Hi Guys and gals
I recently re built top end and set up valves as directed ie open with index marks lined up.
When I turn ign on they twitch slightly ,pulleys move say 5 degrees.
Start bike nothing happens even when revved to 9,000.
My knowledge of pv is that they are shut making ex port height lower at lower revs then as revs get to more serious levels they open raising top of port and hence more speed.
I need a new pv motor or is there some connection I should check first?
I have not checked them before but last time out on track it did seem slow but got eventually up to a decent top speed 115 120 ish.
its an mc 18 early one
Any help would be good and where to get motor if I need one
TA!

It sounds like you know what you are doing. And yes, VERY basically the power valve raises the height of the exhaust port as the revs increase.
I will just list some of the basics here, which I suspect you already know. But you have to start somewhere.

1) Does the battery have a good charge? About 12.4 volts or more. Note that a single lead-acid cell gives off 2.1 volts. So 6 of them in series should give off 12.6 volts.
2) Is the drive motor stalling out due to too much mechanical resistance?
...Are the power valve cables adjusted up too tight? Maybe just slacken them a bit if they are.
...Are the power valves easy to turn by hand when not connected to the cables?
3) When you turn the ignition key on:
If powervalve is not in the "low" position, and engine kill switch is set to "Run", then powervalves will rotate to "Low" position.
However, if the TPS wires from carbies are disconnected, and engine kill switch is set to "Run", then the powervalves will rotate to "Hi" position.

I suspect that 3) above will be the stumbling point which probably points to the PV motor drive electronics in the PGM being stuffed, or the powervalve drive motor being stuffed, assuming all your electrical connections are fine.

If you disconnect the cables from the power valve drive pulley and apply 12 volts to the correct wires, (I think White and White/Black [any polarity]) you should be able to see if the power valve motor works or not as it will start spinning. Note that I haven't actually tried this myself, so don't trust me. It may be that you need to put a resistor in series with the power valve motor so as not to supply too much current to the power valve motor, if connecting it straight to your bikes battery.


Last edited by TuckerBag on Sat Apr 21, 2012 10:31 pm; edited 2 times in total

This is a bit of a long shot, but while you're at it you may as well check that the variable resistor (or potentiometer) on the power valve motor assembly is working correctly.
If you put an ohm meter across the LightGreen and Green/Blue wires I think the resistance should vary from approx 5-8 kohm as you turn it.
Likewise, if you put an ohm meter across the LightGreen and White/Red wires the resistance should vary a similar amount but in reverse.
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[color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...

Hi
Thanks for such a lot of info ! I will do whats suggested and let you know
Thanks again

If the motor is twitching it must be trying to move. I presume you cleaned the power valves when you had the top end off? If not they could be seized. It might be possible to connect the power valve cables the wrong way around as well.

If it were me I would disconnect the power valve cables and see if the pv motor moves to the open position when its disconnected.

Don't forget that at 2k rpm the power valves move to the alignment marks. If it doesn't do that then either the motor/electrics are faulty or something is restricting the operation like cables siezes or power valves carboned up
The powervalve cables disconnect easily at the cylinder end (with a reverse threaded nut). You should then be able to see if the servo operates and if the powervalves can be manually moved
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Why do things simply when you can complicate them

Hi
Have been through TUCKERBAGS advice and................

valves turn by hand freely..I had top end apart before

with cables disconnected motor spins ok when putting 12v through white/white black wires

motor is in low pos when ign on and throttle pos sensor connected BUT when diconnected stays low not high.

nothings stuck and all electrical cons good

problem is powervalves always open when bike running.

seems to me its not getting a signal regarding rpm?

OK, I'm just going to ask the simple stuff about your setup before taking this any further.
Please excuse me if I am just stating the obvious, but it is important that we all know that the basics have been carried out correctly.

When you first set the power valve positions did you:
a) Have a good fully charged battery in the bike. I stress this because I have had random troubles before that simply boiled down to a slightly crap battery. I think the NSR can be fairly temperamental when it comes to the state of charge of the battery.
b) Turn on the ignition (with the engine kill switch set to run) with the TPS and PV cables disconnected, to allow the PV electronics to set the pulley to what it thinks is the "Hi" position.
c) Without moving the power valve pulley, attach and adjust the cables so that both power valves are at the fully open position.

I am guessing that you didn't do this because something is wrong that prevents the PV electronics from rotating the PV pulley to the high position. Yes?

But the reason why I ask the a) b) and c) above is because I just want to make sure that you haven't set the powervalves to be fully open when the pulley is, say, in the fully closed position. This would give a situation where as you say: the problem is the power valves are always open when the bike is running. And the drive motor would be be fighting the mechanical movement limits of the power valves the whole time.

But if all the above is irrelevant (which I suspect it is) because you have set things up correctly, then it is time to try a new PV controller, or maybe check the signal coming from the pick-ups.
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[color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...

Thanks again for your time and info!

As the motor does work methinks as you say in second last paragraph I may have set valves open (which I did) and motor pulley was in closed position (which I didnt check!)

I will check this week and hope its that and just have a red face instead facing big bill!
Cheers

Hi
Yes I set cables with servo on low and powervalve pulley on high!!!
This proves my move from bike mechanic to landscape gardener many years ago was the right decision!!!

Cheers for help

FASTFILL wrote:
This proves my move from bike mechanic to landscape gardener many years ago was the right decision!!!

Don't worry, we've seen all sorts! Best one was one valve trying to open while the other was trying to close!
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Andy.
NSR-WORLD.COM

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