fmf exhaust

pukesucker

New Member
Apr 7, 2011
3
0
17
i just rebuilt the top end of a blaster and it has an fmf header pipe that is flanged out so it is loose and leaking. i cant find a exhaust clamp that is made for it so before i try to just find one that fits and clamp it- is there any suggestions on how to make it not leak. i see a spot for a spring on the pipe but there is no spot on the blaster for one. even then the spring would snug it up tighter but it would still be lease and might leak. also i notice it wants to rev and or stay revved high- is that from possible air leaks causing it run rev and run lean? what is an exceptable operating temperature?
 
if it's reving it's lean proly an air leak. fix before running,

there should be a loop on the flange for a spring.

never checked temp so I don't know
 
FMF only has one spring. The spring mount is missing from my flange. The previous owner ran a spring to a spot on the head. I bought a new replacement flange from a member here and was disappointed when I got cause it was missing the spring loop also.
 
I have used a tailpipe spreader to aiid in the leaking, but stil needed to use some copper RTV to seal my power pros flange.
 
No matter what you are always going to leak where the pipe connects to the flange, or atleast in that area.

I respectfully disagree with this statement.

My stock pipe spewed some sludge all over the front of my motor. But I cleaned it all up, installed my FMF flange & pipe using the copper RTV, and I've got zero leaks after 6 months of riding.

Here's my approach:

1). I installed the stock exhaust gastket ring in the head
2). I put a small bead of copper RTV all the way around the face of the flange (where it meets the head) and installed the flange to the head.
3). I put a fat bead of the RTV on the top of the flange (where it goes into the pipe).
4). And for good measure I put a bead around the inside of the pipe (where it mates up to the top of the flange), followed by installing the pipe on the flange and connecting the spring.

Good luck!
 
I respectfully disagree with this statement.

My stock pipe spewed some sludge all over the front of my motor. But I cleaned it all up, installed my FMF flange & pipe using the copper RTV, and I've got zero leaks after 6 months of riding.

I'm pretty sure he was talking if you just bolted up and gone with it not taking any extra steps to seal it up