How do you drill out stock mufflers

[Navigator]

A friend may be selling me his Jards next summer but as an interim mod, I am considering drilling out my stock mufflers. I have to admit that at 18K miles, my stock mufflers (w/CAT bypass) are starting to get a mellower tone and if I drilling them out will help that along a bit I am willing to break out the old drill and have a go at it. However, I do not want to ruin them. Years ago I drilled out a set of aftermarket mufflers on my 1976 KZ900 and they sounded horrible, like a Jap bike trying to sound like a Harley.

A few questions on the procedure.

- How is this best done and what size bit should be used?

- How many holes should be drill and how long a bit must be used. That is, do you drill through several layers of baffles or just the end plate?

- For those who have done this, how did you like it? Was the sound better, deeper, throatier or did it give it a tinny sound?

Thanks up front.

 

[Bishop]

Mike,

Mine are drilled out and I'll never use them again, you want them?

Then you could have a back up if you end up not liking it.

 

[Geek_Law]

If you end up not using Marcus' pipes, I have a 4x foot long drill bit with a 1" head that you could use. Should make for a fun time.

 

[Navigator]

If you end up not using Marcus' pipes, I have a 4x foot long drill bit with a 1" head that you could use. Should make for a fun time.

Yeah that sounds like a real fun time....

 

[Geek_Law]

If you end up not using Marcus' pipes, I have a 4x foot long drill bit with a 1" head that you could use. Should make for a fun time.

Yeah that sounds like a real fun time....

It's long enough that I mistakingly drilled clear through a floor joist and up into the subfloor and through the carpet ... but I only did that twice.

Good times.

 

[Barbary Coast rider]

Somewhere in here there is a post from about 1yr ago..that the Jars have an irritating headache causing high pitch noise...might check it out Mike.....

 

[NativeOne]

I have the Jars on mine and they never cause a headache and I've never noticed any high pitched whine! Of course, no one rides on the back of my bike either, that may be the difference! :lol:

Native One

 

[krothnbrg]

Mike,

Mine are drilled out and I'll never use them again, you want them?

Then you could have a back up if you end up not liking it.

Markus, if you don't give these away I'd be interested in taking them off your hands. Is there any need to remap?

 

[hoganator]

I cut mine off 3 inches back pulled the 2 back baffels out put the tips back on sounds GREAT with cat bypass 8)

 

[Bishop]

Mike,

Mine are drilled out and I'll never use them again, you want them?

Then you could have a back up if you end up not liking it.

Markus, if you don't give these away I'd be interested in taking them off your hands. Is there any need to remap?

My professional advice would be that any time you change a vehicle from it's out of the box OEM design, you should remap it.

Unprofessionally, a 12-minute will probably be fine but you should think about a remap, if nothing more, at least the TORs tune.