Home made baffles and end caps for my CL77 Exhaust

Snakeoil · Post by **Snakeoil** » Tue May 03, 2011 12:21 pm

I'm sure he means opening up the ports in the baffle to flow more exhaust. This will also make the exhaust louder.

Not sure how quiet these are, but a lot of folks use them in various straight pipe set ups on lots of different brand bikes.

My understand on how all this works is you have to slow down the gasses. That's were the small holes come into play in the baffle. You slow them down, which providing sufficient flow area to not create excessive back pressure. If you look at the baffle tubes in the stock muffler, the holes are much smaller, but there are a lot more of them and the tubes are much longer. So you provide more than sufficient flow area, but the gasses are slowed down and a pressure drop is taken at each little holes such that the noise is reduced. This is the same basis for silencers on firearms.

I included a cap on the end of my baffles to force the entire flow volume thru the holes drilled in the baffle. My goal was noise reduction and restoration of some bottom end. If the set-up had run too rich and was also extremely quiet, I was going either open up the holes or drill the end cap. Last resort would have been removal of the end cap. I also made the aluminum tips a smaller diameter to emulate the outlet on the OEM muffler.

I've never done anything like this before. I just used what info I had picked up over the years working with inlets and exhausts on gas turbines, info I'd recently picked up regarding silencer design theory and worked within the dimensional limits of the final straight sections of the exhaust pipes. I got lucky and it worked so that's why I shared it here, so others could save the noodling time and just duplicate my baffles. If I was retired, I'd probably offer to make them for others. But as long as I'm working full time, free time is for the wife, the dog and me.

Forget Snuff-r-nots. They barely make any difference between open and closed.

If I had not made my baffles, I was going to go with a pair of Bates shorties, which EMGO now replicates. A couple of my friends have them and although pretty loud, sound much better than straight pipes. My thought was a set of baffles like Hotshoe suggests in the pipes and then the shorties after that. I think that would give you a nice deep exhaust note that would all make the bike socially sensitive.

regards,
Rob

Hotshoe · Post by **Hotshoe** » Tue May 03, 2011 7:05 pm

geosar wrote:Thank you Hotshoe,

What do you mean by "open them up"?

George

The Whitney baffles are way shorter than stock George so I didn't cut off any length but the restrictions are created by can-opener looking holes punched in the body of the baffle that looked too restrictive to me.
After I got them to fit in the pipes, I pushed the can-opener tabs back about halfway to the side wall to open up the baffles so they aren't so restrictive but still reduce the dBA to an acceptable level.
I've never liked Snuff-or-Nots because they seem to rob alot of torque and those little pins inset into the knob fail regularly.

geosar · Post by **geosar** » Tue May 03, 2011 10:15 pm

Thank you for the ideas. I ordered the Whitney baffles. They look like EMGO baffles. The I.D. of the pipes is 1 3/8 inches.

So now to compress the tubes 1/4 of an inch.

George

Scram64 · Post by **Scram64** » Sat May 07, 2011 12:14 pm

FYI
Here is one example of the Honda baffles.
Seems like they had two styles. One had a end cap and one had a open end with a pin.

geosar · Post by **geosar** » Sat May 07, 2011 1:29 pm

Here are some pictures of another original style baffle. 1 3/8 inch OD. Sure would be nice to find some like this.

George
Arizona

Snakeoil · Post by **Snakeoil** » Sat May 07, 2011 5:41 pm

Thanks for posting those, George. They are actually pretty easy to make if you had the inkling. You could probably use washers of the correct OD and ID (gotta get lucky though on sizing) for the support collars and then just a hack saw and a hammer and punch for the offset baffles. Last bit it a drilling exersize. You could simple crush the end of the tubing and get the same effect as that closed end. I think the pin across the back end is simply to facilitate a handle for removal.

I'm happy with my baffles. But I am curious about how well these OEM baffles work at bringing down the dB. George, if you get some free time, could you please put some dimensions to those baffles? Tubing ID and OD, lengths of the various sections, etc. If you are willing to do this, I'd be glad to make a digital sketch and send it to you and you could just fill in the dimensions on the sketch. We could post it here in case others would like to try and make their own.

I have to admit that intially I preferred the original muffler because it just looked right to me. But now that I have straight pipes, I've changed my mind and really prefer that look.

regards,
Rob

geosar · Post by **geosar** » Sat May 07, 2011 8:26 pm

Here is a rough drawing with some numbers. You are correct, the wire is for twisting it out of the pipe. There is also a threaded hole in the rear flange to accommodate a small, chrome bolt. That is a 7 inch ruler at the bottom.

George