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Anybody done much port fettling?
Posted: 04:18 pm Mar 16 2011
by moto_psycho
khl
Posted: 04:39 pm Mar 16 2011
by Julien D
Boost bottle, maybe worth it, maybe not. I've heard it both ways. Doesn't seem enough to be worth the trouble. If it adds power anywhere, it will be low-mid, so that is what your friends DT125 exhibited.
As for porting. Take it to an expert. You don't know what you're doing. Waste of time.
hehehe. Sorry, could not resist. I have nothing helpful for you there, but I am certainly interested to see if you get any good results. Without a method for flow testing the cylinder, it seems kind of pointless to me to start hacking on the ports. If you are brave enough to have a go at it though, I look forward to seeing what you come up with. Be sure and take pics!
Posted: 04:47 pm Mar 16 2011
by Mr. Wibbens
Last thing I'd ever want to do with my KDX is port it
Heard about too many people over the years that sent their stuff to "so called" pros and specified "port for pump gas" but ended up having to run race gas
Posted: 05:26 pm Mar 16 2011
by moto_psycho
As I said, I am interesting in just improving the flow, not actually changing the porting, I am talking about fixing the defects that are left behind by the rough casting methods that actually keep bikes cheap!
Though I will be milling the head so the piston has the right squish band clearance for the piston/conrod/crankshaft accumulative tolerance error :D!
I'm definitely going to do it as a lot of it is common sense, just matching the cylinder to the crankcase and gasket, smoothing out the ports (this is not a 4-stroke so a porous port is not required for atomization!), smoothing the points between the 2 ports, adding a slight radius to ports in the cylinder (stock they come too sharp, not good for flow or piston rings).
Putting it plainly, I'm not trying to improve on kawasaki's design, just polish it a bit (as they can't really employ people to attack every engine with a die grinder to perfection).
Posted: 05:44 pm Mar 16 2011
by scheckaet
moto_psycho wrote:I'm definitely going to do it as a lot of it is common sense, smoothing out the ports (this is not a 4-stroke so a porous port is not required for atomization!)
Do you have data to show? Why the hell wouldn't it need to be atomized?
Posted: 05:51 pm Mar 16 2011
by Julien D
Gonna have to concur with scheckaet. I've always understood that the rough casting helps matters. If smoothing it out makes any difference, I don't know if it would be for better or for worse. Either way I doubt it will be enough to notice. Like I said, without some way of flow testing the cylinder how will you know? Butt dyno? Not always reliable. It's pretty easy to trick yourself into thinking it's running better.
Posted: 05:55 pm Mar 16 2011
by Tedh98
My understanding is that you want a rough intake port to aid atomization and a smooth exhaust to promote flow and help reduce carbon buildup.
Rough doesn't mean casting flaws and such, but rather you don't want a mirror smooth surface.
I could see port matching being worthwhile, but not much more beyond that.
Posted: 06:01 pm Mar 16 2011
by Julien D
Tedh98 wrote:My understanding is that you want a rough intake port to aid atomization and a smooth exhaust to promote flow and help reduce carbon buildup.
Rough doesn't mean casting flaws and such, but rather you don't want a mirror smooth surface.
I could see port matching being worthwhile, but not much more beyond that.
I like this post.
Posted: 06:08 pm Mar 16 2011
by moto_psycho
Tedh98 wrote:My understanding is that you want a rough intake port to aid atomization and a smooth exhaust to promote flow and help reduce carbon buildup.
Rough doesn't mean casting flaws and such, but rather you don't want a mirror smooth surface.
I could see port matching being worthwhile, but not much more beyond that.
on a 4-stroke that is correct as it goes straight from carb, through the valve to the combustion chamber.
2-strokes are completely different as they travel through the read block, through the crankcase, through transfer ports, into the combustion chamber, out the exhaust, then back in the combustion chamber. atomization has and will never be a problem on 2-strokes, it is all about flow.
hence why all 2-stroke tuners provide a "port & polish" service
once again, i started a thread asking for decent 1st hand knowledge and experience and have found myself having to explain the reason why i and everybody that has ever tuned a 2-stroke has done it!!!! i know what i'm on about and am looking for members of the kdx community that have tried it too!! if you have never done this mods for yourself please do not reply, its incredibly frustrating and time consuming having to explain.
and if you haven't any experience then at the very least please read this book before offering your "expert" opinion, either that or link me to the book you've written
http://www.kreidler.nl/artikelen/perfor ... m-bell.pdf
Posted: 06:48 pm Mar 16 2011
by Mr. Wibbens
If you are such an expert why even bother bringing it up??
Posted: 08:00 pm Mar 16 2011
by gregp
OK. I have done it. On several motors, one being an H series KDX. To be 100% truthful, it would be a reach to say that it made a definate seat-of-the-pants improvement. It made me feel good, though, and it certainly did not hurt anything, power-wise. I usually clean up the transfer port vanes (at the base of the cylinder), as they are usually a bit rough and sometimes have some sharp edges. I have heard from reputable tuners that these vanes should not be "sharpened" but rounded nice and smoothly.
I also clean up any obvious imperfections that I find.
So, I recommend that you go for it. As long as you do not do anything drastic, the motor will run just fine, and you will feel good inside!
While you are at it, I presume that you will disassemble and clean the entire power valve system, and this is always a good thing to do.
Fredette offers a porting service, just for our bikes, but I am unfamiliar with what is entailed in this process. It is reputed to be a good mod, though.
Posted: 11:10 pm Mar 16 2011
by scheckaet
"i know what i'm on about and am looking for members of the kdx community that have tried it too!! if you have never done this mods for yourself please do not reply"
I come on this site to help, share and LEARN from the same kdx community.
You don't have to jump on your high horse when someone asks a genuine question.
I've been here quite a while and haven't seen many polish their cylinder. Usually when a topic doesn't show up often there's a reason, i.e it either doesn't work or the gains are hardly worth the effort, that's why I ask for an explanation about the atomization since nobody really gave a good one for it.
"its incredibly frustrating and time consuming having to explain"
took you about 2 lines to explain...that's all that was needed.
if you haven't any experience then at the very least please read this book before offering your "expert" opinion
I don't think anybody gave their "expert" opinion but simply tried to share some of their knowledge...
Where is Carv when you need him
Posted: 12:57 am Mar 17 2011
by Mr. Wibbens
scheckaet wrote:
Where is Carv when you need him
Reading ride reports at ADV
Posted: 01:21 am Mar 17 2011
by moto_psycho
gregp wrote:OK. I have done it. On several motors, one being an H series KDX. To be 100% truthful, it would be a reach to say that it made a definate seat-of-the-pants improvement. It made me feel good, though, and it certainly did not hurt anything, power-wise. I usually clean up the transfer port vanes (at the base of the cylinder), as they are usually a bit rough and sometimes have some sharp edges. I have heard from reputable tuners that these vanes should not be "sharpened" but rounded nice and smoothly.
I also clean up any obvious imperfections that I find.
So, I recommend that you go for it. As long as you do not do anything drastic, the motor will run just fine, and you will feel good inside!
While you are at it, I presume that you will disassemble and clean the entire power valve system, and this is always a good thing to do.
Fredette offers a porting service, just for our bikes, but I am unfamiliar with what is entailed in this process. It is reputed to be a good mod, though.
ohhh god thank you!!!!!!!!!!!
and to the rest of you, god knows why it doesn't come up in this community, perhaps because KDX's aren't at the peak of any race series, but if you look on forums for RD/RZ's or RG/RGV's or KH's and GT's THERE IS LOTS OF INFO
Posted: 01:46 am Mar 17 2011
by Mr. Wibbens
Posted: 06:21 am Mar 17 2011
by Julien D
lol.
So the dude you're thanking says take your time, do it right, and you won't be able to tell a difference in how the bike runs but you'll feel good inside? That gets an "Oooohhhh god thank you!!!"
And those of us who said don't waste your time get a big fffuu?
Nice. How about, don't waste your f'n time? Pretend you did it, then you can still have the good feeling inside without the wasted effort ;).
Posted: 07:00 am Mar 17 2011
by Tedh98
juliend wrote:lol.
So the dude you're thanking says take your time, do it right, and you won't be able to tell a difference in how the bike runs but you'll feel good inside? That gets an "Oooohhhh god thank you!!!"
And those of us who said don't waste your time get a big fffuu?
Nice. How about, don't waste your f'n time? Pretend you did it, then you can still have the good feeling inside without the wasted effort ;).
My turn - I like this post.
Posted: 07:41 am Mar 17 2011
by KarlP
Geeeeze, guys, lighten up on Psycho. He isn't going to hurt anything.
Hopefully he'll do some polishing and come back and say "I did this and the results was......"
Posted: 07:44 am Mar 17 2011
by rbates9
He might be on to something, most of the post I have read were saying more about it causing issues but maybe those port jobs just went to far?
Posted: 09:37 am Mar 17 2011
by fuzzy
My understanding is that you want a rough intake port to aid atomization and a smooth exhaust to promote flow and help reduce carbon buildup.
Rough doesn't mean casting flaws and such, but rather you don't want a mirror smooth surface.
I could see port matching being worthwhile, but not much more beyond that.
+2. Do not mirror polish your intake ports unless you like lots of spoo. I would match, and that's it....Unless you want to actually change the power characteristics. The most gain is in the head (lathe).
