FMF powercore 4/2 modification??

1 reply to this topic
  • natediggity

Posted January 09, 2004 - 10:41 AM


Does anyone know if it is possible to drill out the end cap on a Powercore 4/2 muffler with a spark arrestor and replace it with a Q insert? FMF tells me that it will not work but I don't know if I believe that. The muffler housing is the same size, why would it not fit? Has anyone done this?

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  • oldbones

Posted January 09, 2004 - 03:36 PM


I have the Powercore IV and have had the unfortunate "pleasure" of having it all the way apart (end cap blew off, ended up repacking silencer). This pipe is basically a straight through perforated core surrounded by packing to absorb the pulses, thereby reducing the sound. There is no directional change taking place inside the muffler can. If you think the powercore IV is loud, try the same pipe with the end cap off, it will make your ears bleed. It was loud enough that I parked my bike in the middle of a race and finished on a team members bike that I had never ridden.

The Q pipe (I BELIEVE!) uses a different principle. It is not a straight shot through the silencer. The core takes a turn down near the end of the can, and dumps the exhaust towards the bottom of the endcap. The opening on the inside of the endcap starts up by the top of the can, and exits in the middle. I think the Q cap would hit the inner core of the PC IV.

Take you two hands and put them out in front of you. Touch your two index fingers, tip to tip, making a straight line across in front of your face. Thats the PC IV. Now take your left finger and point it down 45 degrees, and your right finger and point it up 45 degrees. That's the Q.

OK, all that being said, there is a caveat to my answer. I actually do believe it could be done. As long as the diameter and bolt pattern were the same (I don't know that one), then you could just remove a little bit of packing from the back end of the silencer, just on the top half. Then just cut away a tennie bit off the top of the inner core until the Q cap slid in without hitting the core, and VIOLA, there you have it.

But, would it "work"? I dunno. You might end up with some pretty turbulent flow in there and lose more power that going with a full Q pipe. Then again, because you ARE straightening the exhaust flow a little, you may actually come in somewhere between the two pipes before modification. Same goes for the sound level. I would be pretty sure it would be louder than the Q, and some degree quieter than the PC IV, but by how much :) who knows.

Is that a long winded enough answer for you?


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