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Message started by savagebob on 10/01/13 at 21:01:28

Title: Exhaust Port Questions
Post by savagebob on 10/01/13 at 21:01:28

Ok so the exhaust port is nasty.

While I've got the pipe off I'm tempted to get in there with the dremel and clean it up. Don't really want to bother taking engine out and taking head off at this stage. But that restrictive lip in there.. I'd love to smooth that out some.

Also what is that weird hole all about?

Before I go in there grinding can anyone tell me how thick the metal is around that restriction ring? Am I save to grind that out?

http://s18.postimg.org/5s2a9oz3t/port.jpg

Title: Re: Exhaust Port Questions
Post by Serowbot on 10/01/13 at 23:16:55

The Tech section has some pics,... but I don't remehttp://suzukisavage.com/yabb2.2/Templates/Forum/default/list.gifmber where...

You can open the port to match the inner diameter of the pipe...(any larger is a waste)... smooth the surfaces (this is good for exhaust, but not for intake)... and you can gingerly round that horizontal "torque hump" that runs across the outlet, but don't get crazy... there's stuff under there...(Err on the side of less on that )...
All this... may add a tenth of a pony... but, I did it... (What the heck... just 'cause I was in there anyway)...
Just concentrate on correcting cheap manufacturing blemishes,... and don't try to outsmart the designers...
Don't get carried away trying gain HP... they ain't much to gain...

;)...

Title: Re: Exhaust Port Questions
Post by savagebob on 10/02/13 at 00:46:00

"torque hump" ?

You mean that horrid ridge I highlighted? That's gotta be a serious restriction in the exhaust flow. The worst thing about porting a head your not familiar with (especially leaving it on!) is grinding out a thin area. So that's why the post.

I did some searching and found this:

http://s22.postimg.org/nzjyd8hk1/after.jpg

Looks like he's taken that ridge right out without issue?

also found this thread which is pretty helpful for my questions actually:
http://suzukisavage.com/cgi-bin/YaBB.pl?num=1275542836/15

Title: Re: Exhaust Port Questions
Post by Oldfeller on 10/02/13 at 03:15:31

The hole is the butt end of the threaded hole of the head stud underneath it (look for the stud and nut below).

That horizontal shelf up at the top is the bottom of the valve seat recess and only has a normal wall thickness of about a 3/16" so don't go crazy on it or you will make you a hole at the edge of the shelf ledge that is facing you.

:-/ (ie. you just bought you a weld up job or a new head).

Just smooth it out with a dremel flap sander, don't try to reshape the thing beyond 1/16" even at the very edge of it.

No one has ever found even one whole HP messing about with the exhaust port & polish routine ..... so if you must, just smooth it up.

Think about it -- exhaust gas is DRIVEN by the piston and MUST exit. Smooth matters little to it as it will carbon up again quite quickly anyway.

It is the intake flow that must be coaxed in under atmospheric pressure vacuum action. Porting applies much more to the intake side than the exhaust.

Title: Re: Exhaust Port Questions
Post by Dave on 10/02/13 at 05:19:36

The ridge can be cut out physically - but at some point it doesn't hurt to leave it as the exhaust pipe is much smaller in diameter than the ridge. The horizontal shelve as OF said is the bottom of the flat area where the valve spings seat.....and you can't cut much of it out. You could round off the sharp edge a little bit.

When I had my engine apart I sharpened and smoothed the divider between the two valve ports, rounded off the shelf a bit, and cut and rounded out the ridge at the port a bit.....and got rid of the casting flaws. I didn't do anything horribly radical....just cleaned things up a bit.

Title: Re: Exhaust Port Questions
Post by justin_o_guy2 on 10/02/13 at 10:07:36

You do NOT want to cut that enough to let a valve sping loose..

Title: Re: Exhaust Port Questions
Post by Ed L. on 10/06/13 at 16:33:35

I ground down the edge of the exhaust port on my '02 till it pretty well matched the inside of the exhaust gasket but left the ridge on the top pretty much alone, didn't want the spring to poke through. Ended up removing most of the ridge you hi-lighted and smoothed out everything. Don't know how much it helped but it was worth a try.