuned to run above and below this speed with the valve open so if it dosnt close it messes up the tuning somewhat. Thus the engine is pretty gutless untill 6,000-7,000 rpm.

Pretty normal really until you get the power valve fixed :p

-Jvr

[alains]

the closing of the valves at low RPM increase the torque until 7500 RPM is reached then you need full exhaust to increase the revs
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the worst day fishing is better than the best day working