ESR exhaust flange O-ring size

[Jerry Hall]

I gave up on experimenting/searching for the magical sealing compound for sealing pipes many years ago.  I do not know of any non metal compound other than asbestos that will take the average temperature of the exhaust flange and pipe flange for very long.  If there is something out there.............it probably is not affordable. 

Most new owners of the ATC250r and TRX250R never experienced how well OEM pipes sealed because they immediately removed the OEM pipes and installed an aftermarket pipe.   The majority of the aftermarket  pipe flanges were made of seamed tubing that was rarely round, the tubing was usually a sloppy fit on the exhaust flange and the welded seam of the tubing prevented any hope of any type of a controlled leak.

I think the Honda engineers had the solution on their original OEM exhaust flanges and pipe flanges.  These flanges had a metal piston type ring with the asbestos type packing on the end of the exhaust flange.  If the aftermarket pipe builders would copy the pipe flange that Honda had, use the long lasting OEM steel exhaust flange with the metal sealing ring and use the packing on the end of the flange it would eliminate the majority of the mess at the exhaust flange.

[broken1]

I use the OEM flange with the steel split ring & the OEM graphite seal with a bead of ultra copper around the graphite seal & rarely have any leaks. The trick is to dry fit the pipe first & make alignment marks before putting the rtv on & don't touch it for 24hrs once together.

[wilkin250r]

The more I experiment, the more I'm leaning towards the OEM solution.  The only pipe/flange combo I ever had that didn't leak was an OEM flange with the split ring and the OEM seal.

I'll try a few things, and I'll even give one attempt at a high dollar o-rings like Kalrez (at $50 each, but they claim 50% higher temp rating than silicone).  However, with all the other projects I have going at the moment, I can't promise when I'll get to it.