total modifacation of the stock exhaust...!!!

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rogergendron1

rogergendron1

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here is what i have done to my stock black cat muff...

1 i cut the exhaust in two then cut off the cat converter, it was so clogged you could not even see though it when held up to the light

2 i then cut the headder tube that protrudes into the exhaust chamber bback to the verry begining

3 i cut out and removed the stinger pipe and drilled the hole out to fit a 3/4 inch universal glass pack.

4 i then got a exhaust pipe joint from auto zone that fit inside the exhaust chamber and welded it together effectivly extanding the exhaust 4 inches

5 threaded in the glass pack muff

6 paint as desired

the bike sounds a lot like a 4 stroke dirt bike with the muff on, with just a 1/2 id sstinger it sounds like a 50 cc 2 banger ... ring a ding ding ping ping ping.... so i leave the muff on cause i do not want to anoy my niegbors lol plus i notice no differance in power between the two so ...
the diff in power between stock and modded well... that is a huge diff ... i got verry noticable power everwhere and a lot on the top end !!! the styock cat was so restrictive you couldnt even see though it and it made the motor rev slow and make no top end ... now it rips !!!


the big hollow long tube after the header pipe acts sort of like a x chamber although its not as good as one properly angled and conned this stock exhaust now has a little band that comes on once you reach the upper rpms !


pics of mods ....
 

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rogergendron1

rogergendron1

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as you can see i cut the exhaust 1 in down from the first weld to expose the cat... then i cut the cat off at the wels to the headder tube and cut the header tube baack as far as i could....then cut off the cap for the cat so i could inspect it...
 

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rogergendron1

rogergendron1

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what i saw was a veeery restrictive cat that appeareed clogged ! and there was only 5 tiny holes for the motor to breath through ! not even holding to the light could i see though it !. after removing the cat i drilled the end cap out to fit a 3/4 glass pack and a 1/2 stinger pipe i made...
 

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rogergendron1

rogergendron1

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now that the exhaust is fully gutted and compleatly hollow nd the stinger installed it needs to be welded together... well i thought extending it would help low end power so i added a 4 inch section of 1 and 7/8 standard car exhaust tubing to the center ....
 

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rogergendron1

rogergendron1

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i put it on the bike and gave it a test run

wow !!!! the throttle responce is amazing now compared to stock !
it reves much quicker and revs higher !
power increased every where and i gaind plenty of speed !!
there even seems to be an expantion chamber effect at higher rpms !!!

the stinger was a little loud for my taste lol it sounder like a 50cc 2 stroke pit bike !!! so i screwed the 3/4 glass pack on and it quieted down a lot , now it sounds like a 50cc 4 stroke when idle and a nicely muffled 2 stroke when reving or under load !!!

pics of the finished pipe !!!
 

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rogergendron1

rogergendron1

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all in all if you have acsess to a welder i would highly suggest gutting the cat from your black cat exhaust !!! also extending it 4 inches seemed to add some torque !!! it is so resrtictive you can hardly see through it even in direct light ! i am shure it cloggs easy too so, also the cap for the cat only has 5 small 1/4 in outlet holes for the motor to breath !!! imagine trying to breath though a 6 inch long metal bee hive with 5 small holes in the end ! that is what this cat does to your motor !

my next mod is going to be to make a deflector cone that welds on to the end where the cap goes on and a defuser cone on the front where the header connects then do an upswept header, to make a long expation chamber out of the stock pipe !!!

i will post a video of the bike running and idleing so you guys can hear the way it sounds and rev's now, but will have to wait till tonight to get that done so hears for now !
 
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rogergendron1

rogergendron1

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on a side note ...

the black cat exhaust is verry heavy !!!! its heavy because of the cat !!!

the catalitic conveter is made from verry heavy guage steel and has a heavy 5/16th thick steel cap on it and massive welds ! the cat itself is not light ether ! the cat that was cut from my exhaust wieghed about 3lbs or more !!!!!!!!!! that meansby removing the cat i reduced the whieght of my exhaust by nearly 40% and reduced the stress on the jugs studs or bolts whatever you use !

also vibrations seem to be a lot less with a free flowing exhaust to the point of me noticing right off the bat .
 
mew905

mew905

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light weight tends to favor high frequency resonance, so it may have reduced vibrations in the low end but in the high they'll come back, though most likely not nearly as bad. I wanted to do this but I dont know anyone who welds nor have the equipment to do so. My cat is much, much longer, reaches all the way to the end (maybe thats just a tip or something?) and I gained a significant boost from drilling four 1/4" holes into it, but reinstalling the end cap reduces my power again, but also reduces the noise. I have an SBP pipe now and can't seem to get it working properly. It's tuned length is for ~8000 RPM, but it kicks in and dies out around 4800 RPM. I do have slightly more power but my powerband is much higher than 4800, so I dont feel much of a boost (though it is noticable). Jag and I are at a loss for why it's acting this way. Colder temps would make a tuned length longer (as the speed of sound slows at lower temps), and I dont think ignition timing has any effect at all on the pipe. I am using a flex pipe, but I think the issue is the pressure waves are being deflected by the flex pipe's innards, causing it to react as a longer pipe, and killing the power effects. I really need to get the proper tubing for it... haha.

But for the stock exhaust x-pipe effect, I imagine when you get on the pipe, it'd almost be like hitting a nitrous switch, just a sudden burst of power (steeper angles make sharper boosts).
 
rogergendron1

rogergendron1

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mew905 said:
light weight tends to favor high frequency resonance, so it may have reduced vibrations in the low end but in the high they'll come back, though most likely not nearly as bad. I wanted to do this but I dont know anyone who welds nor have the equipment to do so. My cat is much, much longer, reaches all the way to the end (maybe thats just a tip or something?) and I gained a significant boost from drilling four 1/4" holes into it, but reinstalling the end cap reduces my power again, but also reduces the noise. I have an SBP pipe now and can't seem to get it working properly. It's tuned length is for ~8000 RPM, but it kicks in and dies out around 4800 RPM. I do have slightly more power but my powerband is much higher than 4800, so I dont feel much of a boost (though it is noticable). Jag and I are at a loss for why it's acting this way. Colder temps would make a tuned length longer (as the speed of sound slows at lower temps), and I dont think ignition timing has any effect at all on the pipe. I am using a flex pipe, but I think the issue is the pressure waves are being deflected by the flex pipe's innards, causing it to react as a longer pipe, and killing the power effects. I really need to get the proper tubing for it... haha.

But for the stock exhaust x-pipe effect, I imagine when you get on the pipe, it'd almost be like hitting a nitrous switch, just a sudden burst of power (steeper angles make sharper boosts).
Click to expand...

yeh it does have a x chamber effect !!! i have been riding it a week now ! the x chamber effect kiks in up high though but thats ok cause its not too high i can still play with the throttle.

i think extending it 4 inches helped with broadening the range

the header length is the same as stock and woul benifit from having 6 in added to it

all together it a lot more free flowing ... i can blow through it with no resistsnce where as the stock i could feel clogging

plus it sounds great and reves a lot quicker..


cut it up and bring it to the muffler shop !
 
rogergendron1

rogergendron1

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i will say this....
the 2 best mods you can do to stock parts is ...

1 decking the head waaay down

2 gutting and extending the exhaust adding a few in to the header

just those two mods alone make the grubee a whole new anamal !! the exhaust was so restrictive ..... i ... i ... i couldnt even see through the damn thing lol
 
A

abefroman

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Sep 13, 2013
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Ok, i wanna do this to my exhaust. i can cut, grind, and weld just fine. However, I've never seen the inside of the exhaust, so let me know if this is the correct procedure (and some questions)


1) unscrew the nut at the bottom of the exhaust and pull the cap and attached tube out.
2) cut the body of the exhaust 1" down from the top weld
3) I'm assuming from the pictures that when I pull the two halves apart where I cut the body that the cat is the part that is still attached to the top part, right?
4) cut the cat off from the top part
5) get a 4" exaust piece from auto zone - insert it where the cut was made and weld it all back up.

6 ??? what about the lower half of what I cut out ? I took the bottom cap off and theres a long tube attached to it. Am I supposed to cut that back as well?

I dont understand these two things......

i cut out and removed the stinger pipe and drilled the hole out to fit a 3/4 inch universal glass pack.

5 threaded in the glass pack muff[/I]


what exactly is the stinger pipe, universal glass pack, and threaded glass pack muff ? is this something you bought at auto zone ?
 
bluegoatwoods

bluegoatwoods

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Jul 29, 2012
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Well done and very ingenious, rogergendron.


I'm a bit surprised I haven't noticed this thread before. Improving the exhaust is something that I've thought about for a long time. But I haven't tried, except an attempt five years ago that almost worked.

The answers to abefroman's questions will help me understand the process better.
 
maniac57

maniac57

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Oct 8, 2011
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abefroman said:
Ok, i wanna do this to my exhaust. i can cut, grind, and weld just fine. However, I've never seen the inside of the exhaust, so let me know if this is the correct procedure (and some questions)


1) unscrew the nut at the bottom of the exhaust and pull the cap and attached tube out.
2) cut the body of the exhaust 1" down from the top weld
3) I'm assuming from the pictures that when I pull the two halves apart where I cut the body that the cat is the part that is still attached to the top part, right?
4) cut the cat off from the top part
5) get a 4" exaust piece from auto zone - insert it where the cut was made and weld it all back up.

6 ??? what about the lower half of what I cut out ? I took the bottom cap off and theres a long tube attached to it. Am I supposed to cut that back as well?

I dont understand these two things......

i cut out and removed the stinger pipe and drilled the hole out to fit a 3/4 inch universal glass pack.

5 threaded in the glass pack muff[/I]


what exactly is the stinger pipe, universal glass pack, and threaded glass pack muff ? is this something you bought at auto zone ?
Click to expand...
The stinger is the small outlet pipe in the cap. Cutting off the excess length will make it flow better and also make it a bit louder. I have had good results replacing the stock stinger with a short 1'' dia. outlet.
 
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