FMF powercore 4 on stock header ?

7 replies to this topic
  • roadhor

Posted April 26, 2004 - 07:47 AM


I just picked up an FMF powercore 4 off ebay for a song, but when I tried to mount it up to my stock header it fits too loose to clamp up, but isn't big enough to get the factory exhaust gasket on . :D Is there a spacer or gasket I need to get from FMF or should I just hold off until I can buy an FMF header? Thanks for the help guys , Rob :)

  • cowboyona426

Posted April 26, 2004 - 08:09 AM


When I had my Powercore IV, I just slipped it on and tightened the clamp as tight as it would go. I never had any problems :)

  • mmbasa

Posted April 26, 2004 - 08:53 AM


I just slipped it on and clamped it down. No gasket needed. If you want you can get some gasket maker from the auto parts but not really needed.

  • benny_d

Posted April 26, 2004 - 08:53 AM


I got one off of Ebay as well a couple years back. It came with a metal shim. I don't think mine will tighten without that.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • TonyDeCoster

Posted April 26, 2004 - 09:11 AM


I used my old gasket from the original pipe. The previous owner may have installed it without a gasket. You can use a muffler expander to get it back to the correct size. Make sure you expand it large enough to fit the gasket in. I've had good luck with muffler shops doing this forfree... :)

  • roadhor

Posted April 27, 2004 - 06:50 PM


Thanks for the help guys , but mine will not tighten down all the way, the header is just too small. "The story of my life!" I may just wait til I can afford to get a powerbomb header. Thanks, Ro :thumbsup:b

  • groundhog

Posted April 27, 2004 - 11:16 PM


Hey Roadhor,
I had the same problem with a used PC4. I got a sheet of exhaust gasket material from the auto parts. Just the right thickness. Then I used a piece of "plumbers tape" metal hanger stuff and made a shim between the stock clamp and the pipe.
But here's the bite. I got a power bomb last week. It doesn't fit either. In fact it seems like it is a bit too long besides being too little in diameter. After many phone calls to FMF it seems that the early PC4s are a little different than the newer ones (no sh*t).
Just got my NEW PC4 last night. Haven't had a chance to put it on, but it looks like it will fit better. The header end is necked down. Will probably have to get a different clamp though.
If I have any other problems with the new PC4 (installing) I'll let you know.

  • groundhog

Posted April 28, 2004 - 04:58 AM


I got the new PowerCore 4 mounted. Fits fine, no gaskets or modifications. They sent a new clamp and all hardware.
The old PowerCore has a number stamped in the mounting bracket closest to the header Y-411B. Like I said before I had to use gasket material between the header and muffler as well as 2 wraps of plumbers tape under the clamp (stock header). That worked fine for 2 years.
Hope this helps a little.

Related Content


Megabomb Fitment by 288yz450

Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • 1 reply


Dirt Bike   Make / Model Specific   Yamaha   YZ 400/426/450
  • Hot  30 replies

Snake pit oct 30th by The Anvil

Dirt Bike   Dirt Bike Regional Discussion   California
  • Hot  293 replies

Yamaha YZ450F 2017 by Chris.GVS

Yamaha YZ450F 2017
  • * * * * *
  • 1 review
  • Last review by Tommyk_55
  • On January 15, 2017

The "going back to the other darkside" adventure... by Monk

Dirt Bike   Make / Model Specific   KTM   250/350/450/505 SX-F & XC-F (4-Strokes)
  • Hot  113 replies

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.