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Author Topic: High Velocity Porting  (Read 1874 times)

Offline Dirk1616

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High Velocity Porting
« on: January 10, 2017, 10:10:26 AM »
I've looked into doing some porting and the HVP (High Velocity Porting) has caught some of my attention, you know, adding epoxy and shaping the port. There is a long and in depth post on a YFZ forum for doing such and there is postings on Motoman's website about HVP that is teaches you everything there is to know about it. I'm just wondering if anyone has done it to a DS or if it's worth it? What people's opinions are of it? Stuff like that, now I know a lot of you will say, just go to a bigger carb, bigger cams, stuff like that. I'm just wondering what you all think about it. I've read OMR's post on porting. But do you all think doing a HVP job would be worth looking into or doing?
2003 DS Baja         Riding at Bundy Hill and Silver Lake
Big Gun CDI, 11.5 JE Piston, Port/Polish, OMR Carb Mods,
Custom Mod End Cap, UNI Filter, More To Come?

Offline persom55

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Re: High Velocity Porting
« Reply #1 on: January 10, 2017, 10:16:52 AM »
It's something I've always wanted to try but never had the time

Offline Dirk1616

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Re: High Velocity Porting
« Reply #2 on: January 10, 2017, 10:57:17 AM »
I know there are people here that would love to know what it can do. I am thinking about trying it out, but I'd like to have some insight if anyone has any.
2003 DS Baja         Riding at Bundy Hill and Silver Lake
Big Gun CDI, 11.5 JE Piston, Port/Polish, OMR Carb Mods,
Custom Mod End Cap, UNI Filter, More To Come?

Offline Dirk1616

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Re: High Velocity Porting
« Reply #3 on: January 11, 2017, 07:50:45 AM »
I was just poking around looking at DS photos on the web, seeing what people have done to them. But what I found was a picture of a DS Port with the High Velocity Porting!

http://i192.photobucket.com/albums/z183/erbe03/DS650/1450690_770770692951803_1697621322_n_zpsa3d9c834.jpg

I see the guy who put this up has a profile on here, but hasn't been on in a year (to date), I'd really like to ask him how he went about it and if he could tell a difference! Anything would be helpful. Is there anyone who could point me in the right direction?
2003 DS Baja         Riding at Bundy Hill and Silver Lake
Big Gun CDI, 11.5 JE Piston, Port/Polish, OMR Carb Mods,
Custom Mod End Cap, UNI Filter, More To Come?

Offline BigRay800

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Re: High Velocity Porting
« Reply #4 on: January 11, 2017, 01:59:43 PM »
just clean up all the rough casting marts to make it smooth, nothing fancy. People did all kinds of goofy things with that head back in the day, You can do more harm than good  if you just start hogging out material. so just clean up the intake  smooth down the rough stuff and do the same with the head and try to match the intake with the head
Ds650 powered by Suzuki GSXR 1000 [sold]
Girl made me buy a damn RZR

Offline persom55

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Re: High Velocity Porting
« Reply #5 on: January 11, 2017, 08:38:47 PM »
I was just poking around looking at DS photos on the web, seeing what people have done to them. But what I found was a picture of a DS Port with the High Velocity Porting!


That doesn't look like the high velocity porting that motoman teaches about.
The basic principle of HV Porting as I remember it was to make the port 30%smaller and leave it rough so that fuel can't bead up on it like a rain drop on a windshield


I would get me a dremmel with a snake attachment and some ball cutters I think and have a go. Probably on a junk-ish cylinder head though

Offline Dirk1616

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Re: High Velocity Porting
« Reply #6 on: January 11, 2017, 08:50:37 PM »
The High Velocity Porting is flattening/raising the floor of the intake and making a gentler curve going down to the valve. Also making the throat of the intake slightly smaller to increase the velocity. If done correctly, it shouldn't reduce flow that much, and should help keep air in the cylinder as the piston starts the combustion stroke when the valve start closing, the increase in velocity should help keep air inside.
2003 DS Baja         Riding at Bundy Hill and Silver Lake
Big Gun CDI, 11.5 JE Piston, Port/Polish, OMR Carb Mods,
Custom Mod End Cap, UNI Filter, More To Come?

Offline hsr-tm45s

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Re: High Velocity Porting
« Reply #7 on: January 11, 2017, 09:21:10 PM »
 At what rpm do you plan to run at.
made by Can-Am, shaken by OMW

Offline Dirk1616

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Re: High Velocity Porting
« Reply #8 on: January 11, 2017, 09:30:21 PM »
All range of rpms, most of the time it's mid to high rpms that I like to stay in. I ride in dunes, trails, hills, all sorts of terrain.
2003 DS Baja         Riding at Bundy Hill and Silver Lake
Big Gun CDI, 11.5 JE Piston, Port/Polish, OMR Carb Mods,
Custom Mod End Cap, UNI Filter, More To Come?

Offline hsr-tm45s

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Re: High Velocity Porting
« Reply #9 on: January 11, 2017, 09:40:10 PM »
Then I would say match the intake to the head, you will make power for the way you ride.
made by Can-Am, shaken by OMW

Offline Dirk1616

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Re: High Velocity Porting
« Reply #10 on: January 12, 2017, 05:26:14 AM »
From reading around, I've found that making the throat of the intake, 1cm above the valve seat, about 85% smaller than the valve is a good trade off between low rpm power and high rpm power.
I think I'll try it with the head I have now, I have another head I can swap onto it if this turns out to be a joke. My buddies 650 has the same set up I do, just not the HVP, so I can compare mine to his and see what kind of results I am getting. It won't be for another week or so before I get to it, little busy right now.
2003 DS Baja         Riding at Bundy Hill and Silver Lake
Big Gun CDI, 11.5 JE Piston, Port/Polish, OMR Carb Mods,
Custom Mod End Cap, UNI Filter, More To Come?

Offline Oldmanracing

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Re: High Velocity Porting
« Reply #11 on: January 12, 2017, 08:33:12 AM »
The size of the DS head is not the main issue.  If you cc the head and do the air speed calculation, the head is a 65hp head.
The main issue with the ds head is its approach angle.  As the posted DS picture shows, the floor has been filled, and the roof raised.  Volume did not change but the approach angle was greatly improved.
It is hard to maintain high inertia, if the angle near the valve is too aggressive.
If you only fill the floor, you gain bottom torque, but loose top because the head will become choked.
hsr-tm45s has the nicest intake manifolds to maintain inertia.  But his are for 2 carbs.
No one ever made a longer intake for a single carb application.
The old theory that fuel atomizes better if the carb is closest to the intake value.  Look at the intake manifolds on Pro Stock engines.
Now you can understand why the 725/730 big bore kits became so popular.  They increased the velocity for bottom and top.
Inertia can be controlled by port volume or port length. This includes the intake manifold and how you also control air pressure in the airbox. Maintaining pressure to control air tumbling is vital to both torque and hp.  Does't matter what the velocity is near the valve if the air is tumbling.  Everthing has to be in balance.

Offline ERBE

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Re: High Velocity Porting
« Reply #12 on: November 26, 2017, 08:48:53 PM »
LOL that photo was me asking about who did that head, had the same questions on some forum way back when



 

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