port & polish

[jordan_m6]

any body done there own port & polish. if so i need some tip before i consider doing my self. i am not a total idiot so i know not to port too much

[Eddiesanders250]

4 stroke or 2 stroke? I would port a 2 stroke before i did a 4 stroke. I know some guys who have ported their own head. turned out nicely, ive never done it.

[jordan_m6]

4- stroke its a 400ex.

[stc416rider]

yea i was wonderin about this 2

i wanted to do this to mine but i dont want to ruin n e thing

[jordan_m6]

you really cant ruin anything unless you dig too much.

[kc8pnd]

When I had my 300ex head off i took a dremel tool and shaved off all the "ruff" areas from the casting, can't tell if it helped cause of the new 11:1 piston.

[jordan_m6]

port & polish is more of a safety precaution than any thing. yea it allows more flow which allows cooler temps. at the same time the cool the motor the more power it gives. heat is the enemy.

[wcbomb]

Sorry, but a port & polish will not make a motor run any cooler. More air = more power = more HEAT. On a stock motor you should only port & polish the exhuast side. You will notice all thru the RPM. If you do the intake you will lose alot of bottom end power a little in the mid and not gain much on the top. Get a high compression piston and a cam. Then you can port the intake with great results.

[xx3003xrdrxx]

Porting isnt somehting just some random nobody can do. It takes alot of practice to get it right. If you do it by yourself you most likely will make it run worse . Actually , I garuntee you it will being as you dont know how to do it or what to take off and all. I would NOT do it myself if i was you .... Just my 2 cents though

[Eddiesanders250]

I agree. I wouldnt touch it send it off to let a professional do it.

[F-16Guy]

I would do a four stroke before a two stroke. Port shape and height are critical on a two stroke, since that is the equivilant of the cam on a four stroke. If you just clean things up and don't reshape things too radically, you should be fine. Just make sure you leave the intake ports with a rough texture.

[jordan_m6]

ok so i have talked to some guys and they say just to clean it up dont even bother taking any out. i dont know what i was thinking i was thinking V8 and porting the coolint passages. was a lil drunk. like i am now

[chevrolet486hp]

Its reily easy.Its easyer than taking the engine apart. Just the sharp edges . Use a sand stone on aluminum . Use carbide cuters on cast .All you realy want is the quikest way to get air & fuel past the INT. valve & EXH. out. Porting will pay off if you get more CFM. CARB. & JET KIT then modify or get new EXH. If you dont get a new cam or high compresson piston ther will be no more heat than before the modifictions. More HP & TOURQE threwout the rpm range at 200 to 300 more RPM.

[2muchquad]

i have been doing my own for years,i will put my 385ex up against any 4 stroke tech or sparks built engine out there.a 300ex isnt exactly high tech.those guys had to learn just like i had to.i would never pay some clowns 3 or 4 hundred bucks to touch my motor.no way.i pay for my crank rebuilds thats about it:)

[Cody_300ex]

Ive done 3 300ex heads. All had great gains and sounded 2x better. One the only mod was porting & polishing and it pulled twice as hard mid to top. Like someone else said leave the intake rough, to help fuel atonamisation(sp). I also polished the exhaust side ALOT, I mean chrome like. I did all of this with a dremal tool....

[2004exrider]

Sorry to ask the first dumb question:o , but can you take to much off the exhaust ports and lose power like you would on the intake side?

Jimmy

[travhimself]

first things first!!! take it to somebody witha flow bench!!!! if you have no educated experience leave it to a pro!!! and second never polish anything!!! maby a a little cleaner on the exhaust side but never let anyone tell you to polish on intake side!!! i can do 4 strokes on the bench for 400.00 and send you the numbers back before and after!?!?!? i have been gaining about 12-15 % on the 06 trx450 ;)

[jordan_m6]

wow you really sound like a dick. im not some dumb *** i dont know how many times i have been inside an engine, so this is just to get some pointers like not polishing the intake side that is a good thing to know im just trying not to spend $200 for some other average person to do it for me. god for bid if someone would like to learn new tricks. if i screw something up o well looks like class 1 is over and time to start class 2

[travhimself]

not trying to sound like a dick just trying to save you some aggervation, well so much for that! otherwise dont ever try a bike with a head that i have ported youll be embarrased :o

[jordan_m6]

Originally posted by 2004exrider
Sorry to ask the first dumb question:o , but can you take to much off the exhaust ports and lose power like you would on the intake side?

Jimmy


yes you can over port & polish, you should not go any bigger than the size of you exh. cause then you are making it harder to flow. you mainly want then to run flush. the real power comes from oversized valves.

[travhimself]

Originally posted by jordan_m6
the real power comes from oversized valves.




wtf thats friggin the stupidest thing i have ever heard,

[jordan_m6]

ok then how many people sell kits that dont have oversized valves NONE you want more power you get a port and polish with over sized valve. you are starting to making your self look like an @$$

[ZRFRACING22]

i dont want to sound stupid but im learning, what do i want to do first on the exhaust side with a dremal, do i use a sander bit or more of a polisher, also what should i use on the intake side

[Cody_300ex]

Originally posted by ZRFRACING22
i dont want to sound stupid but im learning, what do i want to do first on the exhaust side with a dremal, do i use a sander bit or more of a polisher, also what should i use on the intake side

I started out with the cylinder grinding stone to take material out and used the sanding things to smooth it out and polishing to polish it up.

[kc8pnd]

I was reading a website that was linked off this site. The guy said oversized valves don't do much for the motor. Can't remember the site or where it was post.

[2muchquad]

The guy said oversized valves don't do much for the motor.

oversize valves arent really needed for the 300ex.the mechanical rpm limits of the motor are well exceeded with the rockerarm setup before one could get the full benefit of oversize valves.this is clearly just a case where a lot of people believe what they "heard" rather than what they see.i dont care what these aftermarket engine wannabe builders say:)

[Cody_300ex]

Originally posted by 2muchquad
oversize valves arent really needed for the 300ex.the mechanical rpm limits of the motor are well exceeded with the rockerarm setup before one could get the full benefit of oversize valves.this is clearly just a case where a lot of people believe what they "heard" rather than what they see.i dont care what these aftermarket engine wannabe builders say:)

I was told by 3 Very well respected engine builders that if you want to run up front in the Youth Production Class, you going to HAVE to have them. That the stock size valves are just to small on a built engine, and it restricts airflow.

[jordan_m6]

I believe oversized valves really make your ride come a live with slight mods. like a 12:1 440 with a stroker kit if you put oversized valves on a stock bike you really cant expect much. but i could be wrong people told me that i wont feel the power of my cdi box but you can in the shifts

[jordan_m6]

Originally posted by Cody_300ex
I started out with the cylinder grinding stone to take material out and used the sanding things to smooth it out and polishing to polish it up.

you use a dremel or an air grinder

[400EX29621]

I recently ported the head on my 400ex as I was upgrading it to a 440. It was relatively easy to do, but it took 4-5 hours. The intake side of mine was really rough (really bad casting line, and necked a down around the valve guide). I also opened the exhaust side quite a bit too.

I used a dremel with some 60grit and 150 grit sanding drums (60 to remove material and the 150 to smooth it out). I also had a local machine shop do a nice 3 angle valve job. It was worth the extra $25. If you do have a valve job done, be sure to lap the valves with lapping compound (about $3 for a can) then finish it up with mothers wax.

I tested it out this weekend and ran even with my buddy YFZ450 in the dirt. He did out pull me on the road by about 2 lengths on the road, I just ran out of RPM's. I just ordered the 16t front sprocket and plan on a white bros rev box. I will try againg this weekend to see if these help out.

[jordan_m6]

what you do to mod your headpipe 400EX29621

[hondardr4life]

Originally posted by xx3003xrdrxx
Porting isnt somehting just some random nobody can do. It takes alot of practice to get it right. If you do it by yourself you most likely will make it run worse . Actually , I garuntee you it will being as you dont know how to do it or what to take off and all. I would NOT do it myself if i was you .... Just my 2 cents though

What are you talkign about. I did your 300 motor and it had a shat load more power. I did port it out a little too much though because that quad was lacking in bottom end. It would have been perfect for a 330.. I wouldn't do it again though. You will get the most performance by letting a pro do it. And for whoever said they'd rather do a 2 than 4 stroke, I would have to strongly disagree. 2 strokes are A LOT more touchy to port jobs than 4 strokes.

[400EX29621]

If you remove the stock head pipe, you will see what looks like a thick washer welded into the headpipe where it bolts up to the exhaust ports. The ID of the pipe is about 20 mm here. I took a die grinder and ground that insert out to the wall of the pipe. It opened the id up to about 28mm. This really made a difference with the stock engine with the K&N filter and lid.

[jordan_m6]

so i have a 11:1 std. bore piston im ganna try that to see what happens but i will check with honda if they sell those just in case i dont like what it does. if they are replacable

[PismoLocal]

Ive been looking on the ebay and i found a guy who does porting for $250 i cant say ne thing about his work but he does have a lot of positive feedback. Check it out HERE (http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=4615479285&ssPageName=STRK:MEWA:IT)

[pit/wood]

It aint rocket science,spend a bunch of time researching the subject online.Understand the principals,get advise from someone you trust,buy the right tools(realy important!)and learn as you go. Just dont screw anyone along the way by learning on thier machines, unless they know the score. And most of all,ride fast!just my opinion,and like alot of opinions, I am sure it stinks to someone.

[2muchquad]

I was told by 3 Very well respected engine builders that if you want to run up front in the Youth Production Class, you going to HAVE to have them

tell ,me this is a joke right? i would think that if a rider was in good shape and he was fast then he would be good to go.oversize valves wont be the difference,i can guarantee you that.:) i saw with my own eyes a few years back a kid by the name of Nathan Dallas smoke banshees and 250rs with a cr80 motor in a blaster.yes sir ree;) he must have been given up 3 times the hp,rider skill will put you up front

[Cody_300ex]

Originally posted by 2muchquad
tell ,me this is a joke right? i would think that if a rider was in good shape and he was fast then he would be good to go.oversize valves wont be the difference,i can guarantee you that.:) i saw with my own eyes a few years back a kid by the name of Nathan Dallas smoke banshees and 250rs with a cr80 motor in a blaster.yes sir ree;) he must have been given up 3 times the hp,rider skill will put you up front

Call Any big time engine builder and they say it...

[400EX29621]

Hey Jordan, what type of piston are you installing (wiseco, Namura???). I installed the 11:1 wiseco in mine. After doing some reading/studying the piston, I found out that the head gasket thickness makes all the difference in 9:1 to 11:1 compression ratios.

Before installing the head after replacing the piston, rotate the engine to TDC. You can check this by removing the small plug at the top of left side crank case cover and rotating the engine until the flywheel mark (with the T). With the head gasket off, measure the position of the pistion with respect to the top of the sleeve. Then measure the thickness of your head gasket. Using the wiseco piston, you will want about 0.025 clearance from the top of the piston (at TDC) to the top of the head gasket (minus about 10% of the thickness of the head gasket that it will compress after you lock the head down).

The piston in mine came about 0.020 above the top of the sleeve, so I went with a 0.050 head gasket (that was approx 0.045 when compressed) that left 0.025 between the piston and the head.

My compression test verified the CR at 10.8:1). In order to get the right thickness gasket, call Cometic (www.cometic.com).

[jordan_m6]

you have any idea what the stock head gasket is. thats what i had to put back on the cometic one that i got ripped. but after break in i will change it.

[jordan_m6]

you have any idea what the stock head gasket is. thats what i had to put back on the cometic one that i got ripped. but after break in i will change it.

[JOEX]

Originally posted by 400EX29621
Hey Jordan, what type of piston are you installing (wiseco, Namura???). I installed the 11:1 wiseco in mine. After doing some reading/studying the piston, I found out that the head gasket thickness makes all the difference in 9:1 to 11:1 compression ratios.

Before installing the head after replacing the piston, rotate the engine to TDC. You can check this by removing the small plug at the top of left side crank case cover and rotating the engine until the flywheel mark (with the T). With the head gasket off, measure the position of the pistion with respect to the top of the sleeve. Then measure the thickness of your head gasket. Using the wiseco piston, you will want about 0.025 clearance from the top of the piston (at TDC) to the top of the head gasket (minus about 10% of the thickness of the head gasket that it will compress after you lock the head down).

The piston in mine came about 0.020 above the top of the sleeve, so I went with a 0.050 head gasket (that was approx 0.045 when compressed) that left 0.025 between the piston and the head.

My compression test verified the CR at 10.8:1). In order to get the right thickness gasket, call Cometic (www.cometic.com).
How did the compression test verify the compression ratio?

[400EX29621]

The stock head gasket on mine was 0.040 inches thick. But the biggest thing I noticed the old piston on my EX (before resleeving and decking) came to about 0.020 below the top of the deck, resulting about 0.065 in clearance. By bringing that clearance down to 0.025, the CR went up to 11:1.

I used a compression gage the I purchased from a local autoparts store to check the CR ratio. Its about $40, just have to make sure it comes with the correct insert for the 400ex plug

[pit/wood]

Seems to me the only way you could know you actual ratio is to know just how many cubic inches your combustion chamber contains.correct me if thats wrong.

[JOEX]

Originally posted by 400EX29621
The stock head gasket on mine was 0.040 inches thick. But the biggest thing I noticed the old piston on my EX (before resleeving and decking) came to about 0.020 below the top of the deck, resulting about 0.065 in clearance. By bringing that clearance down to 0.025, the CR went up to 11:1.

I used a compression gage the I purchased from a local autoparts store to check the CR ratio. Its about $40, just have to make sure it comes with the correct insert for the 400ex plug
I'm no expert but I don't think using a compression guage is how you find out what the compression ratio is.

The thickness of the head and base gaskets do play a definate role though along with the cc'ing the head....

http://www.hotrod.com/techarticles/54258/

[400EX29621]

A automotive compression gage is used to check the compression ratio of an engine. Granted, I dont know how precise a $40 gage from autozone is, but the reading I got we right where I expected it to be.

[JOEX]

Originally posted by 400EX29621
A automotive compression gage is used to check the compression ratio of an engine. Granted, I dont know how precise a $40 gage from autozone is, but the reading I got we right where I expected it to be.
Please explain how you determine the compression ratio using a compression guage.

[400EX29621]

You can calculate you "theoritical CR" if you know the total volume that is present when your cylinder is @ TDC and knowing the bore/stroke of your engine (std bore of 400EX is 85mm and stroke is 70mm). The total cylinder volume @ TDC is made up of the head volume (38cc on a 400EX) plus the volume between the top of your piston (@TDC) to the top of your head gasket (calc by (3.14*bore*bore/4)*piston clearance). This is valid if you have a flat top piston. The calculate your cylinder volume and divide it by the TDC cylinder volume, thats your CR.

The thicker your head gasket, the lower your CR is going to be.

[pit/wood]

So which way did you determine your c.r..the theoretical one or the actual one? Realy,I would like to know.

[JOEX]

Originally posted by 400EX29621
You can calculate you "theoritical CR" if you know the total volume that is present when your cylinder is @ TDC and knowing the bore/stroke of your engine (std bore of 400EX is 85mm and stroke is 70mm). The total cylinder volume @ TDC is made up of the head volume (38cc on a 400EX) plus the volume between the top of your piston (@TDC) to the top of your head gasket (calc by (3.14*bore*bore/4)*piston clearance). This is valid if you have a flat top piston. The calculate your cylinder volume and divide it by the TDC cylinder volume, thats your CR.

The thicker your head gasket, the lower your CR is going to be.
How do you convert the PSI reading of the compression guage to the compression ratio?

[400EX29621]

Compression ratio could be calculated by :
Cylinder Pressure / Atmospheric Pres. = CR

The cylinder pressure is measured by the compression gage and atmos pressure (at sea level is 14.7 psi)

[jordan_m6]

my 11:1 piston has a raised flat top so if i were to go with a thinner gasket wouldnt that be too close.

[JOEX]

Originally posted by 400EX29621
Compression ratio could be calculated by :
Cylinder Pressure / Atmospheric Pres. = CR

The cylinder pressure is measured by the compression gage and atmos pressure (at sea level is 14.7 psi)
I could be wrong but I don't think that is how the compression ratio is figured.

I'm not so good at explaining things but I belive it has to do with the difference in volume of the cylinder at TDC and BTC. Atmospheric pressure and cylinder PSI are not factors in the equation.

[jordan_m6]

(cylinder volume at BDC)/(cylinder volume at TDC).

just looked it up on google and this is what i found Compression Ratio Calulator (http://www.turbofast.com.au/Tfcomp.html)

[pit/wood]

If you have a displacement of 4 cubic inches(total volume of cylinder and combustion chamber combined when the piston is at its lowest point)and a combustion chamber volume of 1 cubic inch(piston at tdc,the remaining area is your actual combustion chamber regardless of the type of piston you have).then the ratio of compression is 4-1.you start out with 4 and you reduce it to 1. To determine these takes more than a compression gauge I believe.

[desertrats]

agreed

[travhimself]

there are way too many variables,YOU CANNOT FIGURE CR BY KNOWING CYLINDER PRESSURE!!

[desertrats]

I was/am agreeing with pit/wood

[400EX29621]

Pits and Jordans cal of CR is right, Vbdc/Vtdc = the CR
There is also an equation called the ideal gas law which states
P1V1=P2V2 where P is pressure and V is volume
or
Ptdc*Vtdc=Pbdc*Vbdc (where the pressure is measured as PSIabsolute )

therefore (for the math impaired) the

CR = Vbdc/Vtdc = Ptdc/Pbdc

[pit/wood]

When performing cyl.head work on old V8 engines it was required to know what the volume of each comb. cham. as it was before and after your work.we called it c.cing the head. It is the only way to keep the compression the same in all the cylinders.A piece of plexiglass(1/2" thick is best)cut it out a little bigger than your cyl head comb,cham.use a gasket to seal it.remove the ceramic portion from an old spark plug and use it to fill the co.ch. with a syringe(marked in c.c.s). Remove and measure the contents,then grind and polish till you get them all the same.then you get into templetes to use for porting and it gets real deep after that.How ***in fast you wanna go??????lol:devil:

[JOEX]

Originally posted by 400EX29621
Pits and Jordans cal of CR is right, Vbdc/Vtdc = the CR
There is also an equation called the ideal gas law which states
P1V1=P2V2 where P is pressure and V is volume
or
Ptdc*Vtdc=Pbdc*Vbdc (where the pressure is measured as PSIabsolute )

therefore (for the math impaired) the

CR = Vbdc/Vtdc = Ptdc/Pbdc
I'm quite ignorant on Laws and Theory's and the like. Instead of throwing some formulas could you dumb it down using everyday terms so that average ATV rider would understand how a compression guage can be used to determine the compression ratio of an average ATV motor in real world conditions.

Thanks:)

[Eddiesanders250]

Macdizzy explains how to calculate the Compression Ratio, but everytime you click on it, no server.

[pit/wood]

Its real simple,but the precise compression ratio in the real world means nothing in a single cyl engine.A compression gauge is not a tool that is designed to tell you the actual co.ratio.It is a diagnostic tool,and that is all.its best used by you and me to learn what pressure is developed in your engine after it is built and broken in.Then you can use that baseline reading to diagnose any problems that might be related to a loss of compression in the future.In the case of multi.cyl.applications a comp.gauge can be used to determine any great difference between cylinder pressures.I guess to answer your ? as to how you can determine you c.r. using a comp. gauge,you cant. If you realy need to know then I think you can do it on the machine but it will take a bit of screwing around.you need an old plug(remove the ceramic portion and shove a piece of vac.line into it.Remove your camshaft and make sure while you are turning the engine over by hand that the chain doesnt get wadded up.Get your piston at bdc.then fill your cyl with auto trans fluid to the end of the tube recording precisly the amount of fluid it takes to fill it.using a ratchet on your crank nut slowly bring it up to exact tdc catching all the fluid as it comes out.the amount you put in is your total cyl.capacity.The amount you take out is your total displacement.the difference is your comb chamber capacity.If you have a dissplacement of 400ccs,and a comb.chamber that holds 100ccs,then your comp.ratio is 4-1.Are we havin fun yet?all of this realy,in my opinion,is not needed unless you just want to be able to say,yep,I have a powerbong pipe with a billybob piston that gives me a 13.164 to 1 compression ratio.Or you have a multi cyl engine and you are trying to diag. a problem like a cyl that is runnin a little richer or leaner that the others.We all know its not about what you got,its about how you use it.

[400EX29621]

I am not sure why you would use an old plug and vacuum line. The compression tester that I used had an insert that was the same thread as the plug, therefore just screwed into the plug hole. It also held the peak cylinder pressure, so the cam didnt have to be removed. I am not sure what type of rocks and sticks you guys use to work on engines, but maybe you need to look for tools outside of grand dads garage.

Regardless if you believe it or not, I calculated the CR using the known bore&stroke, cylinder head volume and calculated what gasket thickness I needed to get the compression ratio I wanted. I then confirmed that using the compression gage.

[pit/wood]

LMFAO,your too funny . There is a huge difference between a theoretical compression ratio that is achieved by using charts and calculations.All I did was explain a method to determine the exact compression ratio.I have used compression gauges for over thirty years. You stated that you confirmed your ratio at an odd figuire of 10.8:1. I can appreciate your ability to calculate your ratio using the methods you do,and they may be in the ballpark.but stating that the combustion chamber of 400ex is 38 cc is going a little far.I have worked on a couple of 400ex cyl.heads and they are no where near that precise.you were simply being asked to back up your claims with real world facts,not theorys.A person cant state a theory as a fact,they are two different things. The methods used to extract power from a normaly asperated(spell check) V8 engine is exactly the same as my 400ex. I was simply trying to explain a way for you to determine your precise compression ratio. But to heck with all that crap,you probably ride a hell of alot better than me,so what does it all matter?