Grinding out the exhaust port

When i changed my exhaust i noticed that the gasket and the port didnt match up.

You can easily feel the ditch that is behind the exhaust ports wall facing the header.

So when i installed my header and system i grinded that down a bit to look more like the size of the exhaust gasket (but not all the way)....

I had to smooth out the FMF header inside also because that was actually smaller than original header (surface that face gasket) so that this surface match up more properly also.

But be careful. The welding is done on the inside of that pipe and U dont want that to crack.

I dont know if this was either good or bad but in my thinking it must have been good. The port opened up atleast 1/5 inch ( or about 5mm) in diameter (if not more).

Put a sponge into the exhaust ports (so U easily can pull it out later...) so u dont get all the aluminum leftovers into your engine.

Then use some airpressure to blow the rests out. And take then the sponges out and fire up the engine so any particle left blows out.

DONT try this if you are unsure in this kind of operations, and dont blame me if if something goes wrong....

So... good or bad??

Interesting.

I'll have to take a good hard look if I ever get to the point of replacing the whole exhaust.

I can't say whether it's good or bad. It seems like a good idea, but without a dyno available for a before and after comparison, who knows? I don't know enough about exhaust systems to speculate whether it should make an improvement due to less restriction, or if that was there to increase exhaust gas velocity. I'd be very curious to see dyno results though.

I did this to my KLR header. The KLR is pretty pokey, but it gave me piece of mind that I was improving flow for nothing more than a few minutes of work.

Modern 4 stroke car engines are DESIGNED to have a step out of the head, and into the header....

Dont know about the WR, as its not a multi-cylinder that uses exhaust pulses in the same way, but you never know really how its been designed!!!

http://www.ehow.com/way_5568639_diy-porting-exhaust-manifolds.html

These lines feels like a YES to me anaway....
But yet they say it may not be effective everytime..
To grind out to match the gasket semes like a good idea they say anaway. both port and exhaust header

http://www.advrider.com/forums/showthread.php?t=329337&page=1304

Heres another guy that has done some work on the exhaust port.
The picture he shows is when port is grinded all the way against the gasket.
The port does not look like that stock.

It's pretty common in cars. "Gasket Matching". I don't think I've ever seen a dyno to prove it's effective in cars, but a smaller gain shows a larger percent on our bikes.

In theory it should increase high end power at the expense of a little low end torque.