What is this adapter piece on the stock header?

and what is the best way to remove it?

I picked up a WR250x that has an FMF Powercore 4 exhaust pipe with the quiet insert, but its still too loud for my taste. The guy I bought it from said the pipe was already on there when he got it and it had a different insert and he put the quiet in there and he still thought it was loud (he also repacked it) so he picked up a stock pipe, but said he couldn't get the pipe off to put the stock on there, so he gave up.

I finally got the FMF Powercore 4 off tonight and I see why he struggled. It looks like there was some sort of adapter piece used to attach the powercore exhaust to the stock header? So now this adapter piece which I don't think is stock is stuck on the stock header? I don't see how I can get it off without totally beating up the stock header?

Here was how it was put together:

This is the PowerCore 4 on the left which slid over this adapter piece which is slid over the stock header? Is that how that was supposed to be put together or did a Previous owner just totally rig that up? You can tell how far on the powercore was over the adapter and it took some mighty finese to get it off


The Powercore side of things is still fine and no issues there


Here is the adapter piece slid over the end of the stock header




It's actually a little past flush. I haven't found anything to even budge it yet? Maybe some heat would work? Haven't tried yet.






Here's the stock ehxaust which I think should just slide right over the stock header without that adapter piece on there?

I think it's a custom gasket. Maybe the PO didn't have the right one.

The stock header does have a ridge about 20-25mm up the tube where the mid pipe should slide up to or close to. Then the gasket in the exhaust makes the seal

Are you good with a zip cut? If careful you could slice the thing off. Just use patience.

I think I can shed light on your issue. Looks like the aluminum adapter that the FMF usually comes with was pressed on way too far onto the stock header & was badly deformed in the process. Looking at it closer, it may also be a home made piece that someone put on there. It should normally have slipped onto the end of the header & stopped at the lip & the FMF would slip onto it. Your header should still be the normal diameter underneath. The best way to remove that sleeve now would be to use a Dremel or die grinder with a cut-off wheel & carefully cut a groove in the sleeve down it's full length but not cut clear through, otherwise you risk cutting into the header. stop short of cutting through & then use a screwdriver & small hammer to split open the cut you just made & the sleeve should come off. The mesh gasket in the muffler should now fit snug onto the header.

sswrx wrote:

I think I can shed light on your issue. Looks like the aluminum adapter that the FMF usually comes with was pressed on way too far onto the stock header & was badly deformed in the process. Looking at it closer, it may also be a home made piece that someone put on there. It should normally have slipped onto the end of the header & stopped at the lip & the FMF would slip onto it. Your header should still be the normal diameter underneath. The best way to remove that sleeve now would be to use a Dremel or die grinder with a cut-off wheel & carefully cut a groove in the sleeve down it's full length but not cut clear through, otherwise you risk cutting into the header. stop short of cutting through & then use a screwdriver & small hammer to split open the cut you just made & the sleeve should come off. The mesh gasket in the muffler should now fit snug onto the header.

This. ^

Holy shit - how the hell did previous owner force that adapter piece that far up the stock header?????

Thanks guys. I did not think that was stock. I guess cutting it off would work.

Your guess is as good as mine as how he got that adapter piece so for on the stock header.

I found someone who offered up their stock header very reasonably, so I think I'm just going to purchase that.

i didn't use the FMF adapter....just the stock packing and the clamp off the exhaust....drill the spot weld attaching the clamp to the muffler and slip the stock packing onto the header...didn't have to cut the header or the FMF...