white bros. "tork" vavle insert

:) WOW that certainly is technical, cant argue with a flow bench....BUT....as stated, by the seat of the pants, more bottom, no effect on top, which one do we use more????

I'm not saying that on a dyno/flowbench you wouldn't see a diff at the top, it is just not appreciable :D

I have the full WB E Series exhaust. Should I purchase this from WB or some other source?

Is there a link someone can provide for an Internet purchase.

Hey Kevin, can you say "Bulk Buy" :)


Awesome thread guys.. little bashing!! I used the valve with a fmf powercore 4 and noticed very little change. This makes sense because the powercore is a bottom and mid rpm pipe. ( the pipe design had alread maximized the flow restriction idea)

Now I have a stock yz exhaust and haven't tried the valve. I have to figure that to gain something you will loose something. Since I am interested in top end power, I am thinking that I will loose top end. Also it is so hard to tell how much you are loosing. unless you try top speed up a hill or you are racing someone. Percieved power is so much different than real power. I would sure like to get better mid punch but the first time my buddies modified 660 xr beat me in a drag, things would have to change!!

with torx valve installed there is massive increase bottom end,decent increase in mid range torque[front tire comes up with less effort]i have felt no loss in top end.if anything there was slight gain in top end performance.i dont care what mumbo jumbo dyno results show.dyno testing is a nonsense [every dirt mag that ran exhaust dyno test showed stock yz exhaust out performing all the aftermarket silencers.]the performance results im giving are from 6 months rode testing.

:) I'm pleased its not just me who thinks it works well, Freestyle's feeling are the same as mine, and we have fitted the thing's and run them, mine has been in about the same time as "F"'s.

When you actually see the thing, you appreciate the R&D WB put into it, it is NOT simply a plate to restrict the opening, in actual fact it is an insert to re-shape the opening, and where as the hard facts of a flow bench MAY show a decrease in flow at high RPM, the on board diagnostics, show no problems at all.

WB are not noted for their B.S. and their "Bumph" quotes a 1 BHP increase accross the range, whilst 1 full BHP may be optomistic, there certainly is a noticable boost to the bottom and mid,

And for those who still ponder the top end, I can hit the Rev Limiter in top with an indicated 110mph(on the speedo)

Just my 50cents worth....(long post LOL) :D

Does the insert make the engine run hotter due to increased backpressure or is the exhaust flow enhanced by the insert and let the engine run cooler or the same as stock? Thanks for any info on this product---WR Dave.

i havent noticed any overheating since installing tork valve.here are some pics tork.JPG

Thanks everyone for the wealth of info and genuine heart felt opinions. I put mine in and rode this weekend in some of the toughest single track that is close by. Roots, sand, clay, rocks, rain induced ruts & hills. I felt the low end was an improvement as well. I was allowed (except for one hill) to stay in second gear for everything and ride smoother through the nasty stuff...pulls third a little better as well.

In addition I was able to go from 5 discs to 8 with a noticable improvement in mid & top end. Overall I'm happy with the way the bike feels now. Very good investment. No increased heat.

I do notice a little more of a tendancy to hick up if I open the throttle suddenly at low RPM, which I rarely (never) do...in fact I even got the bike to cough and die once...which has never happened. I adjusted the koboda air tool out 2.5 turns or so and it did seem to help a little.

As far as the valve itself, I would agree the front end is easier to bring up. Racing my brother's 426 however, I was a few bike lengths behind after the mod, which would lead me to believe it may rob a little power up top. Despite all the hype over the 426, we're typically pretty even in a drag race, however the 426 pulls considerably harder off the bottom.

I guess I just wanted a little of that...any other sauggestions out there to give the 400 a little more bark of the bottom??


A 2mm larger piston works wonders for adding low end power.

count me in if we do a group buy!!

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