Looking at the posts on the KK330 thread reminded me that I have allways wanted to get a good explenation of how to port & polish a head from someone who has actually done it or does it routienly.
It seems to me that if you have the tools and confidence then all you would need is a bit of good advice and a lot of time and patience.

I would assume the basic Idea is to smothe out any obstructions to flow, maybe open the passages a bit without comprimising the intergrity of the head. Make sure the intake and exhaust ports match perfectly with the header and carb/intake manifold if the engine has one.

Anyone care to enlighten me? Or is it one of those closely guarded secrets & its trial and error for all amatures?

Cheers Jim

 

Polishing, smoothing, and taking out noticeably rough casting spots is well within the ability of most home mechanics with some patience and a few tools. Truly porting, changing, and enlarging ports is a bit of a black magic art...well, OK...not that bad, but if you don't know exactly what you're doing and why, you'll ruin a head or make the bike run like poo. I'll try most stuff on my own...like doing all the internal shim modifications for the first time on my KLX...but this is an area where I'd even let few head servicing places touch my KLX head. Polishing and smoothing, though, is doable by us mere mortals.

You ever see how many attachments are available for Dremel tools? You can go crazy. I love my KLX300S, but honestly I like the fact that it's pretty darned competent with some relatively easy mods. I had the head off while doing my 300 cylinder, but I wasn't even tempted to dig into the ports. I did lust after those 1st stage Web Cams, however.

 

Porting, and custom cylinder head work is what I do.
What you want to do is pretty much what TNC said. Smoothing just below the valve, where the seat is pressed in, is usually a good idea also. The transition from pressed in seat, to casting is typically rough. What you don't want to do is remove a lot of material, and change the shape of the port. Smoothing, and port matching is a good idea, and can make a difference.

Do you have a die grinder?

 

Thanks for the two posts.

Yes I have die grinder and dremel with a LOT of bits. I like to feel I am pretty good grinding with either although I have never Polished anything other than the glass on a watch(took for ever and was not worth the effort in the end).

I think I may pull the head when I check valves, & stuff at the 12,500 mile mark if I have some time on my hands. Been pretty busy teaching dive classes on the side lately. Its cut into my rideing time and energy. (but the $ are hard to pass up)

Thanks for the tip on the valve seat transition area. I did not think about inside the combustion chamber.

 

correct me if i am wrong,, but,,, my understanding is that an intake runner should not be polished if it is a WET runner. There should be some roughness to it so that the fuel doesn't STICK. similarly the bottom of a racing boat has some texture, and a golf ball has dimples.
I saw that Bill Blue is working on a head that has larger valves in it and ported.
I think the exhaust side is the one that gets polished.
Can anyone confirm or refute???
Thanks,

 

Can't confirm or debate, it's an age old bench racing topic. I've done both on many of the same motors (series 3 rotax) and saw no difference in power, run quality or jetting needed. Polishing the exhaust side and combustion chamber did have a noticeable difference in the amount of carbon build up between rebuilds

Usually when someone paid someone to port they like to see everything nice and shiny, not just the area reworked, also nice to hide the tooling marks and remove any casting lines. Shiny give it that extra bling.

The whole debate about fuel pooling up on the port walls is mostly theory IMO, could be true but a better argument against fine polishing is it's usually a waste of time.

One thought for polishing that I have pondered. All area in nature that are exposed to flow of any kind like water, wind, shifting sands etc, are almost always polished?

I'd say clean it up, but no need for mirror like polish. Unless you do it for a living and know the work will be posted online, then the bling factor will bring more work, LOL