I wat to wake up my '07 WR...

9 replies to this topic
  • BigBelly

Posted November 22, 2011 - 04:44 PM


I bought this bike new in '07 and it's been flawless. I have done all the free mods and just last ride put on a 51 tooth rear sprocket. The sprocket gave it a little more bite but I want to wake her up a bit more. A full pipe is often recommended but I have recently been told about a "power now valve". Any of you guys running this on an '07? I don't want to tear into the motor, piston, cam etc. Just small changes. Any recommendations? I have gone back and read the FAQ and older archived stuff, just wondering if anyone is doing anything different these days...

Thanks guys.

Edited by BigBelly, November 22, 2011 - 05:01 PM.

  • mongial

Posted November 22, 2011 - 04:59 PM


I know you don't want to tear into the motor but the yz cams seem like the cheapest and best bet to me. I have an 09 with a full aftermarket exhaust system and the only real difference I can feel is the noise. Can't tell you about the power now but seems kinda of "gimmicky" to me.

  • BigBelly

Posted November 22, 2011 - 05:01 PM


That was my thought too but I truly have no idea. I am surprised to hear that your full exhaust system didn't do much but increase volume. Bummer... What did you put on it

  • William1

Posted November 22, 2011 - 05:08 PM


'PowerNow' is a carb insert. It will kill the top end (effectively reduces the carb size). It is designed for people who do not bother to get the jetting right.

The best thing you can do to the bike is cams. Most pipes will steal power from mid throttle and give it back at WOT. Some pipes do aid lower in the throttle range but all pipes do so with additional noise. You can get more with cams.

  • mongial

Posted November 22, 2011 - 05:16 PM


"What did you put on it"
I bought a NIB left over stock two brothers exhaust sytem off of FLEABAY for $100 shipped. The price was right. The bends in the header are not identical to the stock but the diameter is the same as the YZ. I am currently modding an OEM WR silencer to fit the header in order to drop some dB.

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  • YZEtc

Posted November 22, 2011 - 05:25 PM


FMF Powerbomb head pipe and FMF Q4 muffler.
More power everywhere, especially low end to midrange.
A little louder than the stock (which is quite choked-up) muffler and header, but completely acceptable.
I don't get off on riding loud bikes, and I wouldn't be using this system for two years if it were loud.

  • mongial

Posted November 22, 2011 - 05:35 PM


Best case scenario, the FMF system you describe will run at least $500. Anyone know off hand how much a set of YZ cams cost and the time to install?

  • William1

Posted November 22, 2011 - 05:45 PM


Depends on the source of the cams. I bet you could find a set used on ebay for $100. Install is about an hour or less. Tank off, valve cover off, spark plug out, timing plug removed, Engine set to TDC on Compression stroke, cam chain tensioner backed off, cam caps removed (watch for the c clip!!), old cams out, new cams in. Very carefully reinstall the cam caps, confirm the valve clearences are still good, release the tentioner, confirm cam timing, rotate engine very slowlytwo complete revolutions, confim the cam timing again, valve cover on, spark plug in and fuel tank on.

  • MANIAC998

Posted November 23, 2011 - 04:20 AM


Back in '01/'02 the carb bell was removeable on the 426, so I built my own Power Now carb insert. It didn't "Kill" the top-end at all, and what it did for the bottom end was incredible! It made it "snappy" off the bottom, like clutching it out of a corner. Your results may vary. Maniac

  • Summit

Posted November 24, 2011 - 10:48 AM


Definitely get a pipe.


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