Exhaust leaks and baffling question

[teflon97239]

Rode everything since 1967, always wanted a TX/XS 650. Proud recent owner of a 74 and a 75.

Neither bike has had any major work, and both have obvious exhaust leaks at the clamps where the mufflers join the pipes. I might just reef the clamps down harder but those little bolts look fragile. Is there some perishable gasket material that burned away over 36 years? Both bikes will surely sound better when all the noise comes from the exhaust tips as it should.

So what do I put in there to get a good seal?

Also, the 74 is obnoxiously loud, which I assume means the baffles are shot or missing. That's fine, it's a rude looking bike and I like the racket. Used my throttle instead of that pipsqueak horn in traffic last week and got instant headwhip from the dimwit trying to cut me off like I wasn't there.

Sadly, the 75 sounds a bit (ahem) subdued by comparison. I would replace the mufflers with something exuding more testosterone, but they are those classic stock units pictured on the bike above in this website, and I want to preserve the look. Can I remove or replace something inside them to hear more grunt when I twist the gas? Then if I do, will I need to tweak the carbs somehow to compensate?

By the way, cool forum here. Just signed up. Thanks in advance for all ideas. [e-mail]

[650leo]

The bolts that hold the clamps tp the frame are not what seals the muffler to the headpipe. If you take that bolt out and slide the clamp aside you will see a nut. It has notches in the forward end. There is a wrench that turns this nut. There is a gasket that goes under the nut, as the nut tightens the gasket is squeezed between the muffler, nut and headpipe.
If you look under exhaust at Mike's XS you will see the gasket #07-4622, the nut #07-4621 and the wrench #35-5029
You can take the mufflers off by pulling the bolts on the clamps and at the rear foot pegs, then with a bit of wiggling they slide off the headpipes. At the parts store they sell several exhaust sealers. Apply a good coat on the headpipes and slip the mufflers back on. This may seal the leak.
The nut has been on there for 35 years, it may not come off.

[richard]

I have reveres cones on mine and they leak a little at that same connection. Mine has two crush sleeves one over the other that are supposed to seal when they are clamped, but they never seem to be 100 percent sealed so after every ride I have to wipe a little soot off the head pipe in front of the clamps. It kind of bugs me but I haven’t figured out what to do about it yet.

[650leo]

Have you tried an exhaust sealer on the head pipe and the sleeves before assembly?

[richard]

No I haven't, but I saw your reply and started thinking about it. That seems like it should work. Is there any stuff you can recomend?

[650leo]

Not really, a friend used some orange high temp silicone on his Shovelhead. I tried some gray stuff that looked a bit like plaster, dried hard. I think they have a copper colored stuff that may work.
I haven't looked to much lately. Check out the stuff at the parts store

[pamcopete]

Permatex makes a muffler sealer and various other exhaust sealing products:

www.permatex.com/products/Automotive/specialized_maintenance_repair/exhaust_system_maintenance_repair.htm

Check to see if your headers are double walled, as are most stock headers:



If the stock headers are double walled. The functional pipe is inside the outer pipe, so if you are going to use the stock headers with an after market muffler, you need an adapter that will connect the muffler to the smaller inner pipe. And, yes...the outer pipe does have drain holes in them, so if you just clamp the muffler to the outer pipe, the exhaust will leak out of the drain holes.

The outer pipe may also leak at the head flange as well. The outer pipes were not designed to flow any exhaust, so there is no guarantee that they are gas tight from end to end.


I used this adapter on my '81/H:



This is a 1 1/2 X 1 3/8" adapter available at most auto supply stores, #548520. The small end will fit tightly around the outside of the inner pipe. Clamp the muffler around the large end. There is no way to clamp the small end around the inner pipe, but it fits real tight, so you can either wait for the carbon buildup to seal it or apply some Permatex muffler sealer.




The small end is completely hidden inside the header, the big end is completely hidden inside the muffler.

This is what it looks like when installed.

[650leo]

Pete, on the older exhaust like on the 74 and 75 he has, the muffler was not welded to the headpipe. It was a slip fit and the gasket and a nut sealed the mufflers to the out side of the headpipe. The outer pipes tapered in and are welded to the inner pipe where the muffler is slipped on. This seals the two pipes together.
I'm not sure but I think they started welding the mufflers on the headpipes in 78 when the specials came out. I will check on the Yamaha-USA site, they have the parts fiches for the bikes.

[650leo]

From looking at the fiches, it looks like the standards till 79 had a two part exhaust. All the Specials had the one piece exhaust.
Teflon, I modified my stock mufflers with a 3/4 " pipe. With the mufflers off I knocked the baffle plate out of the mufflers. This makes it about the same as a straight through glass pac. A bit better breathing and a bit louder. I can here the pipes at most speeds but not obnoxious. A nice burble at idle.
It's cheap and works ok.

[richard]

Mine has a reducer sleeve set like mike’s P/N 07-0005 and it leaks at the splits in the reducer right at the clamp like in the last two photos Pete posted. I think I just need to fill in those splits with something that won’t damage my head pipes. The head pipes that came off my bike were double wall but somebody welded the mufflers on. They were a mess so I had to replace them with a new head pipe that is about eighth of an inch thick, which cost a little more. I think I’ll try some of that permatex to see if it works.

Pete that's good idea That might have save my old pipes if the hadn't welded on them first.

[5twins]

I've always had problems trying to get those reducer sleeves to seal. I try not to buy mufflers with them anymore, instead getting ones that fit the pipes correctly with no reducer. Richard, Mike sells those mufflers you have in the proper 1.5" size but for your bike, I would get his original repros.

[richard]

Well I planned on getting the stock replacement mufflers when I could scrounge up the money, but saw the reveres cones on eBay and figured they would get me by for the time being. The head pipes are Mike’s OEM type replacement, they seem pretty close to what I took off, thick like the OEM but only one piece. I’ve seen head pipes that were pretty thin. I’m I plan to keep working my way toward stock so reproduction would be my next step when I can afford it. I have over 8k in my bike now.

[teflon97239]

Good feedback all around on managing that exhaust leak. Thanks.

For now, I've popped the rotten old fasteners and mangled clamps off the 75. Bent everything straight (actually round) again, and replaced the wimpy hardware with heavier 8m bolts, nuts, and lock washers. At least the rattles and metal-on-metal sqeaks are gone. Now I know I don't need the same crown-shaped nuts I see on my 74, and I no longer dread wrecking any loose threads. The 75 doesn't have them. You never know what the last few owners did to a bike until you dig in and see for yourself.

650leo, I'm dying to know more about how you knocked out those baffle plates. This bike is so well muffled, it sounds like an old CB350... yaaawwwnn. I want just a bit more of that grumpy 650 sound without completely uncorking everything. Please shoot me more details so I can better picture what you described.

Thanks in advance - [e-mail].

[650leo]

The inner pipe in the muffler is perforated the whole length. About 1/2 way down there is a piece a metal kinda like an car engine freeze plug welded in this perforated tube.
I stood the mufflers up and dropped the pipe down into the muffler and a wack or two with a hammer knocked the plug out. I guess you could try it on the bike by just driving the pipe into the muffler.
When the plug comes loose it probably tore the perforated pipe some, hard to see into the muffler to tell. A better way might be to use a drill bit with a long extension and drill holes in that plug. If you start with a 1/2 inch hole, if that sounds ok stay there, if you want a bit more noise try a bigger hole.

[teflon97239]

Hey Leo, perhaps my quest for just a little more authorative exhaust sound will be even easier than what we imagined?

I was picturing what you described inside your baffles (or at least I thought I was) until I took a peek and found this Buck Rogers ray gun looking business in my tailpipes. I assume mine are stock 75's, but who knows now? As similar as these bikes are (TX A/XS B, C, etc.), I believe we're also seeing how Japanese engineering and manufacturing never clung too long to anything that could be made slicker or more economically. Bless Deming's heart.

So what do I do here to let out just a little more sound and incidentally allow improved exhaust flow? Maybe start with 1-3 little holes on each side? Perhaps end up with all 6 drilled out completely? Or is that just the wrong part to ventilate? Almost seems too simple, and with my luck it probably is.

Hopefully someone out there has been down this exact road with this exact muffler?

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