Exhaust ports on GTR

[kwakrider]

Hello everyone, my name is Quinton from South Africa, been lurking for the longest time, haven’t needed to post up anything till now as some really excellent info is to be had here! I've been biking for 38 years, owned many many bikes...36 in total, starting with a Honda SS 50,lots of 2 strokes,Honda 750-4, Katana's, GSX's, Suz Pre-slings, slingshots, ZZR’s,  ZX12R etc. etc. up to and including a 2009 GTR for the last year. I've done a search, but can't seem to find any information on the exhaust port profile on the GTR…so if there is anything about this please don’t shoot me!!  :)Eventually decided to get aftermarket exhaust header pipes for my BLACK  beauty...when I noticed a weird thing...the exhaust port has a lip on the bottom half that doesn't match the outer diameter of say the exhaust gasket. The pics describe it way better than me! Has anyone matched the ports etc.? I don’t want to mess with something I don’t know about, but surely this restricts performance? Has anyone had this area re-worked? What do you knowledgeable chaps say? 

[curly]

I would recommend you speak to someone with engine/head rebuilding work. That lip is their for a reason and I would not mess with it.
Just my .02.

[pistole]

- as the manifold's branches are inserted into the cylinder head , the ends of the branches will seat onto that shoulder (the lip) that appears in your pictures.

- you may be thinking in terms of flat-face mounting situation where an engine builder would use the manifold gasket as a "template" to work out how much material he could take out from the outlets to match the opening on the gasket.

.

[Steve in Sunny Fla]

Keeping the floor high keeps the port velocity up, and inhibits reversion. Very important on a street operated vehicle. Steve

[kwakrider]

Thanks for the feedback guys,much appreciated!!