Does anybody have an idea of how hot the header-to-silencer junction gets on a tpical 4-stroke. In this case I'm thinking of a Raptor?

I recently installed an FMF slip-on spark arrestor and I am getting a slight leak where it meets the stock head-pipe. When the system heats up, it seals but makes a mess until it gets hot. There is no clamp or anything that makes a positive seal (like stock). I was thinking of a dab of high temp silicone or something - any ideas ?? FMF says "that's normal" !?!

 

That is one of the problems with the FMF tip. I suggest the Yamaha GYTR or HMF tip. The Yamaha tip has a great seal and clamp. (On occasion, I have found it necessary to cut the compression slots slightly wider for a proper seal)

 

I also have an FMF pipe on my Raptor...I love it, dont have any leaking or mess that u talk of...but my header gets real hat every time i ride in jeans i come home with a hole in my pants....plus if u ride a night the header will turn red sometimes.....

 

Check your stock silencer there was a woven copper gasket in there. It is tought to get out but it can be done or you can order a new one from Yamaha. Had the same problem originally

 

I noticed the gasket, but there is no positive pressure pushing the pipe against it?? It didnt seem like it would do anything without a clamp. Also, FMF said that it was not needed and it's not even mentioned in the instructions. I'll pull it apart and give it a try !

Any other ideas out there ??

 

White Bros. didnt say anything either but I noticed the leak right off. So I started to poke around and ask a few questions here. Someone told me about the gasket. My pipe was just that much larger in diameter that the fit is perfect with the gasket. No more leak.