Gy-5 exhaust mod

Wild_Alaskan · 03-12-2010, 01:16 AM

Was looking at my gy-5'old header today and noticed that the welds that hold the exhaust tube to the mounting ring are blocking about 25% of the exhaust flow.

A common mod on jap bike exhausts is to take a dremel or file and grind the welds down so the flow is not being disrupted. Also where the exhaust header and muffler piece connect there was a pile of sealant blocking part of the exhaust.
I think with these two blockages ground down you could get a healthy performance boost

Weldangrind · 03-12-2010, 02:34 AM

I found the same thing on TurboT's quad. It's a Zongshen-built Honda pushrod clone at 200cc. Check out http://www.chinariders.net/modules.p...r=asc&start=45

Page four, scroll down a bit.

Wild_Alaskan · 03-12-2010, 02:57 AM

yep that's the mod

hope you don't mind if i borrow your pictures

before

after

Weldangrind · 03-12-2010, 03:14 AM

I'm not sure if porting the exhaust improved anything, but it made me feel better.

stilkikin · 03-12-2010, 02:00 PM

I did the same thing last year. I couldn't feel a difference but like you, it made me feel better. I felt the difference on my old 300ex though when I did this.

03-12-2010, 01:16 AM	#1
Wild_Alaskan Join Date: Dec 2009 Location: Alaska Posts: 914	Gy-5 exhaust mod Was looking at my gy-5'old header today and noticed that the welds that hold the exhaust tube to the mounting ring are blocking about 25% of the exhaust flow. A common mod on jap bike exhausts is to take a dremel or file and grind the welds down so the flow is not being disrupted. Also where the exhaust header and muffler piece connect there was a pile of sealant blocking part of the exhaust. I think with these two blockages ground down you could get a healthy performance boost __________________ Dune buggy build http://chinariders.net/modules.php?n...wtopic&t=14470 400cc lifan build vid: http://youtu.be/20HoU8OK_Y0 other fun: http://tinyurl.com/wildalaskan
	0

03-12-2010, 02:34 AM	#2
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	I found the same thing on TurboT's quad. It's a Zongshen-built Honda pushrod clone at 200cc. Check out http://www.chinariders.net/modules.p...r=asc&start=45 Page four, scroll down a bit. __________________ 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
	0

03-12-2010, 02:57 AM	#3
Wild_Alaskan Join Date: Dec 2009 Location: Alaska Posts: 914	yep that's the mod hope you don't mind if i borrow your pictures before after __________________ Dune buggy build http://chinariders.net/modules.php?n...wtopic&t=14470 400cc lifan build vid: http://youtu.be/20HoU8OK_Y0 other fun: http://tinyurl.com/wildalaskan
	0

03-12-2010, 03:14 AM	#4
Weldangrind Join Date: Mar 2009 Location: Sardis, BC, Canada Posts: 25,977	I'm not sure if porting the exhaust improved anything, but it made me feel better. __________________ 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
	0

03-12-2010, 02:00 PM	#5
stilkikin Join Date: Oct 2008 Location: East TN Posts: 28	I did the same thing last year. I couldn't feel a difference but like you, it made me feel better. I felt the difference on my old 300ex though when I did this. __________________ "The tree of liberty must be refreshed from time to time with the blood of patriots and tyrants." Thomas Jefferson. Never more true. <br /><br />78 Kz650, 79MX80, 04 gy125, 110 rocketa
	0