250-500cc WR 250/300 Power Valve adjustment Pictures

First off, I got these pics from someone else on adjusting the power valve. I posted somewhere else and they disappeared from that link.

make this tool out of plastic and mark your measurements.


Place here


measure here


adjust here

It's been a very long time since I have done this since I don't have this bike anymore.



shameless plug as I always liked this picture of my bike before I owned it. This is the cost of me showing you the adjustment pictures!!

YES

So how do you make the valve adjust down to 50.5mm? When you loosen the bolt under the right hand cover, will the valve become loose?

and what does the adjustment achieve????

It changes where the power is delivered.

So I went and tackled this little project.

The PV was gross on the right side.


Removing the head


Head removed.


Cleaned the PV adjustment


Then checked the gap and adjusted to 50.5mm.


Put it all back together.


I really hope it makes some sort of improvement. It was pretty easy to do. It can be done with the tank on too.

Just for the record, these pics came from a guy a long time ago (I think from TT days). Thinking about it now, I don't think I ever did this to my WR 250. Let us know how it turns out.

If the power valve is closed more technically it should give it more bottom but the valve can only open so far before the side ports start closing again, I think the only way the delivery can be changed is with a stiffer/lighter spring or one of those really expensive mods

Did this to mine ages ago, difference was night and day. Mine was already 50.5 so I tried 48, no response off bottom in comparison but comes on pipe sooner in feel. 50.5 is what makes these things fun in the single

So... setting it at 50.5 will make the bottom end more responsive?
My 300 is lazy off idle and I'd like a little more snap. Which setting should it be at?

And thanks for posting this!

Play around with different pilot jets and needles, you can move the power all around

Since the main flapper can open to the point where the side ports start closing again, should the opening limit be set at the point where the side ports are fully open? Or where the main flapper is fully open (and side ports are partially closing)?

Yes, older 250's recommended 50.5 in manual, newer 48mm.

I found the main flapper recedes into the top, so i set it flush which corresponds to side ports being happy too.

Quick question just to confirm PV setup. When the PV is fully open, the side ports are also fully open correct? And the opposite , when closed to 50.5, the side ports are fully closed?

Does anyone know what the correct position of the little sprocket is?
The power valve axle came off tonight when we were looking for better access to a piston ring, which had a problem during installation.
We can see small dots on the sprockets both sides, but we don't know which position it had.
The dot on the sprocket, with what does it correspond?
Below a copy of the picture that was posted in this topic before, not sure if this the correct position..
Thank you.

That's my pic. From what I found is NO, it doesn't matter. It spins freely. And now it runs awesome. With the adjustment, it's running with great bottom end power. It has what I've been trying to find. With the Gnarly pipe it's almost too much low end with stock gearing. For faster trails I'll switch to my Doma. I'm very pleased with the change.

There is also a dot on the arm about the third tooth down. Put them so they face each other.
Make sure it is the same as the other side so they both open together.

Awesome!
Thanks for your swift reply!!

I'm a little confused,do I want to adjust to 50.5 or 48mm.its a 2012 wr300

My manual says 50.5 for off-road and 48 for motocross. (50.5 for better low end, 48 for better high end) Mine was set at 48 from factory. When I changed it to 50.5 it did increase low end power a small but noticable amount.

So by going to 50.5 you are lowering the lower edge of the power valve making the port smaller and more restricted. In turn delaying the opening of the valve and increasing low end? I'm still a little fuzzy on where to adjust the pv.