2009 YZ450F: Stupid exhaust question

4 replies to this topic
  • husky390or

Posted September 02, 2010 - 07:27 PM


I have an 09 YZ450f and so far am having one helluva time getting an aftermarket slip on to work on it. I've already had to return one pipe from a different manufacturer and now I purchased an FMF Q4. Everything bolts up fine except the stock exhaust clamp is too big to clamp down on the silencer and the header. Both of the inserts that FMF sent do not fit on my header and the pipe as itself slips right on. Am I a moron and overlooking something simple?
I know the stock pipe has an insert that fits snugly over the header which gives the stock pipe a larger O.D.

Has anyone else had this issue? Did you get another clamp and from where?

  • crf450319

Posted September 02, 2010 - 07:51 PM



I took my stock exhaust off and bought 2 different headers on E-bay, one was an FMF and the other was straight out of China. I've got a Pro Circiut slip-on, but I don't know what year it's supposed to fit. Anyway, here's what I did.

I had a stock header from an '06 on my bike at first, crashed and bent the crap out of it (I'll never buy Ti again). I put my stock system on while I waited for my other headers to show up - I HATE the stock pipe !

So, I got impatient and took the junk '09 shorty off. Then I took my PC slip-on and my '09 OEM header to a muffler shop. The mid-pipe on the PC is stainless and too small of a diameter to fit over the OEM header. I had the guys at the muffler shop expand the last 2" or so, just enough to fit onto the stock header.

Then when the FMF header showed up I took my disc grinder out and put a little slit into the PC mid-pipe, then put it on the FMF header and tightened a hose clamp around it. I went back to the muffler shop and had them put a bead of weld on the mid-pipe where the cut had been - at that point it was closed as a result of having the hose clamp on it.

I've got 30 hours on the PC slip-on & FMF header now and haven't had any issues with it. If the stock system didn't suck as bad as it does, I would have left it on and would have left it alone. I've got 3 full exhaust systems for my bike now, one of them is the stocker - I'll never ride the bike with that pipe on again.

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  • Steel Panther

Posted September 02, 2010 - 09:38 PM


Im not certain about the slip ons, but on my fmf full system all just slips together, no spacers, no clamps, just some silicone. Also, I believe the inserts are for older models as the head diameter just got bigger over the years. To compensate they made the midpipes bigger and included a spacer to fit on the older smaller headers so they can sell the same product to different year bikes. So if the mid pipe just slips onto the header you should be good with just some hi temp silicone on the junction.

  • husky390or

Posted September 03, 2010 - 07:56 PM


Problem solved. I'm a moron. Thanks for the info guy's.

  • 02WR426Cali

Posted September 03, 2010 - 08:03 PM


Hey if you really want to put a clamp on it take it off and cut slots in the end of the slip on where the clamp goes. The stock one most likely has slots like I'm talking about. The slots allow the clamp to work and let it squeeze together. That's what I did on my Q4 I put on my 426, I cut the slots and used silicone AND a clamp. Much better to have a clamp in my opinion.

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