Port and polish?

[tcombs0064]

Got bored and decided to have some fun with the dremil on a bad head. i wanted to see what you guys thought. If i messed it up, or if it looks alright.

 

[hawkster0001]

looks like your geeting there, try some high grit sand paper next 400-600 and then so on up from there, does your camera have a macro focus option, that would help alot with the image.

 

[tcombs0064]

took with a Blackberry phone lol. My dremil was getting hot so i just quit for a while, How much should i take off? should i use the Polishing pad after i get done grinding off the metal? First time doing this lol.

 

[duneracerweston]

Do not go past 400 grit sand paper and don't polish it just take the casting marks out of it not a ton of matteiral port and POLISH was some thing you do to a 2 stroke you port the intake and polish the exhaust ports. On a 4 stroke you port the intake and flow the exhaust so the air will enter and it can exhale at high rpm

 

[tcombs0064]

lol pretty much just take all the Grit off of it and make it Shiny?

 

[duneracerweston]

Ya pritty much don't polish it that would slow the bike down litteraly

 

[tcombs0064]

What do the shops do when you get your head ported and polished?

 

[elwood]

What do the shops do when you get your head ported and polished?

Depends on what you want to spend, they go from taking out the casting improfections to D porting the intake for more turbulance. D port = flattening the bottom of the port so it looks like a circle with a flat spot

 

[tcombs0064]

Sounds to complicated to do your self lol

 

[elwood]

Sounds to complicated to do your self lol

Yeah it does, I don't know if they cut it all out or add to it. Just found about about it from a local atv shop/builder

 

[tcombs0064]

Thanks for the info man. you think trying to do it your self will hurt your power?

 

[elwood]

I think anyone with some time and dremel can remove casting flaws, but if you want a high end port job take it to a profesional

 

[MotoArts]

I think anyone with some time and dremel can remove casting flaws, but if you want a high end port job take it to a profesional

X2!

Mine's just one of those basic bench jobs. Figured it can't hurt.
I did mine with a rotary file on an air die grinder (careful, it cuts VERY fast, even when turning the grinder real slow). I removed almost all of the aluminum surrounding the valve guides (called bosses), and only blended the bowls to the hardened valve seats. I did not recountour either port. Followed up the ex. port after this pic was taken with some 100 then 220 and 400 paper by hand (finger), and polished it just a little bit with a small hard cotton buff and white DuPont #7 compound on a dremel. Deck surface was checked for flatness after this pic also.

Chamber was done the same way and polished to a mirror shine by only removing enough material to smooth the surface and not increase chamber volume (lowering compression).

The idea behind polishing the chamber and exhaust port is, theoretically, not to let anything for carbon to stick to and essentially cause detonation.
Porting is what increases the flow, not the polishing as much.

I spent no more than 3 minutes on the intake side. Just smoothed out the casting uglies, the bowl blend, guide boss reduction and that's it. Too smooth of an intake port (again, theoretically) can make the fuel "drop out of suspension" at low engine speeds. In simple english, don't fix what ain't broke! :iagree:

BE VERY CAREFUL NOT TO TOUCH THE VALVE SEATS with any porting device. One nick and you WILL need to (lightly) recut the seat(s), which I absolutely recommend doing after any port job anyways since they're usually beat.

 

[tcombs0064]

looks good man. Notice any power difference?

 

[duneracerweston]

Polishing a 4 stroke kills its ability to mix fuel and air when you got to the 400 grit papper you should stop

 

[elwood]

Polishing a 4 stroke kills its ability to mix fuel and air when you got to the 400 grit papper you should stop

I've always been told polish the exhaust side, never the intake

 

[MotoArts]

Here's an old stock Ford Mustang iron head that I did a long time ago, about halfway through the job. Note the exhaust port is smooth as a baby's butt, and the guide bosses are tiny and shaped like airfoils. The exhaust side was finished with a 120 grit homemade sandpaper roll only, no polish.
Aluminum cuts like hot butter compared to rock-assed cast iron...