'75 exhaust "castle nut" removal

[scott s]

I have a nice set of stock exhausts for my '75 XS650B. There is an exhaust gasket (part #9) that appears to go between the "castle nut" and the mufflers. How do you get that nut off?
The mufflers are in nice shape. I'd like to change that gasket, but not at the expense of damaging the mufflers.

 

[Capt_Zoom]

I'm not sure either but the one on my '77 is immovable. I've tried different spanner wrenches, channel locks, pipe wrench...nothing works. I think I'm going to end up having to cut mine off.

 

[5twins]

You need a hook spanner, something like the wrenches used for setting steering head bearing tension or adjusting rear shock spring preload. But with that thing being together for 30+ years, I doubt it will loosen up easily. Heat and penetrating oil might help.

 

[scott s]

Well, if it's THAT tight, I probably won't have an exhaust leak because of that gasket, huh?

 

[scott s]

But this brings up another question....what seals the mufflers to the head pipes? They slip on easily, but what prevents exhaust leaks?

 

[xjwmx]

There's a local friendly muffler shop I've used to free up various screws and bolts for me. And they will charge me like five or six dollars. They will heat it up red hot and work it back and forth a little. They get lots of practice freeing things up like that in the normal course of their work and are real skillful at it.

 

[scott s]

I now see how the gasket fits in there and creates a seal to the headpipes. I have the crown nuts soaking with PB Blaster. I'll see if they'll come loose soon.

 

[scott s]

I got one of them off very easily after soaking with PB Blaster. I need another set of hands to work on the other one.

Once I get the new gasket on, do you tighten the castle nuts while the mufflers are off the bike?
Or do you slide the nuts on the header, slide the muffler with gasket installed onto the header and THEN install/tighten the castle nut?

 

[5twins]

Install everything loose on the headpipe, then tighten the castle nut. That nut pinches and puffs up the gasket, sealing it to the pipe, so don't tighten things down unless the muffler is on the headpipe. I would anti-seize the heck out of the castle nut so it will come off easily next time. It probably doesn't need to be super tight, just tight enough to compress and seal the gasket.

 

[5twins]

In your parts pic, you'll see a clamp (#11). This should have tabs on it to fit some of the notches on the castle nut and keep it from coming loose.

 

[scott s]

I have the clamps but mine don't have any tabs on them.

I got the other nut loose, too. Capt. Zoom, try taking a small pick tool and scraping away the gasket from inside the pipe. I started out just trying to scrape a groove in it so I could spray PB Blaster in there, but it started digging the gasket out. A squirt of PBB and I was able to place a long screwdriver across the nut and use it as a spanner to break it free.
Came loose rather easily once I scraped out the old gasket and sprayed it down.

Thanks for the help everyone!