porting

[$$$moneyex]

i was wondering what the pros and cons of a port and polish job is. and what it really does. like when you port and polsh what are the mechanics doing?

[TheX1992]

pros = more airflow which means more power.
cons = cant think of any lol....well i spose if you dont rejet than you can have some expensive cons lol



what happens is the mechanic will bore out the intake ports a bit so its bigger. more airflow and stuff. i wana do it to mine.

[L.Vegas400]

port and polish- when your head is cast, the tubes through which your eng breaths are not smooth. when porting and polishing the inprofections are taken away, creating a smother slightly larger air way.

[Nausty]

umm actually the intake ports are supposed to be smoothed. I think it mixes up the fuel better or something. I read about a 4 or 5 page article on porting 2 strokes but I forgot most of it:(

[worm]

how is a amotth intake port on a 4 stroke going to mix gas? id say enlarge the intake where the boot is grind any humps from bad castings and leave the rest bumpy for turbulence...on exhaust...grind the fu** out of it

[SandTrix]

Flowing the head is very very critical. A friend of mine and I have the exact same parts in our EXs except he has an FCR carb compared to my stocker. We both did the work ourselves ane each flowed the head as well. Even though he has a much better carb our EX will still out run his with the same exact paddles and him being a smaller person as well as just a good of rider. So it goes to show that alot of power is in the head of the EX. If you have any questions feel free to ask.

[Sick0]

What did you port. How much gain would you get from just a clean up pot and polish

[SandTrix]

You take the head off and port the intakes and exhausts around the valves. I dont know what your gain would be by a clean up and shine, but I think it would be pretty pointless. If I were going to go through all the work to do it, I would have it done correctly.

[flying400ex]

why dont you just send your stock motor to a builder and when you get it back it will be faster than anyone you built yourself.

[Smoker]

I did my own with good results. I talked to Terry at Marcums and he told me to open the intake 2mm and the exhaust 3mm. I took the valves off, took a permanent marker and marked all around the ports then measured it and scribbed to the edge of where I wanted go. That sets the guideline to grind to then I got inside the ports and started opening them up. I was careful and didn't go real big in any one spot until I was able to see it was going to be even. I made the center part of the intake nice and sharp and took the bottom edge of the port down so it didn't curve so sharply. I didn't remove a lot around the front of the guide although it would have probably benefited but I'm no pro, I just tried to imagine the best possible path for air to flow. The ring the the valve seat is on needed a lot of cleaning up since it really sticks out. You have to be extra careful not to mess the valve seat up though. The exhaust ports were the same thing essentially. I polished the exhaust port with 400 then 800 grit wet sand paper and polished the intake smooth then took dry 400 grit and pressed hard and moved in a swirl fashion to leave small grooves so when fuel and air come across it mixes better. I matched the manifold and exhaust to the ports and put on a 39mm FCR. I did all my motor work at the same time and have been pleased with it, up until I broke my arm :p

[ratmotor99]

porting is taking all the minor defects out of the intake and exh.. there is minor casting defects if you will, like little speed bumbs the air hits it and causes it to bounce around just alittle, if you take them out it causes the air to move more stright in to the engine. polishing is in real guy terms LOL with out going doctor on you LOL, is making everything smooth like glass, when the air comes in it tumbles around when its stock.

pros are more Hp and tq

cons are if you mess up your done for the day
and its time to buy a head (just don't hit the seat where the vavle sets PLEASE

there are many ways to port gasket = taking a gasket and marking it out the size of the ports

CNC = send it off to have the tool and die guys make it FLOW. i have sent many heads out to get CNC, on cars it $$. but well worth the $$ plus if its a good company they will folw test it before and after to tell you what kind of CFM's you made in doing it..

i haven't really seen many shops in the mag(dirt wheels etc..) that do cnc stuff for quads, but i'm working on a program to start doing it, if i can get a shop together LOL


Rat

[airheadedduner]

(quote)when the air comes in it tumbles around when its stock.(quote)
You are not supposed to polish the intake, it needs to be rough. Otherwise it won't flow right and you will actully lose a LOT of power buy polishing the intake. Does anyone know anything about porting 2 strokes???

[Smoker]

Originally posted by airheadedduner
(quote)when the air comes in it tumbles around when its stock.(quote)
You are not supposed to polish the intake, it needs to be rough. Otherwise it won't flow right and you will actully lose a LOT of power buy polishing the intake. Does anyone know anything about porting 2 strokes???

I didn't really polish the intake as much as clean it up after grinding. I did the dry sanding to make sure it wasn't smooth, you also don't want the intake smooth because fuel will bead up and lay there instead of coating the metal so air/fuel will flow across it. CNC porting would be awesome. I would only regard what I did as a play porting since there's no flowbench reading to confirm improvements. There weren't a ton of casting flaws like I have seen on some 2-strokes (much more complicated cast) except the liner they press in for the valve seat, there's a giant lip there that I'm sure benefited to smooth out without sacrificing strength to the seat. I've seen some porting specs for 250r's on the internet but unless you really know how to read and follow them I would send a 2-stroke cylinder off to get done since they are much more tempermental other than cleaning up casting flaws, polishing a little and matching the ports to the gasket. This my opinion in what have learned in the last few years. :p

[SandTrix]

If anyone is interested I build alot of R motors in our area and have had the fastest drag R at LS for quite awhile now, and just got interested in flowing heads on 4 strokes. I have built my personal EX and I cant be more happy with the results. I have been charging $150 to flow the head of the EX. If anyone is interested in having some work done or some recommendations I would be more than glad to share the knowledge I have. It really really isnt necessary to pay $375 for a flow job on a 4 stroke. Like one said earlier, it isnt like a 2 stroke where u have to have a great deal of knowledge. I would even be glad to share my knowledge of 250R porting if anyone has a question or is interested in having some work done or would like some references.

Since your in the giving mood how about I send you my head and you port it and throw it on the flow bench for free and I do a full write up report on how good of job you did and that everyone should send there heads to you for a port job..:D :D J/K

[skemp]

SandTrix, you have a PM from me.

[Sick0]

How much horse power would you see from the porting.

[2qk4u]

sandtrixx you have a pm from me also. got a ? for you