I’ve been a silent naysayer about drilling out the exhaust. It’s just one of those things that’s a personal choice, and it was something I didn’t want to do as I normally don’t like altering the stock parts, but events of late have changed my mind. There have been a couple of events recently on the road where I thought louder pipes would have helped, plus with the way things are going right now, I just don’t think I’m going to have the funds to purchase the pipes I want for quite a while.
There are plenty of posts on various forums describing and showing the muffler being drilled, and from what I’ve seen there seems to be 3 popular methods to drilling, so I’m going where pretty much everyone else has gone before.
Will this mod void the warranty on your bike? No
Will it void the warranty on the muffler? Absolutely!
You've been warned.
So let’s get started!
What you’ll need:
12 inch extension
1 1/2 inch hole saw,
1 1/4 inch hole saw,
3/8 inch drill bit
Decide what hole(s) you want to drill. Many have opted for a single large hole using either the 1 1/2 or 1 1/4 inch hole saw, while others have drilled 6 holes using the 3/8 inch bit. The thinking being that the multiple holes diffuse the exhaust which creates a more mellow and less “blatty” sound. I have no point of reference among them, so I can’t help you decide which way to go. The 1 1/2 inch is the largest you can drill out and seems to be the most popular, so this is what I did.
We’re going to be attacking the muffler from the rear:
About 10 inches down the pipe is the baffle plug we are going to be drilling out. I’ve tapped it with the drill bit, so that’s the shiny spot in the middle:
Put together the drill, extension and bit:
Run the bit down the pipe:
Carefully start drilling:
NOTE: You know how to drill. Stop/start the drill a few times so the pilot bit can get a bite, then take ‘er easy.
Once you drilled through, start up the bike to blow out the plug.
WARNING! Don’t have anything or anyone directly behind the bike, as this piece is going to come flying out. It’s not a nuclear missile, but no sense being careless.
Yah, yah, I did start drilling with a bit and changed my mind.
Here’s the result of your labor. You can see it’s now a straight shot through the baffle:
And that’s all there is to it!
How does it sound? Not too bad! Seems to have a pretty throaty sound to me without being overly loud.
First ride impressions:
This mod really didn't add a lot to the volume, which is fine with me. There is a bit more of a rumble to it on acceleration and when you give it an extra twist, but pretty mellow otherwise. I like it!
Now, what really surprised me is how much the engine has smoothed out since doing this mod. Even with a fuel manager and ThunderAir kit I still had some low end chugging, but removing the baffle plug has almost completely eliminated that, she feels smoother over the whole power band and it seems she has more power overall. I can't believe how restricted the stock exhaust was. This improvement alone was worth the mod and now I wish I had done it a long time ago!
There are tons of examples and discussions about doing this mod , so definitely don’t just take my word for it. Do a little research before deciding what you want to do.
If you want a good description of what is going on inside your muffler, Kaelar has provided an excellent writeup:
Oh, and for pity’s sake, use a good drill bit! Mine was cheap and caused this to be a far larger effort than it should have been!
Potestatem obscuri lateris nescis