Exhaust mod questions

ChipToothy · 08-01-2018, 12:28 PM

Can we just cut the cat section from the header pipe and then refill the gap in line with a section of flex or aftermarket section pipe and clamps? Also as far as I know we can mod the Storm exhaust w/o having to mess with the carb? I tested a no air box ride and over 30mph the engine runs choppy. Clearing the exhaust is fine though from I can find. Not much info out there. Thanks.

ben2go · 08-01-2018, 04:34 PM

When opening the air intake or exhaust, the engine will run lean. That can cause burnt valves and other issues. Removing the cat may not be a big deal though. You can cut it out and section in a length of pipe but it needs to be sealed well to prevent running issues. and hot exhaust from burning your leg and pants. Most people either gut the cat or replace the exhaust. There used to be header pipes for sale that would probably be cheaper than a bodge job of pipe and clamps.

ChipToothy · 08-01-2018, 05:04 PM

Oh yeah, I’m trying to learn all I can before actually putting hands to it.

I don’t see how adding a replacement section is a bodge though. The muffler and header pipe are fitted together with way worse clamps and pipe than the auto store sells. You can get tough as nails everything for cheaper than the eBay kit except no Bashan fitted header pipes to be seen.

I just need to find the someone with an exhaust modded on the same bike to hopefully chime in.

Cravin01 · 08-01-2018, 05:44 PM

Not a giant increase with a very small amount of popping when letting off the throttle (lean). could be adjusted out with the fuel mixture screw. $20 to have it wielded at a muffler shop but I still went with the aftermarket exhaust, a much larger improvement with jetting required.

ChrisWNY · 08-01-2018, 06:02 PM

If you simply remove the cat and replace a section of the stock exhaust pipe, you'll definitely open up airflow through the engine but may not have to move up in main jet size. At the very least I'd shim the needle to richen your fuel mixture. If you go with the aftermarket performance exhaust, there's much more air going through the engine so a larger main jet (and richening the needle) becomes necessary or you'll run that engine too lean.

goat67 · 08-01-2018, 06:28 PM

Quote:

Originally Posted by ChipToothy

Oh yeah, I’m trying to learn all I can before actually putting hands to it.

I don’t see how adding a replacement section is a bodge though. The muffler and header pipe are fitted together with way worse clamps and pipe than the auto store sells. You can get tough as nails everything for cheaper than the eBay kit except no Bashan fitted header pipes to be seen.

I just need to find the someone with an exhaust modded on the same bike to hopefully chime in.

I used the ebay exhaust that everyone else has used, it works just fine for my Brozz.

What do you mean no fitted header pipe? You do need to enlarge or notch out the flange that bolts to the head but nothing dremel with a cut off blade can not handle or drill it out.

ChipToothy · 08-01-2018, 06:40 PM

Quote:

Originally Posted by goat67

I used the ebay exhaust that everyone else has used, it works just fine for my Brozz.

What do you mean no fitted header pipe? You do need to enlarge or notch out the flange that bolts to the head but nothing dremel with a cut off blade can not handle or drill it out.

I mean I can buy every piece at the parts store on my street but they don't carry anything that will even come close to a header pipe section fitting a motorcycle.

If it can't be done w/o carb work then I just won't mess with it. Project Next said in the video his felt better, ran great without the cat and he didn't have to touch the carb.

pete · 08-02-2018, 03:27 AM

Why didn't you turn the cat case into a power bomb
since you had it opened up...

Is a peice of tube the same dia as the header pipe
1/3 the length of the cat case welded on the engine end of the case..

It traps some of the returning pressure wave and drops the pressure in the header
pipe so the next exhaust charge dosn't have to fight so hard to get into the exhaust pipe...

..

Digger · 08-02-2018, 06:45 AM

I read somewhere about cutting the cat case in half and digging out the material from each of the case. I plan on using a pipe cutter for a clean cut. This process only requires one weld.

08-01-2018, 12:28 PM	#1
ChipToothy Join Date: Apr 2018 Posts: 819	Exhaust mod questions Can we just cut the cat section from the header pipe and then refill the gap in line with a section of flex or aftermarket section pipe and clamps? Also as far as I know we can mod the Storm exhaust w/o having to mess with the carb? I tested a no air box ride and over 30mph the engine runs choppy. Clearing the exhaust is fine though from I can find. Not much info out there. Thanks.
	0

08-01-2018, 05:44 PM	#4
Cravin01 Join Date: Jan 2018 Location: Forney Texas Posts: 498	Not a giant increase with a very small amount of popping when letting off the throttle (lean). could be adjusted out with the fuel mixture screw. $20 to have it wielded at a muffler shop but I still went with the aftermarket exhaust, a much larger improvement with jetting required. __________________ Visit me on YouTube at "Project Next"! https://www.youtube.com/channel/UC6KTCi2GVbfRDv-2XCqHhsg?view_as=subscriber 2017 Bashan Storm Keihen PZ30 Pumper Carb,115 main jet,35 pilot jet, gutted factory exhaust, Sambo Digital Speedometer,LED blinkers, H4 headlight,D.I.D X-ring chain 428,17/42 sprockets,UNI cone filter.
	1

08-01-2018, 06:02 PM	#5
ChrisWNY Join Date: Jul 2018 Posts: 212	If you simply remove the cat and replace a section of the stock exhaust pipe, you'll definitely open up airflow through the engine but may not have to move up in main jet size. At the very least I'd shim the needle to richen your fuel mixture. If you go with the aftermarket performance exhaust, there's much more air going through the engine so a larger main jet (and richening the needle) becomes necessary or you'll run that engine too lean. __________________ 2018 RPS Hawk 250cc Mods so far: 1. Mikuni VM26 Carburetor w/#115 main jet 2. 17T/45T JT sprockets 3. JT 428 X-ring chain 4. Air box mod 5. Hawk Digital Cluster 6. Aftermarket IMS shift lever 7. Performance Aftermarket Exhaust 8. 295mm Nitrogen Gas Monoshock, 20W oil front forks
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08-02-2018, 03:27 AM	#8
pete Join Date: Jan 2012 Location: ChCh , NZ Posts: 2,261	Why didn't you turn the cat case into a power bomb since you had it opened up... Is a peice of tube the same dia as the header pipe 1/3 the length of the cat case welded on the engine end of the case.. It traps some of the returning pressure wave and drops the pressure in the header pipe so the next exhaust charge dosn't have to fight so hard to get into the exhaust pipe... .. __________________ 09 XT660R ... 06 TTR250 ... 80 Montesa H6 125 Enduro... 77 Montesa Cota 348 MRR "Malcom Rathnell Replica"... Current resto projects.. 81 Honda CT110... 80 Kawasaki KL250A1... 11 Husaburg TE125 enduro... "sold" along with another 31... Lifan 125 Pitbike.. "stolen" ... KIWI BIKER FORUM...... http://www.kiwibiker.co.nz/forums/content.php All the best offroad rides in NZ... http://www.remotemoto.com/ E-mail... xtpete1@gmail.com
	0

08-01-2018, 04:34 PM	#2
ben2go Join Date: Jun 2011 Posts: 1,335	When opening the air intake or exhaust, the engine will run lean. That can cause burnt valves and other issues. Removing the cat may not be a big deal though. You can cut it out and section in a length of pipe but it needs to be sealed well to prevent running issues. and hot exhaust from burning your leg and pants. Most people either gut the cat or replace the exhaust. There used to be header pipes for sale that would probably be cheaper than a bodge job of pipe and clamps.
	0

08-01-2018, 05:04 PM	#3
ChipToothy Join Date: Apr 2018 Posts: 819	Oh yeah, I’m trying to learn all I can before actually putting hands to it. I don’t see how adding a replacement section is a bodge though. The muffler and header pipe are fitted together with way worse clamps and pipe than the auto store sells. You can get tough as nails everything for cheaper than the eBay kit except no Bashan fitted header pipes to be seen. I just need to find the someone with an exhaust modded on the same bike to hopefully chime in.
	0

08-02-2018, 06:45 AM	#9
Digger Join Date: Jul 2018 Posts: 64	I read somewhere about cutting the cat case in half and digging out the material from each of the case. I plan on using a pipe cutter for a clean cut. This process only requires one weld.
	0