DT125R Not going into powerband due to possible powervalve not opening?

[TimStafford99]

my dt 12r wont go into powerband it gts up to 6k or 5and half k and boggs and splutters with no powerband
the jets have been cleared and are correct
the reeds checked and are correct
the only thing i see left is the powervalve
do you have any expierience with this or advice i can take to fixing this problem

[Calum]

@timstafford99 What makes you think it's the powervalve?

[SpookDog]

Process of elimination is only as good as how well you know what you’re eliminating...

Take the cover off of the power valve and check that it’s cycling correctly. I can only speak for my bikes year (1988~97) but it should be in the open position when ignition is off, then cycle closed, then open when the ignition is switched on...
I don’t know about newer bikes...

I’ve had bikes where the CDI has started to pack up loose their definition in revs as they break down. Does it rev above 5-6k when stationary? Is it just being ridden under load?...

[Calum]

@spookdog It doesn't sound like a powervalve issue, which is why I'm asking.

[SpookDog]

@calum
I know, it’s good if he ticks the power valve off the list of suspects tho’...

[rking7888]

Mate I had this excact problem 2 weeks ago, it was the power valve the pin had broke of the holder and the actual valve cylinder spun around to the closed position, just splutterd at 6k. Was doing my head in easy fix in the end tho

[SpookDog]

@rking7888
I didn’t think to ask if it was an early pre servo bike!
I can’t imagine how a pin breaks though. Mine never had a pin, the nut locked it to the valve in position, I think?...

[rking7888]

@spookdog
I have no idea how it would have got broke, my only idea was a previous owner thought they new what they was doing trying to adjust it lol All the pre servo powervalve covers seem to have the pin I had a nightmare finding one NOS as the part numbers changed multiple times but turned out they all superseded each other and were the same. Will post a pic of the broken one the weekend hope this all helped tho as it was driving me insane, I was convinced it was carb problems or that my air box was blocked or something as it randomly started after a very muddy day in the woods .