WR450 & Thunder Alley Pipe

7 replies to this topic
  • Indy_WR450

Posted March 24, 2003 - 01:43 PM


Just ordered the Thunder Alley pipe with ceramic coating and spark arrestor for the WR450. Should have it 4 weeks. Bob Murray at Thunder Alley says his pipe works well with YZ or WR cam timing. The guys over on the YZ forum swear by them. Seems to be designed for a huge bottom end to mid rev range power increase with no gains up top. Has anyone on this forum got a Thunder Alley pipe on their WR450/426/400? Feedback please.

  • slomo138

Posted March 24, 2003 - 04:52 PM


I got my pipe last week.Very happy with looks and quality.
Put it on saturday,also opened up air box and changed main to what Bob suggested. I also dropped clip one position to #5. Sunday went to ride ,bike would not idle without choke. many jet changes finally ended up with a 170 main,65 pilot stock needle at #5,air screw at 1 3/4.Bike seemed to run pretty clean at these settings ,a little back fire at deceleration and a little bog on hard acceleration.Any suggestions would be a great help.
So far the pipe seem to do what it was meant to.
Looks great ,much lighter,fits almost as good as stock pipe
and so far seems to run stronger off bottom and rev quicker.Can't what to get jetting right and really see.

  • Indy_WR450

Posted March 24, 2003 - 05:26 PM


Try a YZ needle. I found the bike ran better with the stock pipe and baffle this way.

  • 450yjoffroad94

Posted March 29, 2003 - 11:31 PM


indy got the needle you said but man it is rich blowing black at rev up 48 piliot ndjn yz needle 165 main needle in 5 pos way to rich Help....... 744 feet

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  • 450yjoffroad94

Posted March 29, 2003 - 11:32 PM


P.s. Got big gun exhaust system

  • Indy_WR450

Posted March 30, 2003 - 02:32 AM


I sent you a PM, but my jetting works for the baha baffle stock muffler with a large air box cut out between the snorkel intake and the rear fender. The exhaust and intake mods will play a large roll in your needle and jet selections. You can try the stock needle to see if that is a better starting point for your needle selection.

  • gloft

Posted March 31, 2003 - 04:27 AM


Hey Indy,

How do you like your Baja baffle? I just ordered one instead of replacing entire exhaust with a FMF ti. Thought I'd see how this works first. I know the engine freed up a lot when I removed the stock baffle. Anyone else using the FMF TI?

  • Indy_WR450

Posted March 31, 2003 - 07:16 PM


The Baha baffle is very good and quiet. Latest mags tested it at 94.5 db at 4250 rpm (Dirt Rider magazine). I ordered the slip on Thunder Alley so I can switch back and forth depending on where I am riding. The Baha baffle does choke off the top end but the bike is still very fast.


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