Port And Polish Help!!!

[quadgod440ex]

can anyone describe to me in some detail on how to port and polish a 4 stroke ?? or tell me some where that could tell me where to learn how to.....i have an extra head i wanna learn how to do it to my 400ex if someone could tell me it would be great....i really would like to learn how to.....i no it takes some work but i heard it is alot easier then a 2 stroke and i found a 2 stroke pretty damn easy to do.....well if anyone could help i would appreciate it just let me know guys thanks alot ...

[BigThumper33]

It may seem easy to port a head, but how do you really know your doing it right? I can take a grinder and go crazy and say its done. To do the job right you really need a flow bench.

[quadgod440ex]

that is true but i can port and polish a 2 stroke just as good as any machine shop that i no of around here so i figured id learn on a 4 stroke.....believe me i do take my time i dont like to do something and finish it and not be right.....so like i said if anyone can atleast describe to me how to do it maybe i can learn alittle more as i put pices of it together

[BigThumper33]

no offense but porting a 2 stroke makes all the difference in how it runs. I don't mean you can't do a good port job, but I don't see how you can get max performance for a specific type of riding without a flow bench. They obviously make them for a reason, and big shops use them...so obviously they are a needed.

As far as port knowledge I have I've heard to only port the intake, don't polish....somehow the rougher intake makes the air/fuel atomize better. Not sure if thats correct, but thats what I've heard. As far as exhaust goes, I've heard port it out and smooth her down!

[ChadEXer]

I agree with Big Thumper, you need a flow bench to do the job right!

Improperly ported heads cause way more damage than good...have it done professionally..tryin ta save a buck might cost you several $100 in repairs..

[UglyMotha™]

Originally posted by BigThumper33
As far as port knowledge I have I've heard to only port the intake, don't polish....somehow the rougher intake makes the air/fuel atomize better. Not sure if thats correct, but thats what I've heard. As far as exhaust goes, I've heard port it out and smooth her down!

correct never polish the intake side that is a big no no you actually want to rough it up a little

[TheX1992]

just out of curiousity i have a old 250x head thats of no use for me. same head design as your 400ex just about. i dropped a valve and shes pretty torn up. hey if you wanna see what your abilities are with a dremel and dont wanna worry about ruining your good head ill sell ya mine lol. 25 + shipping if ya wanna give it a try.

[dariusld]

I'm all for doing EVERYTHING yourself. But I don't think grinding away on some head is going to tell you anything. I did the head on my car. All I did was mainly clean up the castings and polish it and opened up the exhaust a little but nothing extreme. But I don't know if I actually gained anything. When I take the head off my 400ex I'm going to do the same. But those experts know alot I don't and they learned the hard way, through experience.

[AndrewRRR]

To tell you how to port a head correctly and properly would take a book, and you still wouldn't have any hands-on experience. If you really want to get into it, go to MMI, and become an intern for good machine shops.
If you have a spare head, it wouldn't hurt to give it a shot i suppose. I would start by port-matching it (intake and exhaust), remove all obvious restrictions, keep the air path as straight as possible. Leave the intake port rough (the turbulence will help keep the fuel atomized in the air at low rpm and prevent pooling. Polish the exhaust to your heart's content. Once you start going bigger with things, you will get into compromises (low, mid, top power tradeoffs).

[thelegendarycd]

i agree with everything said. your best bet would be having a shop do it or get some way to use a flowbench. as for leaving the intake rough and polishing the exhaust, thats exactly what you do. my uncle has built a bunch of motors before and knows how to port and polish and i've seen the heads on one of his motors and the intake is opened up, but not polished while the exhaust is like a mirror.

[quadgod440ex]

if i were to just polish the exhaust side would that give me any difference if i were to jut clean it up abit there is alot of carbon in there now i can see it ....would it be bad t do just one side and not the other..? what can i polish it with and when i polish what is something good to clean out the little particals with?

[ChadEXer]

Originally posted by UglyMotha
correct never polish the intake side that is a big no no you actually want to rough it up a little
Im not for absolute positive, but Im pretty sure that TC polished my intake side too! He has a flow bench and has been doing this about,,,,20 years I think???

[AndrewRRR]

Originally posted by ChadEXer
Im not for absolute positive, but Im pretty sure that TC polished my intake side too! He has a flow bench and has been doing this about,,,,20 years I think???

The only time I've heard about polishing intakes is for engines that run only at very high rpm's for short periods of time.

[UglyMotha™]

chad i don't think anybody that new what they were doing would have polished your intake side it has to rough in order to create turbulance which creates proper fuel/air atomization whatever the dilio with that is, i beleive if the air and fuel isn't mixed up good you'll get air pockets and fuel pockets which then would cause an uneven burn and a loss of power i'm no sure about all that stuff i just said:huh but i'm pretty sure i'm in the right ball park but still i know for a fact that you don't polish the intake side

[ChadEXer]

I dont know, I could be wrong! I was so exited to throw it together I didnt do much looking!!

[L.Vegas400]

i just found this and thought i would go insane reading it all. if you can understand all of it, sounds like you can port pretty good. otherwise you are like me and dont have the slightest

http://www.offroadhaven.com/porting%20a%202%20stroke%20engine/porting%20103%20-%20listen%20to%20everything.htm

[Predator36]

Afraid to make a mistake - pay a pro to do your head. Afraid of failure - dont try.

Me - I would gladly screw up 20 heads just to do my own.

Flow benches - the best engine builders in the world use flow benches for R&D. Few engine builders use them on every head that they port. Many engine builders do not use it on every head since they have long ago learned what makes the port work on a particular engine.

[0240099r1]

ok so we are deleting posts now very well..................

[UglyMotha™]

Originally posted by 0240099r1
ok so we are deleting posts now very well..................

:huh huh:ermm:

[quadgod440ex]

hey guys is it bad if i were to just polish the intake side would that make any of a difference ? or would it be bad...and if not what could i polish it with and what could i then clean it with like a spray or something?? and another question...by taking all the carbon and stuff off of the bottom of the valves and the top of the piston would i see a difference in the performance do you guys think it would run betteR??? and by grinding out the header welds would i be able to tell of any difference at all??? thanks for your time

[thelegendarycd]

polishing only the intake side would be bad and probably not help or possibly hurt. as for how to clean it and if cleaning up the valves and piston, i don't know.

[0240099r1]

Originally posted by 0240099r1
ok so we are deleting posts now very well.................. all i was saying is i posted last night here and it vanished just like that all i said was if you polish the intake side you are hurting yourself due to the fuel sticks to the ports you want the intake rough,and the exaust as smooth as you can get to allow the gasses to escape as freely as possible........

[quadgod440ex]

oop i didnt mean polish the intake side i ment to polish the exhaust side..... would it be bad t just polish the exhaust side and dont port the intake?? would that be bad and if so what can i clean it with??

[AndrewRRR]

You could just polish the exhaust port but I doubt the power gains will be that substantial, especially considering how long it can take to do it.
Most people use some sort of rotary tool like a dremel or professional porting motor with a flex shaft.