FMF exhaust question for xr650r

3 replies to this topic
  • 2000 xr650r

Posted December 11, 2005 - 09:26 AM


I own a 2000 Honda xr650r with the stock header and a fmf powercore IV muffler. I am thinking about upgrading the header to a FMF high-flow stainless steel header, not the power bomb. Does anyone have experience with this header? Will this increase performance a noticeable amount. Do I have any better options?

  • khelton

Posted December 11, 2005 - 04:04 PM


FMF works great on my 2002

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  • strippedthread1

Posted December 11, 2005 - 04:25 PM


I have the powercore 4 with the power bomb header and love it. good sound, not much different in volume compared to the stock uncorked pipe.

  • BWB63

Posted December 11, 2005 - 05:26 PM


I hear so many back east say they never get out of second on the
muddy, tight, tree infested trails. The stock header is key here and
an open header would take away from the power of the bike for this
type of work. So, the stock header is more (of the right power in
the right place) then an open header. That is more power. It's
the, "where the power comes on" and "how" that is what the header

Some of the guys will state fact, only relitive to their type of
riding. Like I said, for most of the open desert riding more
horsepower moved up in the RPM range is more usefull. You will miss
the low grunt fast in the tight rocks, so, a pumper carburetor helps
but, won't bring it all back. You have to stay on it, and rev the
bike sooner or go 680cc and have the best of both worlds. There are
better riders out there that I will smoke in the open desert just
because I have a 680cc bike, better suspension and have little
common sense. If I don't crash they don't have a chance on a stock
bike. So, this 90% rider, 5% bike is not even a little true in this
respect. Take me to Maine, Georgia on my 680cc bike and someones back yard and
give him his little KTM and I will be lost wondering where did he
go??? It isn't all about bigger peak horsepower....(I have said this
many times) but, where the horsepower comes on and how long it
stays. The stock header realy allows the power to come on at the
very bottom. Right at 1200rpm's but, it gets a little lazy after
5,200 and falls off fast. Lets say, 44hp is peak horsepower for this
bike. Add just a header and peak horsepower will only be 46hp. Does
not sound like much but, stock bike #1 has only 40hp at 6,000rpm
while stock bike #2 still has 44hp. At 7,200rpm stock bike #1 is
down to 36~38hp and stock bike #2 is at 42hp and will hold that to
the rev limiter, while bike #1 will lose more to the end. It's all
about that choker in the stock header. It's there to give that
bottom end punch. You go to an after market, free flowing header and
you will lose that but, you gain a lot higher up.
David Gray and I were throwing terraferma up a steap hill.....very
steap. It had flour like dirt mid way up to the top. I was pulling
bottom to top in third and had enough left to jump off the lip off
the top, if all went right (many times nothing goes right) He would
hit mid RPM's lose power, sink and down shift, now it was all over
from there. The header made the difference. If it was rocky or hard
so the bike didn't sink oe some steap hill with traction, lugging it t the top then his header would have been better. He
now has that header of mine and knows the difference.

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