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[400exridin121]

from ebay:


400EX Line Bored Header With Custom Chromed Heat Shield



This is a TRX400EX header off of my show bike. The header has been bored at the head end to give it 18% better flow. These come from the factory with a giant weld restricting the flow. By boring and polishing it, you will get better throttle response and more top end power. A must for someone that has a slip on exhaust!


what do they mean by line bored and the weld that restricts the flow? how would i do this to mine?

[400exridin121]

heres a link

http://cgi.ebay.com/ebaymotors/TRX-400EX-Line-bored-Header-with-Chrome-Heat-Shield_W0QQitemZ120066286400QQihZ002QQcategoryZ439 78QQrdZ1QQcmdZViewItem

[JOEX]

To me it sounds like a fancy way of saying 'grinding the welds' to milk some $'s from unwitting buyers.

The 400ex does have a weld bead about 1" inside each header pipe from where it mounts to the the exhaust port. Many, including myself, have ground the welds down flush in an attempt to gain more flow. Weather or not there are any real gains are questionable in my opinion.

In the pic from the link it looks like the welds have not been ground:confused:

[400exridin121]

oh i didnt know what they meant