Shortened muffler for 650R

Oops, first posted this on the general page, oh well.

Got home from work early today, so I finally got around to sectioning the muffler. Cut the endcap off right after the weld and removed a big section. In order to clear the HRC tip internals, I had to burn out a bit of the inner pipe which is a bit ugly, but hidden inside the muffler. I think she looks much better this way. A little louder, but not insanely so. I haven't ridden her yet due to my bitchy neighbors, but I am hoping to lose a bit of the excessive bottom end grunt and put it up top. Just wanted to pass this along because it is an easy, free project. Cnv0016.jpg

Cnv0015.jpg

looks kinda strange like that but it will prolly make her run like a champ!

thank god my neighbors aint like that....i could have the yoshimura wide open in my driveway all day and they would care.

Yeah, I may have gotten her a bit short. But this was more of a screwing around/ learning exercise since these cans are on ebay constanly for next to zero $$. And I guess the factory muffler performs OK, so might as well play around with configurations to see what works best.

I like it.

I guess I don't understand the theory behind what you did. The exhaust still exits through the same outlet.....but the volume of the can is reduced. Please enlighten me as to why you would expect a difference.

Other than that it looks pretty good, nice welding job.

Oops, first posted this on the general page, oh well.

Got home from work early today, so I finally got around to sectioning the muffler. Cut the endcap off right after the weld and removed a big section. In order to clear the HRC tip internals, I had to burn out a bit of the inner pipe which is a bit ugly, but hidden inside the muffler. I think she looks much better this way. A little louder, but not insanely so. I haven't ridden her yet due to my bitchy neighbors, but I am hoping to lose a bit of the excessive bottom end grunt and put it up top. Just wanted to pass this along because it is an easy, free project.

In order to do that, you should have lengthened the exhaust. Shortening the can will give you more bottom end...in fact, it was one of the cheap fixes recommended to do on the '02 CRF450 since it lacked a bit of bottom end :banghead:

Tiny positive note:

This may save the can from crumpling in the event of looping/ flipping your bike.

Not that we would do such a thing.

A little louder, but not insanely so. I haven't ridden her yet due to my bitchy neighbors,

now we know why you have bitchy neighbors...

I like it! HRC tip?

In order to do that, you should have lengthened the exhaust. Shortening the can will give you more bottom end...in fact, it was one of the cheap fixes recommended to do on the '02 CRF450 since it lacked a bit of bottom end :banghead:

no, i believe that you have it backwards. shortening the exhaust gives less bottom end and more top end. shortening the can decreases backpressure, increasing flow, which helps on the top end. i cut 3" out of my exhaust on my 426 and it is the same way. slight loss(if any) off the bottom but more top end in exchange. also, more noise because of less packing.

now we know why you have bitchy neighbors...

Haha; yep, they don't seem to care much for the CPI inframe drag pipes my banshee has, either. But I respect their right to quiet, so the toys only run if I get home from work early and no one else is home yet. Seriously, I had always heard that a shorter can reduced backpressure, equalling better top end/worse bottom. I was wrong? -Seems possible but not able to verify yet due to neighbor relations. The section I removed was also the area of the pipe with the baffles, so this may skew the results a bit in my favor. I also had the idea that it would no longer be able to be used as such a long lever on the fragile subframe in the event of a crash. The noise level with the HRC tip is louder but bearable, but with the open tip it may shatter windows- don't think that's gonna win me any prizes on my block!

shorter exhaust is more botom, less top.

The reason it reduces back pressure on other bikes is because you are taking away the amount of area that most mufflers (not our stock one) have to disrupt the air flow and sound. The core is a pipe with a lot of holes in it rapped with fiberglass. The exhaust hits these holes and spins into the fiberglass as does the sound. Our stock pipe has two baffles in the can that the muffler tip slips into, making the flow bounce against it's self. You removed these baffles making a straight shot to the muffler tip. You can do the same thing by knocking out the baffles but, it wouldn't be as cool as your short setup.

Now that you have the end cut off can you show a picture of the two baffle walls inside?

Now that you have the end cut off can you show a picture of the two baffle walls inside?

Sure, here ya go:

the first is the tip sideCnv0018.jpg

the second is the engine side Cnv0017.jpg

I think that gets the point across a lot better!

Yup. I forgot that we were talking apples- to -oranges in regard to glasspack style 2-stroke pipes versus plate baffled pipes. I am sure the gains were from lessening the surface area of the glass baffled core. My gains will simply be from removing the baffles, so I should definitely see some top end improvement, bottom end loss from this.

Nobody mentioned the WEIGHT LOSS!!!!! At least worth an equivalent .03 HP (but not to match the .034 HP gain from the louder exaust).

....sorry i couldn't resist

Nobody mentioned the WEIGHT LOSS!!!!! At least worth an equivalent .03 HP (but not to match the .034 HP gain from the louder exaust).

....sorry i couldn't resist

Don't bring up the sound level! Vector6 will start beating his dead horse again :banghead: Nothing about loud! :banghead:

Wait, out of control. 'll stop

Aside from a minimal weight loss and possible power gain, I don't see the added benefits. However it does look better. I had mine ceramic coated and stuck an FMF sticker on it. You wouldn't know the difference.

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