Preliminary Pipe Report

Pipe and more pipes.

I ran the complete Stroker REV System on my YZ WR 400. NOTE since I have the Titantium YZ subframe on my WR I must use the YZ Stroker parts the Stroker WR tail section will not bolt up to a YZ subframe. I Spent a day at Stroker in Hisperia getting all this sorted out, after a couple of attempts at home to mount a WR tail section it was obviously a nogo.

The REV System headpipe and tail section fit and finish were excellent. This is Strokers REV oriented system with a huge diameter step taper head pipe. The Head Pipe starts out at a whopping 42mm ID!!!! can you say minimum low end!!! The pipe was quieter than the FMF PC-IV-2 and with the quiet tip in place I think is was easily under 99dB, but not actually measured. The Stroker REV system is a strong mid range system works great on fire roads and open stuff. Would probably be outstanding in drag races. The REV System is a little soft on the bottom and not as suitable for tight slow speed stuff as the FMF PC IV-2 which had outstanding low to mid power but was a little soft on top. Same everything: the PCIV-2 topped out at about 85-86, the Stroker REV System 90 and the WB Promeg with 15 disks 92. Of course the Pro meg with 15 disks is totally too loud for trail use the PCIV-2 a little quieter and the Stroker OK.

I then ran the Stroker REV system with a WB torque valve installed it helped the the low end a little but killed top end, the mid was still strong.

I then adapted my WB tapered head pipe to run with the Stroker tail section and it ran much better in the low to mid outstanding mid and good top end. This is a very usable combination for all situations and is reasonable quiet. I'm banking that the low end will improve more with the Power Bomb header and even with the stock header. I did not at this time want to mess around with the stock exhaust sealing gasket since once inatalled its tough to get out without damage and the thing cost $15. So after I get the power bomb I will evaluate the Stroker Tail section with the stock header and the Power Bomb header. Probably will not get to this for a while.

When I get the Power Bomb header I have a feeling this header and the PCIV-2 will be excellent on the bottom end / mid and be outstanding for trail use the only question is will it be even close to reasonable in the quiet department????? If not I'm hoping the Power Bomb will further pick up the bottom end response when used with the Stroker tail section and perhaps even quiet things down more.

More to follow after I complete this series of tests.


Hey Clarke!

Couple of questions;

1. With the Carbon E-Series would you want the s-bend or tapered for overall power?

2. How does the E-series with the quiet core stack up noise wise.

3. You said you thought that the power bomb (when it comes out) combined with the PCIV-2 would be the way to go, folloedw by the Stroker tail section. What about the E-series and the power bomb?

4. I like alot of other people on this site are anxiously awaiting your evaluation of the power bomb when its available, but in the mean time could you suggest a baffle Vortip, Baja Baffle, Stroker or Thumper?

Thanks for your time!


I run my e-series Pro-meg with a tapered headpipe and it works great its just too loud. The tapered head pipe helps low to mid and the Pro-meg helps on top. For open riding I like it, but I ride out of my garage a lot and I feel guilty riding in Valencia with this pipe-loud. I would imagin the S bend would pull better down low and make a better trail set up.

As to the other combs of head pipes and tail sections will have to wait for more testing.

I you ride loud and proud I feel based on my testing and what I read that the Yoshimura race pipe, DSP, white Brothers e-seris are all excellent. Sounds like the Big Gun SDS is also a torque pipe an is a little quieter.

I probably will end up with two pipes one for known sound test areas and one for everywhere else. Haven't maid my mind up yet and wont until I test the power bomb.

So far I still think the FMF Mega Max II was the most flexible and tunable of all for quiet and still trail and dual sport rideable, but not as flashy or as quick through the power band as the Yosh, WB or DSP.

Remember I'm looking for a compromise its obvious that to get the best and max power its going to be loud, and I want reasonable rideable power for trails / dual sport without the noise and some weight savings. Luckily all of these pipes are ligher than the stock boat anchor.


JJ,, The E series with the quiet core will knock off about 4 db's. My bike sounded off at 107 with 12 disks, went down to 103 after the insert of the quiet core. Helped but not enough. Finally got it down to 101 db's with 7 disks. That is what the ranger in my area wants. The quiet core with 12 disks did not hamper my power much. I thought it did at first, however after timing on the laps I had no decreases in time, thus I think I felt slower due to the noise, however I think the speed was still there. Did lose a little on the bottom however. 7 Disks did decrease the power some. Still working on the jetting side, so if anyone has any ideas please let me know. My hope is the power bomb, with the E series and the quiet core will get me to the 90's. We can only hope at this point. It is frustrating.



98WR White Bros E Series stock head pipe, IMS Tank/seat Pro Tapers Works Connection guards. Stock timing

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