white bros. "tork" vavle insert

have you tried it yet?i recently purchased it and it was best $30 ive ever spent.you wont believe the difference in power it makes off the bottom.i highly recommend everyone try it.i spent over $400 on white bros e-series promeg and tapered headpipe and for $30 the torx valve makes just as much if not more of a performance increase.

Being ignant, where does this valve go (in the pipe)?

If it increases back pressure, will effect your top end?

I love bottom end, but a giant surge n the middle/top is always exhilerating!

Isn't that what Doug Henry had on his 98 YZ when he won the Championship?

its looks like a little velocity stack and it slides in end of headpipe on the exhaust port end.

Do you have a link to get this part. I looked on the white bros. web site and there is no such part. THANX! ~Hitman~

Originally posted by freestyle111:

hey kevin if backpressure gives more top end why do wr's go faster and rev higher when stock muffler plug is removed.i think you might of skipped 1 or 2 pages when you read your copy of "newbies motorcycle handbook.

I must have missed that chapter too, because my YZ revs better with the stock silencer than it did with the louder, more open T4.

i scanned packaging torx came in,it has part # i posted the photo with some wr400 parts im selling in my yahoo photoalbum [

[ June 05, 2002: Message edited by: freestyle111 ]

:) I got one from Santa!, Used it for the first time yesterday and there is a noticable difference from stock, A good cheap investment, all you do is fit it in the header, no welding machining, or messin' about!

A good cheap mod, worth the money! :D

> backpressure [generally] = > bottom end

< backpressure [generally] = > revs/ > top end

More specifically, torque is the ability for the header to scavange burnt fuel from the cylinder and RPM is related to how much total air flow you can get out of the pipe.



:) All the bumph which comes with it reckons than it's venturi shape scavenges the cylinder better at low rpm, but does not affect the top,

Yesterday was so cold and frozen that we were nowhere near WOT at all but there was a def increase in bottom end and no noticable detriment to the top....YET! :D

I have installed these on several H-D's and ran them on a dyno. They work better on systems where exhaust reversion is a problem (straight pipes). This however comes at a price. Making better mid range torque/HP by reducing reversion and increasing back pressure. but reducing flow so the top end HP numbers suffer. Well tuned exhausts showed no improvement or lost power. This is on a H-D. I am assuming that similar results would show with most 4-strokes. This will also make the bike feel like it is revving out better. Making more mid range power the engine will get to say 6,000 rpm faster but then from there up start to fall off because of reduced exhaust flow that it needs. Bottom line is where do you want the power. Most of us are usually from 2700-7000rpm 90% and 7000 and up 10% so the gained bottom-mid would be worth the few ponies lost at top. IMHO


Freestyle ,check your private messages.

I've also used them with a substial seat-of-the-pants increase in low end with no noticeable decrease in top end, with either a stock exhaust or an aftermarket pipe. This is all by feel with no dyno numbers. No question, it's a good $30 investment.

Would it help in a FMF power bomb header????

Hey Freestyle 000,

I overlooked your personal slam on the newbie handbook thing.

It is OK. I wrote the newbie book back when I was a newbie. This was back in 1972 when I started wrenching on bikes, cars & sleds!!

You completely misunderstood what I stated on back pressure vs. torque relationships!

I'll overlook your slam, THIS ONE TIME! :)

BTW, no Kouba for you! :D

[ January 01, 2002: Message edited by: NH Kevin ]


I just purchased one today and would like to know what I can expect as far as any jetting issues etc...I'm running a WR e-series with 5 discs and would like to increase bottom end power. Install sounds simple...just drop it into the header up close to the jug right??

In order to get me geeked for the weekend...please tell me one more time about all the tremendous low end power increase!!

Did you guys experience any problems with the top end?? Did you need to add any more discs to compensate??



:) It fits right at the end of the header, next to the cylinder, it fits in ONE place, no problems, The only issue I have heard about is that if the weld on the inside of your pipe is proud, you may have to grind the pipe a touch to seat it properly, I didn't have to do, it mine dropped straight in! :D

NO re-jetting

NO more discs

Just fit and GOOooooooooo! :D

and yes, seat of the pants dyno says, the bottom is better, without top end loss :D



This is an overview of how the ex. port size effects torque at the expense of peak hp.

The torx valve is a way to increase your bottom end but it does have an effect on peak delivery.

Just my 2 cents.

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