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General Category >> Rubber Side Down! >> Holes Drilled in Muffler
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Message started by ThumperPaul on 09/09/24 at 07:54:22

Title: Holes Drilled in Muffler
Post by ThumperPaul on 09/09/24 at 07:54:22

No wonder my muffler sounds louder than stock. It’s got at least 1 hole drilled in it. I think I feel another one, but I gotta take it off and look.

Thoughts? I’ve got the carb jetted for it without knowing the hole(s) were there.

Title: Re: Holes Drilled in Muffler
Post by oldNslow on 09/09/24 at 12:57:07

That wasn't drilled. My muffler developed a hole one day in that same spot. I think it's a rusted out spot weld from when the muffler was manufactured.

I don't have a welder now that I'm retired, and the hole in my muffler was about the right size for a 1/2" fine thread tap. There's a lot of metal there so I ran a tap into the hole, cut a bolt so it had about a half inch of threads on it, put red loctite on the threads and screwed it in the hole. It'e been in there for three or four years now.

My muffler does have a couple of extra holes drilled in it, but they are in the end on either side of the actual outlet. Provided by one of my bike's previous owners ;). My bike has the stock jetting and it runs fine despite the holes. I don't know how much louder than stock it is with the extra holes, but it's still pretty quiet. The mechanical noise from the engine is at least as loud as the exhaust.

Title: Re: Holes Drilled in Muffler
Post by DragBikeMike on 09/09/24 at 13:23:19

It's been gettin mighty hot around that hole. You can see the pretty rainbow circling the hole. IMO, any impact to jetting will depend on how far back the hole is. As long as it is at least 10.75" aft of the front edge of the muffler, it will be located in the last chamber in the flow path, so it won't have much impact on flow. If it is less than 10", then it will be in the first chamber and have a significant effect on flow. But either way, I don't think it will screw up your jetting since you dialed it in with that muffler installed.

I like oldNslow's approach, tap it and plug with a bolt. Since the wall is thin, fine thread is mandatory (UNF).

This old post shows you what's inside the beast and provides a full set of dimensions so you can figure out where everything is located.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1526453881

Title: Re: Holes Drilled in Muffler
Post by ThumperPaul on 09/09/24 at 14:49:56

Thanks guys. I do believe you are right, oldNslow. As I look at it more, it appears it’s been gunshot from the inside. The metal appears blown out and not drilled clean from the outside. Eyeballing it, it looks like it’s within 10” of where the muffler actually begins (excluding the clamping area).

There seems to be another hole forming in about the same area where the muffler faces the wheel/tire.

It does seem to be running hot (the pretty rainbow). Maybe I have my jetting too lean. Time to move the e-clip back down a groove on the needle. I feel like a drunker sailor dialing in the PWK38.

And maybe it’s time to install the dyna I have stashed on a shelf. Then plug the stock muffler with a cork. :o ;)

Title: Re: Holes Drilled in Muffler
Post by ThumperPaul on 09/11/24 at 13:15:31

I removed the muffler to get a better look. It appears someone plugged the hole. You can tell hot gases had been escaping out of it at one point. I can see an Allen head (bolt, plug, cap?) and there is some rough welding around the perimeter. There are 2 other spots about the same size but I can’t tell what was done there (like did the chrome fall off?).

DBM - I read through your thread. Good stuff. I didn’t see anything to suggest that there might be some type of fasteners in a row in this area. It like a row of 3 and 1 has the plug with the weld. The other 2 look rough. Like maybe somebody sanded down some welding, but there’s no evidence that hot exhaust gases leaked out in the other 2 spots.