Port and polish

[lil_fmx_kid]

What are people's thoughts on porting and polish crf heads?

 

[my67xr]

definately worth it
will gain better flow, giving better top end
more torque, making more power from midrange

do it if you can.

 

[lil_fmx_kid]

I'm convinced! Already polished the intake manifold and match cut it to the carby and spacers. Polished the exhaust port on the head. Just wasn't sure what to do with the intake port since I'm already in that far

 

[Karlos247]

Don't polish the intake. Leave it rough

 

[8r3nd0]

Yeah if you do polish it only do the bottom side of it and leave the top the roughness helps atomize the fuel and aids in combustion.

 

[my67xr]

polish the outside of the manifold for a bit of extra bling!

 

[GooseMan]

With that hole do not polish the ports thing is it actually proven?
My mate who used to race and is a diesel mechanic told me to polish it. Now I'm stuck on the fence as whether or not to polish my xr600 head or not the ports have allready grown in size by quite a bit just holdin back on the polishing for now.

I was thinking that maybe it only beads if the ports are mirror shiny and smooth??

 

[zwebx]

With that hole do not polish the ports thing is it actually proven?
My mate who used to race and is a diesel mechanic told me to polish it. Now I'm stuck on the fence as whether or not to polish my xr600 head or not the ports have allready grown in size by quite a bit just holdin back on the polishing for now.

I was thinking that maybe it only beads if the ports are mirror shiny and smooth??

I believe its been done and tested on a flowbench..
otherwise it would have been shot down every time its been posted

 

[timeeh]

With that hole do not polish the ports thing is it actually proven?
My mate who used to race and is a diesel mechanic told me to polish it. Now I'm stuck on the fence as whether or not to polish my xr600 head or not the ports have allready grown in size by quite a bit just holdin back on the polishing for now.

I was thinking that maybe it only beads if the ports are mirror shiny and smooth??

the first time i heard about it was from a guy who designed race engines, he told me to imagine a car bonnet that had just been polished and then driven in the rain, you will notice the water beads then runs off, whereas if the bonnet has not been polished each little bit of rain just runs off without beading (if that makes sense) this lad deffinately knew his ****.

 

[GooseMan]

Yeah that makes sense. Although the head is quite porus so just smoothing it off should be ok?

 

[my67xr]

yeah, just run a coarse grinding stone up and down etc through it.
most $2 shops sell the sets cheap, and if you dont have a die grinder, just use a drill
i like my exhaust ports polished mirror finish though.

 

[zwebx]

I did my head with a rough diamond stone and then finished it with heaps of time and sandpaper they come up pretty nice

 

[GooseMan]

I used a flappy disc thing, worked well.

 

[lil_fmx_kid]

Yeh you can polish the inlet manifold but not so much a good idea to do the inlet port or the fuel won't etermizer and will run like a dog. Easiest way I found was start with a die grinder burr for the 1st cut then work down to a stone

 

[zwebx]

Yeah the idea is is that rough, the air sticks to the port a bit so to speak and the other air can glide over it with minimal friction so more flow...
the only reason you polish the exhaust is to reduce carbon build up (or remove it almost if you did a good job)

 

[Cordogs]

I'm no spanner spinner but this looks polished to me?

 

[my67xr]

the combustion chamber area is all polished, but not down and inside the runners of the ports.
by the looks of it, they are just finished off with a flapper wheel maybe ?

 

[Cordogs]

Na mate that's polished, those flap wheels can get it pretty fine but not like that.

Plus there's now way some one would get that kind of finish with a die grinder! I know your good mate but no ones that good. That's cnc n elbow grease!

 

[my67xr]

that work in your picture isnt cnc.
here is an old Ducar head i spent an hour or so cleaning up.
die grinder, carbide burrs, and flapper wheels were used to grind it back, open it up, then finished with flappers.
the combustion area is polished on this head, but the runners of the ports are just finished with a flapper wheel.

 

[my67xr]

cnc ported heads are pretty much perfect once done,
the ports with be perfect, equal sized/smooth in all areas, depending on how much time they spent programming the mill
you don't need to clean them up with sandpaper after having them ported.

here is a cnc ported head-