400ex Head & Porting

[chronicsmoke]

I've been looking into trying this for a while and have read a handfull of tutorials and watched some videos on it. I'm going to try my hand at porting. :o

I know it would be much better off in the hands of an experienced professional but you gotta start somewhere. After porting his civic, my buddy I race with wants to try his hand at his YFZ so I figured why not try something myself

my plans are to get a spare head to do the work on while my 400ex is still in good running order so there will be no rush, it will be more of a back burner project. It will be going on my 2001 426ex w/magnum st.2 cam, 10:1 piston, 450r carb, full exhaust & wheelie's 3*key, I've looked around for some help on the 400ex head but there isn't much available. So far my biggest help has been Mixxer's thread on YFZcentral; http://www.yfzcentral.com/forum/32-yfz-powertrain/115722-porting-theory-tools-techniques.html

Some of the theory is a bit over my head, but none the less I think once I am sumberged in the project I'll be able to put the loose connections together. If anyone has experience please post up. I'm weighing the options of + sized valves as well but I'm not sure if they are worth the extra labour and cost.

I'm also looking for a used 400ex head, if anyone has one to sell for cheap ( http://www.atvriders.com/vbb/showthread.php?507815-Wanted-Cheap-stock-400ex-head )

some pictures I've found of the intake side:
1718106907
1718106906

[2001400exrida]

good luck with the project. Mixxer is hands down the #1 most useful person for this sport, he posts any and all information that many builders like to hide. I wish he would post here, but lately he's been on yfzcentral and not on the org as much either. read his fcr thread too it's amazing.

[chronicsmoke]

^Please refrain from posting any more in this thread, I want to keep it on track. Thanks.

Talked with mixxer a bit over on central today and he gave me a few tips..

"the ex machines have what is called a "radial" valve arrangement ... it responds to the same widened floor and gentle radius from runner to bowl... the runner shape makes it a bit of a pain to deal with though...

+1 valves add about 1.5~2hp on a ex setup like yours.... the intakes are soft steel and will probably need replacing when you pull them out..."



I asked a bit more about the radial valve design needing unshrouded or if it is as efficient as it can get, especially for a first timer.

"the radial setup sot of naturally unshrouds itself by the angle opening of the valves... not much to worry about there"

I photoshopped the area that is naturally unshrouded.
1718106908
I'm pretty pumped to learn more as I go,
Thanks again John!

[ben300]

dave, please post and any information you can in this thread. this has been something ive been wanting to try for awhile now!!!

[KKiowaTJ]

I too, Would like to know as much info you can pass along. If I can save money doing it myself, The better!

[MtnEX]

Seems cool...

What is the porting alone worth in numbers put on the board with this motor?

[chronicsmoke]

Thanks for the words of encouragement guys


Seems cool...
What is the porting alone worth in numbers put on the board with this motor?

Well gernerally speaking a quality port job can yeild a solid 10%.. A good port job will really compliment a bigger carb, full exhaust, bigbore ect because it's maximizing the flow. I think if you ported a completely stock bike, the low compression, small bore, restricted intake & exhaust wouldn't let the head shine nearly as it would with a built bike, all of the mods will actually work together and there would be a great performance gain. It's like when I had a bigbore 426 with a stock cam for 3-4 years before I put a stage 2 cam in and the difference was HUGE.. but the bigbore with a stock cam or a stock bore with an aggressive wont compliment each other, but if you add them together, WOW!

What I'm doing actually has the possibility to hurt performance as it is the first time I've ever tried anything like this and I can actually hurt the flow if I do it wrong.

I am getting my hands on a 400ex head ported by a reputable builder so I'll have a 3D model to work with, which should make it a little harder to screw up

[atvrider13]

I did one of mine in a spare motor awhile back. The valve seats can be blended in where they meet the port. There are some harsh ridges also that can be blended in. I also ground the valve guides flush with the port . I also have a spare head i got recently that has some nice porting done to it, I can post up some pics if you would like?

[cheater13]

Look forward to see what the outcome is.

After my big build is done, I want to consider going bigger valves since I drag race a good bit. It's pretty expensive to do though. It'll be my next winter project if anything.

[Blodg]

I am another one who is I interested in this. I cleaned up my ports last winter during my 416 build and a full port job would be next on my list of motor mods. I would be surprised if it would net a 10% improvement but maybe it does (which would be great). I have looked but never seen a dyno chart of a 400EX before and after a port job. I have seen before and after on a 450R and they do gain 10% or more but of course the R has a lot more potential and respond better to motor mods.

[chronicsmoke]

I did one of mine in a spare motor awhile back. The valve seats can be blended in where they meet the port. There are some harsh ridges also that can be blended in. I also ground the valve guides flush with the port . I also have a spare head i got recently that has some nice porting done to it, I can post up some pics if you would like?

Sure I'd be interested in seeing whatever pictures you have. 400ex info like this is limited compared to the 450r

[chronicsmoke]

I got my stuff in to really start on this project.
The ported head;
http://imageshack.us/a/img534/7426/snhc.jpg
http://imageshack.us/a/img36/8353/gqot.jpg
http://imageshack.us/a/img594/8354/hu9v.jpg
The blank head I got (you can see I was playing around a bit before I started taking pics
http://imageshack.us/a/img827/1487/1do1.jpg
http://imageshack.us/a/img844/8974/qazp.jpg
The guides are really pronounced compared to the ported head
http://imageshack.us/a/img33/2639/817r.jpg
And a few after an hour-hour and a half..
http://imageshack.us/a/img594/41/rfnf.jpg
compared to this;
http://imageshack.us/a/img811/7015/rjm4.jpg
It’s pretty tricky to keep a steady hand but I’m enjoying it.

*my imageshack acc is being a dick so let me know if the pics are screwed up.. More to come.

[2001400exrida]

looks good thus far. if nothing else you'll get that rust out of there. did somebody let this thing sit out in a puddle or what, lol.

edit: you will see in the following post after mine that baileygunns is assuming i'm talking about the orange stuff by the ports in the pictures, that's not the case edward, i'm referring to the rust inside the valve chamber, take a looksie in the first photo he posted. also, edward bailey, let's not name call man, that's childish and breeds drama. we don't want to ruin chronics informative thread because you are a keyboard tough guy. that is all.

[Baileygunns]

if nothing else you'll get that rust out of there. did somebody let this thing sit out in a puddle or what, lol.

^^Obviously has no idea whats going on in the pictures, lol.
Poor little troll.... run along now.

[atvrider13]

Sure I'd be interested in seeing whatever pictures you have. 400ex info like this is limited compared to the 450r

Sorry I never got pictures for you, I cant seem to get any that are good. Looking good tho, Are to smoothing the transition fron the seats to the port? There is quite a lip there.

[chronicsmoke]

Sorry I never got pictures for you, I cant seem to get any that are good. Looking good tho, Are to smoothing the transition fron the seats to the port? There is quite a lip there.

Thanks, that's actually reassuring lol. I havent got up there yet, but I have what you said written down haha. I noticed on the ported head that dropped a valve, there isn't really any work done to the combustion chamber.. I think I'm going to do a little deshrouding anyway even though Mixxer said there wasn't much to be done there (I'm just going to smooth out the transition from intake to exhaust a bit) Still hoping to do +1 valves so I think it could use some work there if I plan on going through with that.

If you had any pics of your valve guides I wouldn't mind checking them out!

[atvrider13]

I actually just put that head on mine the other day , I tried to take pics but like i said they were crap. The guides were taken down to the port and blended flush with the port. Not saying that its the best for the guides but its a spare motor that im trying all sorts of different stuff with . If interested pm me. Also if you feel with your finger where the short-side radius is there is quite a harsh ridge there that needs to be blended.

[chronicsmoke]

I actually just put that head on mine the other day , I tried to take pics but like i said they were crap. The guides were taken down to the port and blended flush with the port. Not saying that its the best for the guides but its a spare motor that im trying all sorts of different stuff with . If interested pm me. Also if you feel with your finger where the short-side radius is there is quite a harsh ridge there that needs to be blended.

Yah that's what I'm trying to do is take the calve guide down to where it's minimal (like the 3rd pic I posted last thread) did you remove the brass guide too? I was unsure if I should go that far or not.

[Baileygunns]

looks good thus far. if nothing else you'll get that rust out of there. did somebody let this thing sit out in a puddle or what, lol.

edit: you will see in the following post after mine that baileygunns is assuming i'm talking about the orange stuff by the ports in the pictures, that's not the case edward, i'm referring to the rust inside the valve chamber, take a looksie in the first photo he posted. also, edward bailey, let's not name call man, that's childish and breeds drama. we don't want to ruin chronics informative thread because you are a keyboard tough guy. that is all.
^^Obviously STILL has no idea whats going on in the pictures lol.
Poor little troll.... run along now.

Have a great day Ryan Schaefer!

[2001400exrida]

Have a great day Ryan Schaefer!

I always have a good day Ed. Even when you're trolling me to no end :) Never ever will an internet keyboard warrior who talks smack behind his monitor get to me. You can try and you can continue to ruin threads, but it doesn't phase me :) Here in the real world we do things face to face, so honestly name calling over your dell ain't getting nowhere my man. chronic i apologize for baileygunns 2 post in this thread, they do not pertain to the topic and he has resort to childish name calling. I'll take the blame since i know you hate me, but let's look at it plain and simple who started with the smack talk? i literally dare you to try this on the FB group where you can't hide behind a screen name. you'll be torn apart and ripped up and banned for life. There's a reason you follow me around these forums, it's because you can remain anonymous. You try it on FB and you'll be called out and left to rot.

[ben300]

^^Obviously STILL has no idea whats going on in the pictures lol.
Poor little troll.... run along now.

Have a great day Ryan Schaefer!




I always have a good day Ed. Even when you're trolling me to no end :) Never ever will an internet keyboard warrior who talks smack behind his monitor get to me. You can try and you can continue to ruin threads, but it doesn't phase me :) Here in the real world we do things face to face, so honestly name calling over your dell ain't getting nowhere my man. chronic i apologize for baileygunns 2 post in this thread, they do not pertain to the topic and he has resort to childish name calling. I'll take the blame since i know you hate me, but let's look at it plain and simple who started with the smack talk? i literally dare you to try this on the FB group where you can't hide behind a screen name. you'll be torn apart and ripped up and banned for life. There's a reason you follow me around these forums, it's because you can remain anonymous. You try it on FB and you'll be called out and left to rot.



im not taking sides. since you to cant help yourselves, and i dont want this thread to be ruined, i will be now reporting any post that has nothing to do with this topic as spam, and Baileyguns, i will report and will try and get you banned if you cant be a positive member of the forum. I dont care if ryan has provies useful info, or complete hog wash, you do nothing but instigate and you need to be removed. And if ryan cant help but respond to troll comments, and not let them go, ill seek to have him banned as well. this bickering is ruining this forum.

[LxMxL97]

im not taking sides. since you to cant help yourselves, and i dont want this thread to be ruined, i will be now reporting any post that has nothing to do with this topic as spam, and Baileyguns, i will report and will try and get you banned if you cant be a positive member of the forum. I dont care if ryan has provies useful info, or complete hog wash, you do nothing but instigate and you need to be removed. And if ryan cant help but respond to troll comments, and not let them go, ill seek to have him banned as well. this bickering is ruining this forum.

Agreed as I'll be doing the same...

But now to get back on topic I understand what porting a head does but I've also heard it refered to as a port and polish could someone explain to me the polish part (if there is one) and what would be used to do this?

[ben300]

Agreed as I'll be doing the same...

But now to get back on topic I understand what porting a head does but I've also heard it refered to as a port and polish could someone explain to me the polish part (if there is one) and what would be used to do this?

porting is making the tunnels that runto the valves bigger (this is different than making the valves and valve guides bigger). this is done by grinding and you usually try and match the port to the shape and size of the intake and exhaust manifold.

polishing is makeing that ported area smooth. your head normally has some slag left over from machining and casting and from the porting process. you polish these tunnels to make them smooth. this helps increase the fuel/air flow into the cylinder, thus improving horse power.

[ben300]

hey chronic, heres a good one for ya

http://www.diyporting.com/flowbench.html

[2001400exrida]

polishing is makeing that ported area smooth. your head normally has some slag left over from machining and casting and from the porting process. you polish these tunnels to make them smooth. this helps increase the fuel/air flow into the cylinder, thus improving horse power.

Very true. One thing i would touch up on is that the "port and polish" phrase is really derived from the old 2 stroke days when they ported the cylinders. They would polish those so they were smooth as a baby's butt. They still polish the exhausts very much on these 4 strokes, but typically the intakes are done with a rougher attachment and i know many builders don't actually polish the intake nearly as much for reasons that i don't truly understand but have read it's to help atomization of the fuel. Somebody can verify this. I just know on both of my ported heads my builder did leave the intake a little more rough than the exhaust.

[Baileygunns]

I understand what porting a head does but I've also heard it refered to as a port and polish could someone explain to me the polish part (if there is one) and what would be used to do this?

Porting makes for the best path for flow. You are changing the shape of your intake and exhaust port, hence the term "porting". You want the most air/fuel mixture to make it into the combustion chamber as fast and with the least amount of turbulence possible and you want the exhaust to exit in the same fashion. There's more to it then just opening up the holes to allow more flow. There is a lot going on on the intake side, from short turn radius on the floor, wall shape, roof and valve guides. On top of that, there isn't a constant flow. Every time the valves close there is an abrupt stop in flow whether it be intake or exhaust.

The intake side tends to stay rough to help with fuel atomization. If you polish the intake side of the head you may get a faster flow but the fuel tends to separate from the air and condensate on the smooth surface of the walls (not what you want). Some people will port the head with a burr then go back and polish the runners to find flaws in their work. After any flaws are fixed the runner will be roughed out again with 80 grit or the likes.

The exhaust port side of the head can be polished... There is no worry of air and fuel separating there. What you are trying to achieve is getting the exhaust gasses out as fast as possible. More work on the roof of the port because heat rises and that's where the most flow is going to be. The exhaust port tends to get caked with carbon and hides the polished surface anyhow so its usually a waste of time and really is nothing more then eye candy.

De-shrouding the combustion area helps with flame travel, moving air/fuel in and exhaust out... You're basically taking all the sharp edges around the valve seats and making them go away.

Valve size is going to help with allowing more in and more out... Plus size valves are not always needed. A lot depends on the engine and cam set up. There's no sense putting bigger valves on a stock cam because the cam wont allow the flow. Same with a stock pipe or intake... If they restrict flow in the first place, bigger valves wont help.

The shape of the valve seats can play a role in flow as well.. That's why most do 5 angle cuts apposed to 3... It makes a smother transition for flow.

Valve guides are dictated by the size of the valve stem...These don't normally change with head work. When worn out or enlarged from wear they are replaced. I have heard of instances where people will change the guide sized to accommodate valve from a different engine.

There's a whole science behind head porting but that's pretty much the short and sweet of it... You could read about this stuff for days on end with a simple google search.

[chronicsmoke]

hey chronic, heres a good one for ya

http://www.diyporting.com/flowbench.html

Haha Ben that's already on my To Do list.. Just the electronic part of it is a bit over my head and I really need to spend the time researching that side of it. I think you really need a flow bench if you're getting serious into porting, not saying I plan on getting serious, it's more for my own knowledge.



There's a whole science behind head porting but that's pretty much the short and sweet of it... You could read about this stuff for days on end with a simple google search.

Definitly a science to it haha.. I've mentioned it before in this thread but I want to mention it again, What I'm doing actually has the potential to hurt velocity/flow and make it run worse. It's my first time and I'm not guarenteeing I'll make any more power than my stock head. Of course there is always the potential I pick up a few horse, but without a flowbench, i don't know if it's possible to tell if the port work will make it run better or worse without dyno tuning it after it's been put back together

Thanks typing that out Ed :cool:

[Baileygunns]

I doubt you're going to hurt anything Dave... It's not like you just pretend to know what you're doing, you actually take your time and truly educate yourself before hopping in.

Just be careful around the guide bosses. I know the ones on the 04/05 450 are thin and you can cut right through to the spring seat on the other side pretty quick. Also take note of where your oil passages are so you don't blow into one of those if any are near by.

[ts5413]

I'm curious to know if you are opening up the throat area and if so, what percentage of valve diameter are you using?

[chronicsmoke]

I'm curious to know if you are opening up the throat area and if so, what percentage of valve diameter are you using?

I haven't really touched up there, so far the plan is to go with +1 valves but I don't want to remove any significant amount of material from there until I have that finalized.. from what I've read I'll be shooting for 85% choke area.

Again I'm still a total n00b at this so if any of my info is incorrect please correct me! :o

One thing I just thought about is if I go with +1 valves, should I go just Exhaust or just intake or all 4 corners? This kind of info has become pretty easy to find out for the 450r but I can't find any info on it for the 400s.. Will the stock springs be enough to handle the extra weight of +1 valves?

[LxMxL97]

Another thing about the +1 valves is there a oversized valve/cam combination that's know to work the best together

[ts5413]

You are correct, this info is very hard to find. I've ported one 400 head so far and on my second now. My first head I used 88%. I was thinking that stock it was around 83-84% but I could be wrong. Thought about trying 90% on this head but don't want to lose to much port velocity.
As for valve springs, you're only talking about .040" larger valve so I wouldn't think the weight would be that much greater over a stock valve.

[chronicsmoke]

You are correct, this info is very hard to find. I've ported one 400 head so far and on my second now. My first head I used 88%. I was thinking that stock it was around 83-84% but I could be wrong. Thought about trying 90% on this head but don't want to lose to much port velocity.
As for valve springs, you're only talking about .040" larger valve so I wouldn't think the weight would be that much greater over a stock valve.

How did your first one run? What other mods did you have done to that bike?

I didn't think it would be a signuficant difference but maybe I'll weigh the new valves against the old ones and compare the weight difference before making a decision on springs just to be safe

[ts5413]

How did your first one run? What other mods did you have done to that bike?

I didn't think it would be a signuficant difference but maybe I'll weigh the new valves against the old ones and compare the weight difference before making a decision on springs just to be safe

That one runs very well. Only mods are stage 2 cam, k&n and header welds ground down. It runs right beside my buddy's piped and jetted 450r and will walk away from a piped 400. The head I'm doing now is going on a 426, 11:1, full exhaust and stage 2 cam. With as well as the "stock" engine responded to 88%, I'm wondering if the 426 May like 90%.

[2001400exrida]

Is it true that on the 400ex there is not as much power to gain from porting as there is on the honda 450's? I've always heard that the porting effects are limited and the most hp gained is around 3ish. Does anybody have any dyno's of a 400ex with headwork? dynos for these 400's are impossible to find.

[chronicsmoke]

I havent really had much time since my last post to work on this.. but I found these on my phone from shortly after the last update..

Nothing like working with a little Winter Ale to keep you motivated :p
http://imageshack.us/a/img268/4527/fsk5.jpg

Next three are trying to show how I widened the floor (side opposite to the valve guides)
http://imageshack.us/a/img850/7595/0x58.jpg
http://imageshack.us/a/img18/4233/igvu.jpg
http://imageshack.us/a/img35/6807/37fh.jpg

Not sure if it's correct but this is what I'm doing to make sure I'm taking a uniform amout of material from the ports and keeping them nice and even.. I color where I want to cut and go until the marks are gone ect..
http://imageshack.us/a/img138/8743/5cuv.jpg

So far I'm having fun working on this, definitly time consuming though.

One thing I should get pictures of is the valve guides that I started removing material from. I don't think I'm going to sand them down to the casting, just make them a little shorter and smoother..