Hi Everyone,
I've checked the FAQs but no joy. My powervalve moves clockwise when you blip the thottle, at certain revs(over 2/2.5K) it then changes and goes anti-clockwise to what looks like fully open at full throttle. Is this normal? The PV marks are aligned correctly and the valve moves freely by hand. The video link on here doesn't show the valve moving clockwise at low revs either.

It's a MK3.

Doesn't sound right but I've not looked closely at a Mk3 powervalve operation. As to what is the problem if it is a fault - I don't know. It could be several things.

I would just use it until it becomes a major issue or something breaks.

Other suggestions .

I believe that to be the norm. I don't think, as would be reasonable to assume, that when running they settle into what we would think to be a fully closed position , feck, when I was typing that it made perfect sense to me, now reading it back it just sounds like gobbly gook.
Mike

lccpmj wrote:I've checked the FAQs but no joy. My powervalve moves clockwise when you blip the thottle, at certain revs(over 2/2.5K) it then changes and goes anti-clockwise to what looks like fully open at full throttle. Is this normal?

Yes, it's normal.
The exhaust valve has a certain cycle and closes or opens at different revs.
Don't worry, there is nothing wrong with your unit.

The actual problems that may happen are:
1) Malfunctioning servo.
Symptom = no movement of the exhaust valve at all.

2) Malfunctioning PGM unit.
Symptom = no movement of the exhaust valve at all.

3) Partly malfunctioning PGM unit.
Symptom = when you manually move the power valve anti-clockwise and then you crank the bike, power valve goes to the lower position but doesn't move any more as you rev the bike.

mike stop drinking the chainsaw oil

Blimey, was I right,
Mike

Interestingly my Mk1 starts with fully clockwise at idle and then moves progressively anticlockwise. It all happens in a bit of a rush with no load but you can get to a throttle opening where the PV pulses part way through the cycle of fully closed to fully open.

I might slightly misunderstood the first post.

lccpmj,
do you mean that when slightly blipping the throttle the exhaust valve moves clockwise.

I can think a couple reasons for that, I think.

I have seen similar problems with bikes that have electrical issues.
The electric power at idle is not enough to make the servo and controller work, so by slightly raising the revs, more power is produced and the unit resets to start point and rapidly moves to where it should be. Something similar with your lights at idle, they are not as good as over 2K rpms.

On the other hand, this might be the norm on MK3 bikes.
I have seen something similar on some Yamaha dirt bikes, the exhaust valves move opposite than they should for a small range of rpms.
I've never understand the reason for the that. The only reasonable explanation that I've heard is that it helps on keeping the exhaust valves clean.

Thanks Guys,
I just assumed that when the throttle is opened the valve arm would move anti-clockwise from closed to fully open. I only bought the bike a few weeks ago, so I'm in the process of cleaning, resetting everything back to factory settings and remembering how 2 strokes work again.

I might adjust the PV cables so that the alignment of the PV arm is lower than normal and see if it still swings clockwise at revs under 2-3K.

The PV moves with revs not the opening of the throttle.

Yeah, sorry I meant with the engine running when the throttle is opened. I think I'll clean and oil the PV cables first before expeimenting with different PV positions.

lccpmj wrote:Yeah, sorry I meant with the engine running when the throttle is opened. I think I'll clean and oil the PV cables first before expeimenting with different PV positions.

Wise, they tend to get overlooked in maintenance schedules.
Mike