dt200 piston question

It works by altering the height of the exhaust port and changing the power delivery the engine creates. When the engine is ran from idle to say max RPM. The CDI sends information to the powervalve control motor which inturn causes the powervalve servo motor to rotate. When the servo motor rotates, 2 cables connected to it raise(turn) the powervalve. So basically at idle the powervalve is nearly closed, as the RPMS increase it is opened up. It allows you to have all the benefits of a motor ported for top-end while still retaining bottom end power. The valve is a slightly ovular shape. This changes the height and size of the exhaust port at different engine speeds, maximizing the available power at all rev ranges.

The port design on the DT is older and worse in some ways than the YFS200 engine, but with some good well thought out engine design this can be changed.

Make sense? I'm kind of tired, and tried to explain it as clearly as possible.
I'm sure it wouldn't be too hard to design some sort of mechanical powervalve system much like KIPS or the pre RC valve CR's, or even the YZ's. Just would take some time, and lots of R+D.
 
Please show us some pics of this mechanical set-up! I am really interested as well!! I need all the help I can get. I may need one more DT cylinder, is there anyway you could ship one at a reasonable price from Costa Rica?
 
I dont have pictures, but it is easy to make. We use a gas cable that has like a box, where this cable is divided in two, so u use one for the carb and the other to open the valve, so as you acelerate, it opens the valve; and we use another cable (it can be from a bicycle) with a spring that close the valve when you decelerate.
 
LUISFER764 said:
I dont have pictures, but it is easy to make. We use a gas cable that has like a box, where this cable is divided in two, so u use one for the carb and the other to open the valve, so as you acelerate, it opens the valve; and we use another cable (it can be from a bicycle) with a spring that close the valve when you decelerate.
Click to expand...

uhh thats what you did?

thats not a solution to the problem...

you do realize the powervalve operation is based on the RPM right... not throttle position? so when you fully crack that throttle, your going to have the PV all the way open... yet it may still be in lower RPMs
 
Roostinshee said:
It works by altering the height of the exhaust port and changing the power delivery the engine creates. When the engine is ran from idle to say max RPM. The CDI sends information to the powervalve control motor which inturn causes the powervalve servo motor to rotate. When the servo motor rotates, 2 cables connected to it raise(turn) the powervalve. So basically at idle the powervalve is nearly closed, as the RPMS increase it is opened up. It allows you to have all the benefits of a motor ported for top-end while still retaining bottom end power. The valve is a slightly ovular shape. This changes the height and size of the exhaust port at different engine speeds, maximizing the available power at all rev ranges.

The port design on the DT is older and worse in some ways than the YFS200 engine, but with some good well thought out engine design this can be changed.

Make sense? I'm kind of tired, and tried to explain it as clearly as possible.
I'm sure it wouldn't be too hard to design some sort of mechanical powervalve system much like KIPS or the pre RC valve CR's, or even the YZ's. Just would take some time, and lots of R+D.
Click to expand...

I was going to say....it wouldn't be all that hard to rig up a strong RC Plane servo to a tachometer and throw it on there.....of course you would need a legit tach that would operate well.
 
That was an idea i had, saw a RZ350 with RC plane servos. Got any experience with RC planes or robotic wiring?
 
Also how about the self cleaning (simple man terms) compression lowering operation the powervalve performs everytime the ignition circuit is closed?
 

Thats a YPVS being controlled by an RC servo. Do we have any electrical gurus here, I could figure it out if need be and have some knowledge of complex electronics. I'm a mechanical engineer tho...

Here's another cool video, dude made his own adjustable ignition.


Just find this fascinating: the Capacitor discharge igntion is simple, but here it is in action: Homebrew style!:
 
Last edited by a moderator:
Roostinshee said:
That was an idea i had, saw a RZ350 with RC plane servos. Got any experience with RC planes or robotic wiring?
Click to expand...

Yea, I've built some RC Planes and am building one now. I don't know how fast or strong of a servo you would need for the powervalve. Servos can cost anywhere from $8 to $100+.....doubt you need one that high end. They typically have wires that hook up to little battery packs or alternate sources of power and are controlled by the receiver for the RC radio controller. That might be the hardest part in programming it to work in sync with a tach. That's why I was asking how the DT200 servo operated to get a better idea of how Yamaha set the system up and what kind of servo they used.

Here is how RC Planes have direct links to servos. The DT200 obviously has some indirect link somewhere that controls the servo.
 
Last edited by a moderator:
Roostinshee said:
YouTube - rc-ypvs-styrning.mp4

Thats a YPVS being controlled by an RC servo. Do we have any electrical gurus here, I could figure it out if need be and have some knowledge of complex electronics. I'm a mechanical engineer tho...

Here's another cool video, dude made his own adjustable ignition.

YouTube - w-spark removed.mp4

Just find this fascinating: the Capacitor discharge igntion is simple, but here it is in action: Homebrew style!:
YouTube - DIY CDI / Capacitor Discharge Ignition
Click to expand...

He looks like he is using a cheap servo just based on the speed of it. He has it mounted laying on it's side with the "head" of the servo contacted with the powervalve gear. If you get a servo, I recommend getting a durable one with metal hookups to withstand the offroad use and one that is faster than the one he is using simply because if you are revving quickly, you want a servo to respond quickly in accordance. My guess is he is just using a radio controller that you would use with an RC plane to illustrate how his setup works. I'd message him on youtube or whatnot and see what servo he is using, how he programmed it to work in sync with the variable RPMs of the engine, and all that jazz. I can't say much because I don't know what the "brains" are that controls the stock servo on the DT200. If you can find them or whatever controls it, then you can go from there and probably just plug and play a servo into it and you are on your way.
 
I have a good servo, but don't wanna risk taking it apart and messing it up. even though I know how, it's just murphys law. Anyways, I am going to see if someone will hook me up with a bad servo and lemme see the guts and design my own system based on your recommendations and the guys down from the oz. Thanks for the useful information, rep will be given shortly.
 
Hey all. I got sum DT parts. Top end, side cover, servo and a complete engine. Paid big bux to get them shipped from Canada over a year ago. Plans changed and need $$$
 
Hows it going boys I just scored a 95 Dr200r 3ET for 400 bucks from my buddys son, the plastics are rough but i could care less about that, the motor is in good shape, its never been rebuilt and all original, the topends toast and it needs new crank bearings. I have the bike stripped and I painted the frame and Im just waiting for the bearings to do the bottom end, Im praying the powervalve servo and cdi are good, I never even thought of testing them, I own a 240 stroked blaster as well
 
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Jess brown said:
Hows it going boys I just scored a 95 Dr200r 3ET for 400 bucks from my buddys son, the plastics are rough but i could care less about that, the motor is in good shape, its never been rebuilt and all original, the topends toast and it needs new crank bearings. I have the bike stripped and I painted the frame and Im just waiting for the bearings to do the bottom end, Im praying the powervalve servo and cdi are good, I never even thought of testing them, I own a 240 stroked blaster as well
Click to expand...
a DT not DR my bad
Jess brown said:
Hows it going boys I just scored a 95 Dr200r 3ET for 400 bucks from my buddys son, the plastics are rough but i could care less about that, the motor is in good shape, its never been rebuilt and all original, the topends toast and it needs new crank bearings. I have the bike stripped and I painted the frame and Im just wlbearings to do the bottom end, Im praying the powervalve servo and cdi are good, I never even thought of testing them, I own a 240 stroked blaster as well
Click to expand...

not dr lol
Jess brown said:
Hows it going boys I just scored a 95 Dr200r 3ET for 400 bucks from my buddys son, the plastics are rough but i could care less about that, the motor is in good shape, its never been rebuilt and all original, the topends toast and it needs new crank bearings. I have the bike stripped and I painted the frame and Im just waiting for the bearings to do the bottom end, Im praying the powervalve servo and cdi are good, I never even thought of testing them, I own a 240 stroked blaster as well
Click to expand...
skypilotj said:
Hey all. I got sum DT parts. Top end, side cover, servo and a complete engine. Paid big bux to get them shipped from Canada over a year ago. Plans changed and need $$$
Click to expand...
 
Jess brown said:
Hows it going boys I just scored a 95 Dr200r 3ET for 400 bucks from my buddys son, the plastics are rough but i could care less about that, the motor is in good shape, its never been rebuilt and all original, the topends toast and it needs new crank bearings. I have the bike stripped and I painted the frame and Im just waiting for the bearings to do the bottom end, Im praying the powervalve servo and cdi are good, I never even thought of testing them, I own a 240 stroked blaster as well
Click to expand...
Sounds like a fun project. Got any pics.
 
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