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Posts: 18
Reply with quote  #1 
Here is what I got:
2008 Outlaw 525S - FMF Power Bomb - FMF Factory Full Titanium 4.1 - Stock air filter and box , 4 quarter size holes in lid , covered with 12 x 12 outerwears sheet. 

Starter Main Jet = 85

Main Jet (138) w/ Needle (B36)

Air screw 2 1/2 out

Has been backfiring on deceleration pretty bad , not just a little, but a lot. Other than that, the quad is a beast, and runs TOP.

Did some research over on the KTM forum and here  is what they did:


In summary , you order KTM OEM part # KTM EXHAUST FLANGE 03 (SXS02540506) $28 from motosport , my fmf header pipe had some slight deformities and wasn't 100% round, so I went to Harbor Freight and purchased http://www.harborfreight.com/small-tail-pipe-expander-69550-9156.html ( small tail pipe extender) Add a little grease to it.

Using this, it opened the tip of pipe slightly so I could get the flange in (tight fit), using a rubber mallet I was slowly able to get the flange it, not all of the way, but tight, added some red gasket stuff to that connection for insurance, and let it sit for a day.

Next when I installed the head pipe , I made sure not to move it around from the muffler end of the pipe, as to not pull the flange off center. Bolted the flange , added new heavy heavy springs from home depot ( Century Spring C-173 , paid .99 for two in a pack on clearance.

Once done , I carefully installed muffler, making sure not to move the head pipe connection. added a slight bit more RVT . Let sit overnight. Everything is solid, no movement at all.

Next day, fired it up, once warm , got on it !! Pop gone !! No backfiring at all , finally .....

Went for a trail ride , still success :-)

Let me know if you have any questions, hope this help someone..

2008 Polaris Outlaw 525S - FMF Titanium Full 4.1 - Tusk Fat Bars - ODI Grips -

Posts: 1,674
Reply with quote  #2 
The outlaws (and RFS quads/bikes) seem to all have the same issue with the air leaks at the flange causing de-accel pop.  On mine, I took the head pipe and flange to a local muffler shop and they welded them together and fixed the leak for $20.00.   Ive done it to 2 exhausts and so far no problems. 
2007 Outlaw IRS

"Outlaws are the Chuck Norris of the quad world."

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Posts: 8
Reply with quote  #3 
for mine, i went to local auto parts and got exhaust pipe patch putty, took the header pipe off, wire brushed where the flange and pipes touch, put the patch putty in there, put it back together...no more back fires.....
2008 Outlaw 525 irs,,,2006 Trail Boss 330,,,2003 Predator 500
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