Exhaust leak between header & silencer

[Bkicker]

Where my stock header connects to fmf powercore 4 silencer I have a substantial exhaust leak. How and with what would you recommend sealing/fixing it

[NoFiddyPilot]

Per the FMF install instructions:

 If installing the FMF muffler onto a stock header, you will need to use the supplied aluminum reducer sleeve in the midpipe (front) inlet.  Apply a light bead of high temp silicone to the outer edge and insert into the midpipe. If installing the FMF muffler onto an FMF header, the supplied aluminum reducer sleeve is not used. Loosen the header flange hardware at the exhaust port to allow the header to rotate if necessary when mounting your new muffler. 9. Using contact cleaner, clean the section of the header where the midpipe connects and allow to dry. Apply a light bead of high temp silicone for an improved seal.

To be fair, I don't know the model year of your bike, but I suspect that it's the same for all PC4 mufflers for the 150R.
 

[Bkicker]

It’s a 2008 and we wrecked and now there is a gap between reducer and silencer

[NoFiddyPilot]

Sounds like you need to heat the area that is now gapped and work it back into as close to original shape as you can. Then fill in any reasonable voids w/ high temp silicone as FMF recommends.

[Mojavemotokid]

This happend to me I have a simlair setup q4 with the stock header. It was a a pain to remove because of that gap but I ended up just pulling the silencer off and reinstalling it fixed the issue for me. Also I didn't use any silcone and it seams to be sealing fine. 

[Not Wearing A Mask]

This happend to me I have a simlair setup q4 with the stock header. It was a a pain to remove because of that gap but I ended up just pulling the silencer off and reinstalling it fixed the issue for me. Also I didn't use any silcone and it seams to be sealing fine. 

2019 CRF150R here. I’m using a q4 to the stock header pipe. Had to use the reducer they included. No silicone. Doesn’t leak. Fit with no problems.