Hawk exhaust mod/hack complete

LunaTech · 08-19-2016, 09:21 PM

Well I decided to gut the cat on my Hawk. Just cut out a "window" and it pretty much just popped out. Welded the "window" back in, checked for leaks and painted. I also got froggy and made a new insert for the muffler. Went up to 1 1/2 inch pipe. Made the insert using EMT conduit and a 4" square electrical box cover (being an electrician stay with what you know). Sounds deeper and a little louder but not much louder. Can definitely tell a difference in power as it gets to 55 faster/easier and cruise's at 50 effortlessly. I need to get a long drill bit and drill some holes in the baffle in the muffler to free up some more flow and then will probably re-jet again. Pretty good mod for under $20. Here are some pics.

CSR_Sprocket · 08-19-2016, 09:38 PM

Quote:

Originally Posted by LunaTech

Well I decided to gut the cat on my Hawk. Just cut out a "window" and it pretty much just popped out. Welded the "window" back in, checked for leaks and painted. I also got froggy and made a new insert for the muffler. Went up to 1 1/2 inch pipe. Made the insert using EMT conduit and a 4" square electrical box cover (being an electrician stay with what you know). Sounds deeper and a little louder but not much louder. Can definitely tell a difference in power as it gets to 55 faster/easier and cruise's at 50 effortlessly. I need to get a long drill bit and drill some holes in the baffle in the muffler to free up some more flow and then will probably re-jet again. Pretty good mod for under $20. Here are some pics.

Nice work!

If you get a chance, could you post photos of the insert that you made?

LunaTech · 08-19-2016, 09:52 PM

Quote:

Originally Posted by CSR_Sprocket

Nice work!

If you get a chance, could you post photos of the insert that you made?

I can but my welding sucked and the holes are no where close to lined up.

I'll try to get a pic of it tomorrow and post it though. Just don't laugh

pistolclass · 08-20-2016, 01:00 AM

I see everyone cutting windows in the cat and gutting it. Can't you just cut the cat out and weld up a piece of exhaust pipe? I know I'd end up with stitches trying to dig those things out.

LunaTech · 08-20-2016, 07:42 AM

Quote:

Originally Posted by pistolclass

I see everyone cutting windows in the cat and gutting it. Can't you just cut the cat out and weld up a piece of exhaust pipe? I know I'd end up with stitches trying to dig those things out.

You can but then you would have to get the alignment back for the pipes to line up and you would also have to weld the heat shield nut back on and get it's alignment back right. Just easier to cut the window and gut. Just be careful and and no stitches will be required. Use welding gloves if needed. It really did come out easy.

pistolclass · 08-20-2016, 08:00 AM

Quote:

Originally Posted by LunaTech

Just be careful and and no stitches will be required. Use welding gloves if needed. It really did come out easy.

yeah... careful..... When signing up for this forum I couldn't decide between the name pistolclass or butterfingers.

ckrug4 · 08-20-2016, 09:49 AM

I cut the pipe after first weld. Scratched some crows feet marks before I cut so I could line it back up. Used a tire tool to punch out baffles in muffler. It's a bit louder but worth the trouble. Combined with new jets and open up air box ALOT, I can hit 62 mph pretty easy. Accelerates up hill better. I can cruise 55-58 easy. Made it pull stronger for sure.

pcspecialist · 08-20-2016, 01:02 PM

Quote:

Originally Posted by LunaTech

you would also have to weld the heat shield nut back on

even though I gutted mine through a "window", I removed the heat shield nuts so that I could wrap it and hose clamped nuts over the wrap.

https://www.facebook.com/photo.php?f...6&l=5755794f96

pcspecialist · 08-20-2016, 01:10 PM

Quote:

Originally Posted by CSR_Sprocket

could you post photos of the insert that you made?

Here's the one I "made". Fits perfectly and polished up real nicely.

Here's where I "made" it.

https://www.amazon.com/dp/B001654JK0

I just wish it were exactly as pictured on Amazon because it would have made it real simple to clamp a screen to the part that would have extended into the muffler.

Here it is installed:

https://www.facebook.com/photo.php?f...3&l=cbb9f2f6d4

pcspecialist · 08-20-2016, 01:25 PM

Quote:

Originally Posted by LunaTech

I need to get a long drill bit and drill some holes in the baffle in the muffler to free up some more flow

Being an electrician, you should already have the drill bit needed, I already had mine for doing cable runs through walls.

Don't go overboard as I did, I think 3 holes would have been enough but I have even more than you can see here:

LunaTech · 08-20-2016, 02:08 PM

Quote:

Originally Posted by pcspecialist

Being an electrician, you should already have the drill bit needed, I already had mine for doing cable runs through walls.

The only long bit I have is a wood bit. The bit extension I have might hold a metal bit but I'm not sure. Forgot I had it. I'll have to check it out. Thanks for advice about drilling too many holes. I remember reading it on your post about modifying your exhaust.

LunaTech · 08-20-2016, 03:41 PM

OK, here is the insert I made. Welds look like crap. My auto darkening welding helmet didn't darken on the first arc and from then on all I could see was a red spot where I was welding. It sticks but it ain't pretty but NORMALLY no one will see it. I still need to de-bur the holes and add a spark arrestor screen for when I go on National Forest land.

BlackBike · 08-20-2016, 09:57 PM

Luna t... I often wondered if you could get away with a 3 way cut and bend the window open for access. Then just 3 cuts to weld closed . I won't know till I get in there and do it.

Luna t.. you are far too humble, the fact is job done ! Results are what counts

LunaTech · 08-20-2016, 10:54 PM

BlackBike... I'm not sure 3 cuts would work but it never hurts to try. The cat material is glued/stuck in several spots all the way around so bending might be difficult. I just used a dremel with a cut off wheel (actually used about 4 wheels) to make the long cuts and my hack saw to make the two end cuts (across the radius). The cat material came out stuck to the "window" I cut out and I just used a screw driver to pry it off there.

Weldangrind · 08-22-2016, 12:45 PM

LT, thanks for taking the time to share your exhaust surgery with us. Your method is exactly what I would do if I had a cat to excise. I might also try BB's suggestion of cutting three sides only, with a score to relieve the section to be bent.

I really like the exhaust tip concept. You might decide to try another version that borrows from 2LZ' design, which has a plug in the inlet end of the tip. That forces exhaust to enter the tip through the small holes on the sides, which can be tailored to suit your needs (and it'll pass a coat hanger test).

I've fabricated similar mufflers before, and my way is to use a little math. Calculate the area of the ID of the header and then calculate how many 1/4" holes would be required to equal the same area. Drill that number of holes and try it. I wouldn't drill holes any larger than 1/4", so that sparks can't easily find their way out.

08-20-2016, 09:57 PM	#13
BlackBike Join Date: Feb 2016 Location: George West, Texas Posts: 4,097	Luna t... I often wondered if you could get away with a 3 way cut and bend the window open for access. Then just 3 cuts to weld closed . I won't know till I get in there and do it. Luna t.. you are far too humble, the fact is job done ! Results are what counts __________________ ***************************************** 2015 Bashan"Blaze" BS250GY-31 (DB-07K-250) GONE 2017 Suzuki V Strom 650 XT "We are all born ignorant, but one must work hard to remain stupid." ~Benjamin Franklin~
	1

08-22-2016, 12:45 PM	#15
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	LT, thanks for taking the time to share your exhaust surgery with us. Your method is exactly what I would do if I had a cat to excise. I might also try BB's suggestion of cutting three sides only, with a score to relieve the section to be bent. I really like the exhaust tip concept. You might decide to try another version that borrows from 2LZ' design, which has a plug in the inlet end of the tip. That forces exhaust to enter the tip through the small holes on the sides, which can be tailored to suit your needs (and it'll pass a coat hanger test). I've fabricated similar mufflers before, and my way is to use a little math. Calculate the area of the ID of the header and then calculate how many 1/4" holes would be required to equal the same area. Drill that number of holes and try it. I wouldn't drill holes any larger than 1/4", so that sparks can't easily find their way out. __________________ Weldangrind "I figure I'm well-prepared for coping with a bike that comes from the factory with unresolved issues and that rewards the self-reliant owner." - Buccaneer
	1

08-20-2016, 01:00 AM	#4
pistolclass Join Date: Oct 2015 Location: connecticut Posts: 978	I see everyone cutting windows in the cat and gutting it. Can't you just cut the cat out and weld up a piece of exhaust pipe? I know I'd end up with stitches trying to dig those things out.
	0

08-20-2016, 09:49 AM	#7
ckrug4 Join Date: May 2016 Posts: 21	I cut the pipe after first weld. Scratched some crows feet marks before I cut so I could line it back up. Used a tire tool to punch out baffles in muffler. It's a bit louder but worth the trouble. Combined with new jets and open up air box ALOT, I can hit 62 mph pretty easy. Accelerates up hill better. I can cruise 55-58 easy. Made it pull stronger for sure.
	1

08-20-2016, 10:54 PM	#14
LunaTech Join Date: Jul 2016 Location: Jonesville, NC Posts: 136	BlackBike... I'm not sure 3 cuts would work but it never hurts to try. The cat material is glued/stuck in several spots all the way around so bending might be difficult. I just used a dremel with a cut off wheel (actually used about 4 wheels) to make the long cuts and my hack saw to make the two end cuts (across the radius). The cat material came out stuck to the "window" I cut out and I just used a screw driver to pry it off there.
	0