Exhaust Gasket?

[Uzi9mm]

Recently had an exhaust leak.  Is the metal exhaust/crush gasket required?  I have an FMF Desert Gnarly.  I called FMF and they said no gasket is needed.  Just use the O-rings and some high temp silicone.  I was thinking of making a new gasket out of some exhaust gasket material from Napa but the new one will be 2x as thick as the stock metal gasket.  What does everyone recommend?

[GDubb]

I have wondered the same thing. I dont have a crush washer either and couldnt find one. I would think that as long as your pipe mounts still line up and you can stretch the exhaust springs to still fit then there would be no harm in a thicker gasket material and a better seal. My 2 cents.


-G

[Danger4u2]

The exhaust gasket is copper.  It's in there for wear.  With all the vibration the copper will wear instead of the end of the pipe and more important the cylinder where it mounts.  As far as a thicker home made gasket (should be copper)  just make sure the o-rings are still in far enough to seal.  I've never used silicone on my exhaust.  Something is worn out for it to leak.  O-rings, gasket, pipe end, springs, or cylinder.  The pipe mounts are where this usually starts.  The pipe mounts don't last long on my bike.  I'm getting ready to ride Little Sahara Okla. Monday and Tuesday.  When doing my pre ride and service check the mount under the tank is broken and the one by the cylinder is split and about to break.  Check your mounts, if they are bad it might be that your pipe moves around when you ride and that could be the cause of the leak.

[KX500freak]

The exhaust gasket is copper.  It's in there for wear.  With all the vibration the copper will wear instead of the end of the pipe and more important the cylinder where it mounts.  As far as a thicker home made gasket (should be copper)  just make sure the o-rings are still in far enough to seal.  I've never used silicone on my exhaust.  Something is worn out for it to leak.  O-rings, gasket, pipe end, springs, or cylinder.  The pipe mounts are where this usually starts.  The pipe mounts don't last long on my bike.  I'm getting ready to ride Little Sahara Okla. Monday and Tuesday.  When doing my pre ride and service check the mount under the tank is broken and the one by the cylinder is split and about to break.  Check your mounts, if they are bad it might be that your pipe moves around when you ride and that could be the cause of the leak.

im with danger ,
allways use one copper ringgasket.
and indeed the exhaust mounts are a week spot !
most important is to hang the complete pipe tension free in the mounts.
also the can must be mounted on without any use of force,

if there is  tension in the pipe the force goes through the mounts and they snap 
did this mount with my both k5s and never had a broken mount again

[Uzi9mm]

Thanks for the replies.    The pipe mount under the tank is starting to split, one of the o-rings on the pipe is torn, plus the copper gasket is crushed out of shape and torn.  I ordered a some mounts and some gaskets.  The mount under the tank needs to be shimmed out a little.  Anyone have any trouble with aftermarket pipes matching the mounts?   

[Danger4u2]

Yes, FMF Gnarly.  I shimmed also.  Like KX500freak said.

most important is to hang the complete pipe tension free in the mounts.

[Uzi9mm]

I need some advice.  I always thought my pipe was on a little crooked.  The amount of pipe around the cylinder looked uneven when i got the bike.  There was a ton of silicone around the pipe.  Theres been a small exhaust leak for a while.  I should have checked it out sooner but I was having fun riding.  When I bought the bike the top mount was torn.  I replaced/shimmed it and had to grind the pipe bracket because it was rubbing the tank.  I thought I had it all straightened until yesterday.  I pulled the pipe off cleaned and polished the pipe.  And cleaned the cylinder.  I tried the pipe on the bike with a 1/16 exhaust gasket and without.  I wanted to hang/shim the pipe so it would be tension free.  Both times, the pipe looked like it was designed for another bike.  Holding the pipe flat against the cylinder the pipe mounts were way off.  The mounts are so far off they cannot be shimmed.  I figured I needed the springs on to really pull the pipe down.  I put on the springs and o-rings etc..  With the springs on, I could see the pipe was evenly seated.  But no matter which way I rotated the pipe the mounts were still way off.  I could make it fit if I forced the pipe at an angle and bolted it up.  But there is a lot of tension on the mounts.  Would a pipe for another bike almost work on the 500?  Or, is this the way it is with aftermarket pipes?   

[KX500freak]

I need some advice.  I always thought my pipe was on a little crooked.  The amount of pipe around the cylinder looked uneven when i got the bike.  There was a ton of silicone around the pipe.  Theres been a small exhaust leak for a while.  I should have checked it out sooner but I was having fun riding.  When I bought the bike the top mount was torn.  I replaced/shimmed it and had to grind the pipe bracket because it was rubbing the tank.  I thought I had it all straightened until yesterday.  I pulled the pipe off cleaned and polished the pipe.  And cleaned the cylinder.  I tried the pipe on the bike with a 1/16 exhaust gasket and without.  I wanted to hang/shim the pipe so it would be tension free.  Both times, the pipe looked like it was designed for another bike.  Holding the pipe flat against the cylinder the pipe mounts were way off.  The mounts are so far off they cannot be shimmed.  I figured I needed the springs on to really pull the pipe down.  I put on the springs and o-rings etc..  With the springs on, I could see the pipe was evenly seated.  But no matter which way I rotated the pipe the mounts were still way off.  I could make it fit if I forced the pipe at an angle and bolted it up.  But there is a lot of tension on the mounts.  Would a pipe for another bike almost work on the 500?  Or, is this the way it is with aftermarket pipes?   

hey uzi9mm,

i can say a view things that can cause your issues with the pipe.
how old is your k5 ?
how is it been treated,

reason im asking is if that bike is 14 years old and heavely abused then the frame itselfs gets out of shape!
seems odd but it is true i did experience it myself with my former mxk5 when i got it.
that bike has been crashed severe in the past and that was noticable very clear after a view inspections.

2 out if 3 pipe mounts where snapped ..
tailpipe snapped..
also that f#ckin kit around the pipe..

it really did look like yours...never to fit again 
but i saw if i could get the tension out of it it would stay in one piece at least.

so my advise go check the perimeters of the frame and subframe,
see if its not bended in any way,
then if that is good looking ,that pipe if not bended itselfs ,should fit without major adjustments or use of force.
also linking the muffler must go without tension cuss if you tighten the bolts it gives in ,then use a shimp to keep it in its place while tightening the bolt

i did my pipe like that on this crash bike and its sitting there tight ,and no snapping mounts or leaking anymore.

suc6 with the struggle

[Uzi9mm]

The frame looks good except for a small dent under the left side of the engine, no skid plate.  The rear chain guide is a little scraped up.  The previous owner flipped it and cracked the back fender and scratched the silencer.  The plastics are a little scraped up.  Thats it.  I think the guy who had it before me was retarded.  For example, the bike came with Pro Taper bars.  The problem was that he cut the bars with a hacksaw and made a mess.  He cut through both grips and the throttle slider.  I replaced the bars, grips and slider.  Thats, why I was asking if someone could bolt up a pipe that belongs on another bike.  Because, if its possible the guy I bought this from probably did it.   

[KX500freak]

well i can say this ,
a pre 90 pipe is different then a 90 or more .
reason i have both pipes laying here and the angles are tighter on that pre 90 pipe
maybe the problem lies in there,
also did he flip that bike like my prevouis owner did too..
so bettercheck your sub frame really good ,when that took a hit,
it also causes pipe fitting issues

[Uzi9mm]

My bike is a 2002.  Its in good shape overall.  Heres a picture.  This pic still has the broken back fender.  You can see the blue zip ties just behind the seat.  This is after I replaced the bars, grips and throttle slider.  You can see the pipe looks nice.  Just doesnt fit.  Maybe, the guy trashed the previous pipe and made this one work. 

[Uzi9mm]

FMF suggested that the pipe is bent.  At this point, I am going to try a new pipe.  I wanted a Pro Circuit 2 anyway.

[serafin]

Definitely get  a new crush washer and new o-rings to start.  My experience with after market pipes is that they all need a little bit of tweaking.
Start by hanging the pipe loosely with the exhaust springs, then see how the mounts line up.  Sometimes you have to bend the mounting tabs on the pipe a little and/or you have to enlarge the hole a little.  On my pro circuit I had to shim out the lower mount (add a washer or 2 and use a longer bolt).  Hope this helps a bit.

Serafin

[awak100]

I agree with serafin.  Hang pipe with springs and start from front of pipe to rear bending tabs if needed,or shims.  By the way I'm makeing new style exhaust mounts/dampner if anyones interested, alot stronger.