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07-17-2022, 07:19 PM | #1 |
Join Date: Feb 2021
Posts: 994
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Aluminum vs stainless steel exhaust? Or something else?
I am warming up to my newly aquired TRB7D, and I am considering an aftermarket exhaust. I have been looking at eBay, and they have some stainless, and some aluminum ones. The cheapest ones range from $70.00 to $77.00. I don't want to run into issues like having to bend the clutch arm. I can weld decently, and so I wonder if I would be better off to just get rid of the catalytic converter, and buy an aftermarket muffler? When I had my Brozz 250, I gutted out the cat,and opened the back of the muffler, but I would rather not fool with the stock muffler on this bike. It's not whisper quiet now with it's stock exhaust, like the Brozz was with it's stock exhaust, so I assume it's not as restricted. I have seen claims of 2-5 HP increases . That seems like it's too good to be true on a 15hp bike. What do you think ? Should I just mod my pipe, and replace the muffler, or do full exhaust? Aluminum, or stainless?, Or just leave it be ? The only reason I am thinking about doing something is for a little more usable power. If you don't think I will gain over a half HP, then I probably will leave it be, but if I could add ,say one,and a half HP, then I would think that it would be worth it to gain 10% over current HP.
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07-17-2022, 08:22 PM | #2 |
Join Date: Feb 2021
Location: Kansas City
Posts: 2,625
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You can probably get a couple of horsepower, but also a more willing rev and power will develop earlier once the pipe is opened up and the carb is rejet. That is what I experienced on the storm, but I don't have dyno numbers!
The muffler section is a heavy steel part. If anyone has removed/replaced, can you weigh it? The head pipe, on the other hand, isn't a very heavy section. If you want better flow and less weight without buying a full exhaust, slice out the cat in the headpipe, weld it back up, and buy a lighter and higher flow tailpipe. This might mean cutting/fabricating a modified muffler mount. Or you can do what I did... just drill a few holes in the tailpipe to relieve the pressure. I guess we are not talking about a high performance conversion either way Aluminum versus steel might be more about cost or fit, but aluminum should be lighter (and dent more easily). But it is worth doing. The difference between 14 and 16hp is noticeable! |
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07-17-2022, 09:30 PM | #3 | |
Join Date: Feb 2021
Posts: 994
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07-17-2022, 09:46 PM | #4 | |
Join Date: Feb 2021
Location: Kansas City
Posts: 2,625
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07-17-2022, 09:56 PM | #5 |
Join Date: Apr 2017
Location: Omaha, NE
Posts: 8,100
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Most of the cheap exhaust systems for the crf are a low grade 400 series stainless steel pipe. The muffler body is the part that is aluminum. They are just calling it one or the other depending on how they choose to describe it.
Functionally they are all the same. Fitment wise. 3 of those exhausts installed on 3 different bikes 2 Hawks and one brozz, I have never had to bend the clutch arm. Ever. I have also never had to use a bracket to hang the muffler down. The only real tweaking I ever needed to do was ping in the pipe ever so slightly on one to clear the clevis on the clutch arm when it was retracted. Didn't hurt performance at all, and wasn't visible either. The real trick is to not tighten any bolts until the system is installed. This let's you adjust things to get clearances right. The only fitment issue that is fairly universal is airbox clearance on that back corner. It's so close the radiant heat melts it. We solved it on the Brozz with stick on heat reflective tape and a fiberglass heat sleeve around the pipe
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08-01-2022, 06:34 PM | #6 | |
Join Date: Feb 2021
Posts: 994
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Think it's mainly because the bracket on the muffler is mounted more towards the inlet. It looks ad though it would have probably reached the factory mounting hole if the bracket was on the outlet end of the muffler.. I am a little disappointed that I couldn't use the plastic piece that attached to the stock muffler, and I wish the muffler ran back a hair farther, if it did, I think the bracket on the muffler would fit the factory mounting hole . I may try to get a piece of stainless,and extend it. The power is better, and it runs high rpm more free. I rode it about 25 miles today, and my pipe is already a bronze color. |
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