2007 WR450f FMF muffler?

Putting a FMF on my 450 do you use the band clamp or just silicone?

Just went through this a couple of months ago with a PowerCore...

I was told it was a slip on (which it is) and no silicone was needed...

Trust me, just get some high temp silcone and you'll be rockin! use the right coupler depending on the header and no need for the clamp. :thumbsup:

I didnt have silicone on hand when I installed my Powercore. Do you think it makes that much of a difference? If so I suppose I could pull it off and put some on pretty easy.

naa makes no difference, you might get a little popping when you let off the gas from air getting into your exhaust but performance wise I dont think it makes any real difference...

I put one on my '07 when I first got it (never rode it with the stock muffler). I didn't use any silicone and have never had any issues with decel popping. Did the JDJetting as well.:thumbsup:

I guess I wont worry about it then. Thanks TT

They can already be a pain in the ass to slip off and on, I would strongly suggest NOT putting any sealer in there and no clamp is required...

I have a Q2 and Power Bomb on my 07' since day one, no clamp or sealer and there is dents all up and down the system but the pipe to header connection has never leaked :thumbsup:

I had it without silicone for a couple of months until I added the silicone.

Makes a difference! started getting more decel popping as the temps dropped this fall (messed around with jetting trying to get rid of it) and when I added the silicone it sealed it right up, runs smoother and better with the silicone. Even FMF suggests using it for optimum results.

I'd say for the few dollars for the silicone, what do you have to lose? The slip on set-up does not seal up like the stock pipe does with the clamp. I'm sure some bikes will seal better than others but if you haven't tried to seal it with silicone...you really owe it to yourself to try it, I was surprised of the difference, and I thought it ran good before.

Ya know I have had more decel popping lately with cooler temps. Ahh what the hell you talked me into it. Guess Im getting some silicone. What is the cheapest place to buy some anyway?

problem is if you use that junk odds are youll get it leaking into the exhaust chamber... once it gets hot it kinda melts and then flies back and cloggs your spark arrestor (if your running one) up to you...

Ya know I have had more decel popping lately with cooler temps. Ahh what the hell you talked me into it. Guess Im getting some silicone. What is the cheapest place to buy some anyway?

Not sure if you already got it but, just head to any auto parts store and they will have high temp silicone. Good luck!

You think this could happen even with high temp silicone?

I've used high temp silicon as per the instructions (http://www.fmfracing.com/RiderSupport/RepackingInstructions) that came with my slip-on 4.1 for years and haven't had a problem with either leaking or getting it off - just give it an easy twist and it slides off. DON'T use exhaust cement. you will definitely have problems getting your slip-on off if you use that gunk.

I think the fit is a bit tighter/better if you're using a FMF header as well, as opposed to the adapter colar that comes with the slip-on, so in that case it might not be as necessary to use silicon. Just my two cents.

tt newbee here!!!! ruderacer87 got a 07 wr450f with the same fmf muffler and stock header. stock jetting and opened air box...do i need to do jet changes...im in california from sea level to 5000 ft....thanks anyone

Edited by ruderacer87

Search tool is your friend!! Good luck! and WELCOME TO TT!!

tt newbee here!!!! ruderacer87 got a 07 wr450f with the same fmf muffler and stock header. stock jetting and opened air box...do i need to do jet changes...im in california from sea level to 5000 ft....thanks anyone

Definatley should re-jet:thumbsup:

http://www.thumpertalk.com/forum/showthread.php?t=411240

I have the FMF megabomb and a LEXX MX slip on; this weekend the adapter collar, which was never really seated properly, slipped out all the way and I noticed the leak from the obvious increase in sound and the heat. I could not get that adapter back in place, is there a trick or is the suggestion to do away with the adapter and run silicone? I cannot be the only one out there that does not want to have the noise from the gap thats left when you slip the lexx onto the megabomb.

any and all constructive input is appreciated.

figured it out.....took the exhaust apart and slipped the collar adapter in, then put that slowly onto the header - perfect! and no silicone

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now