250-500cc WR250 power valve adjustment?

[dartyppyt]

I did mine @ the 50.5 last year. I bought one of those machinist rulers with the slide @ one of the Home improvement stores. It was either set wrong at the factory or slipped. What a difference it made along with crisp jetting.

 

[Bench Racer 117]

Is it worth doing? What kind of difference did it make? Low end? Better all around power?

 

[dartyppyt]

It gave me a crisper bottom end up thru the mid. I wish I would of checked it when it was new.

 

[lankydoug]

The PWK 38 did seem to help on my '07 WR 250 as well. The bike did seem smoother with less violent hit. As far as adjusting the power valve height, here is some information that came from either a member here or TT. I am sorry I do not remember who to give credit to. Hope this helps. If adjusting this be extra careful that the power valves are not so close as to rub the piston skirt.

1. Remove seat, gas tank, right side cover, silencer and pipe
2. Remove radiator cap and drain coolant
3. Remove upper motor mount and spark plug
4. Disconnect coolant hoses from head
5. Remove head and right PV cover
6. Move piston to bottom of stroke
7. Measure from bottom of PV to top of cylinder. See photos
8. You will need to improvise an accurate method of measuring. I made a small L-shaped plastic ruler with two marks for the settings I use. The short leg of the L needs to be just long enough to grab the edge of the PV. See photo
9. Make sure PV adjustment arm is bottomed against case when measuring. See photo.
10. Loosen bolts and adjust PV height.

I use 48.0mm for MX. It gives great top end power at the expense of bottom and mid.
I use 50.5mm for woods riding. Good grunt, but not as much peak power or revs.

[/IMG]

[/IMG]

[/IMG]

[/IMG]

for some reason I can't view any of the images that you posted.

 

[2stroked]

I still have the TMX, with a JD kit and a 4.0 slide, Gnarly pipe and I have ridden a friends with the PWK and there wasn't much difference but they are a little finicky for sure.

 

[raisrx251]

for some reason I can't view any of the images that you posted.

I am having trouble finding the pictures as well on my computer. I will look on a backup hard drive and see if I have them. Really all it showed was the plastic ruler setting in the cylinder measuring to the top.

 

[Steve-oh]

No images as well ???

 

[oneal]

Great posts but the pictures aren't showing

 

[Cosmokenney]

I still have the TMX, with a JD kit and a 4.0 slide, Gnarly pipe and I have ridden a friends with the PWK and there wasn't much difference but they are a little finicky for sure.

What's a 4.0 slide?

 

[NCSteve]

haha...it's the part of the carb that slides up and down

 

[Jhunter]

Here's my 2 cents... Find some 90 octane gas without Ethanol (corn). Second, purchase a JD Jet kit for $75. That combo will work wonders on your motor. Cheap easy fix and can be done in less than an hour

 

[flyingbob]

Here's my 2 cents... Find some 90 octane gas without Ethanol (corn). Second, purchase a JD Jet kit for $75. That combo will work wonders on your motor. Cheap easy fix and can be done in less than an hour

Maybe it's been posted elsewhere, but I was told you can buy non-ethanol gas at any marina. I haven't checked, but soon will.

 

[lankydoug]

Here is a link to a free app that will help you find no ethanol gas
https://itunes.apple.com/us/app/pure-gas/id454559068?mt=8

 

[shrubitup]

or www.pure-gas.org

 

[Cosmokenney]

13 Pure Gas Stations in California, every single one is in Southern California

 

[lankydoug]

13 Pure Gas Stations in California, every single one is in Southern California

The app is updated by users so there could be places to buy fuel that are not on the app. If you know of some you can add them to the app and future users will benefit.

 

[Hammerz]

No one has mentioned fitting divider plates in the TMX, I did this to my 300 and got a bit improvement in low end power. Bike pulls like a four stroke now, although I think the rekluse I installed at the same time helps spread the power also.

 

[Errk]

Another thing to make sure everyone dose is adding a 1.3 mm spacer to preload the power valve spring. Just make sure the spacers ID is the same as the shaft so it has no movement ( this system needs to remain balanced) this mod greatly improves mid range and completely eliminates bog before the powerband. It makes the power very linear and there is no hard hit just a smooth pull. Top end remains the same which for me is enough to make it hard to keep the front wheel down in every gear. The reason the 250s bog just before the power band is that the power valve is opening to early. The spring preload shim makes the power valve open a little later getting all the mid range back. I did this to my 2004 wr250 btw and wish I did it a long time ago. Yes you have to remove the case cover and drain your fluids but it is well worth it in my opinion

 

[mr_manny]

Another thing to make sure everyone dose is adding a 1.3 mm spacer to preload the power valve spring. Just make sure the spacers ID is the same as the shaft so it has no movement ( this system needs to remain balanced) this mod greatly improves mid range and completely eliminates bog before the powerband. It makes the power very linear and there is no hard hit just a smooth pull.

Is anyone familiar with this mod?
Currently have my power valve/jug apart, and would appreciate any additional information on this mod.

Cheers