Yamaha DT 125 DERESTRICTING
-
You need to remove the pulley/cables from the end of the power valve, then rotate it anti-clockwise about a third of a turn (until you can see as much piston as possible) then replace the pulley/cables.
Check the the pulley moves clockwise, then back, when you turn the ignition key. If it moves anti-clockwise you have the cables back to front...
Please do this... -
@SpookDog I think it's the angle of the pics that's making the valve look more closed than it is. As if you look at the edge of the powervalve nearest the exhaust it looks close to level with the surface of the exhaust port.
-
@Lukas55 Lukas55 the piston shouldn't hit the valve what ever position it's in. The piston normally won't normally touch the valve unless your barrel has been re bored 57mm or more. And then you need to grind the valve down to create clearance.
In that pic you've just posted the plastic pulley is how it's supposed to be with the valve completely open. If you look up the exhuast port it should be more or less level all the way to the piston. If it is like that with the pulley in that position that parts set correct.
Then it's a case of making sure the valves in the correct position for what ever revs the engines doing. -
@Lukas55 Lukas55 the piston shouldn't hit the valve what ever position it's in. The piston normally won't normally touch the valve unless your barrel has been re bored 57mm or more. And then you need to grind the valve down to create clearance.
In that pic you've just posted the plastic pulley is how it's supposed to be with the valve completely open. If you look up the exhuast port it should be more or less level all the way to the piston. If it is like that with the pulley in that position that parts set correct.
Then it's a case of making sure the valves in the correct position for what ever revs the engines doing. -
I was looking at the utube clip, not a pic. You can see the vertical seam where the 2 halves of the power valve fit together. It’s almost 2/3 to 3/4 closed!
Yes, move the power valve that way! (anti-clockwise) The pulley should fit snug back onto the diamond of the power valve after without adjusting the cables too much. You should be able to run your finger from the piston to the exhaust port outer edge without feeling any lips or hard edges. It should be smooth...
-
I was looking at the utube clip, not a pic. You can see the vertical seam where the 2 halves of the power valve fit together. It’s almost 2/3 to 3/4 closed!
Yes, move the power valve that way! (anti-clockwise) The pulley should fit snug back onto the diamond of the power valve after without adjusting the cables too much. You should be able to run your finger from the piston to the exhaust port outer edge without feeling any lips or hard edges. It should be smooth...
-
If it’s open it won’t touch the piston! Open means the valve isn’t blocking your view of the piston.
Show me a pic of what you mean by ‘open’ please...I fear we might be losing something in translation..
-
Yeah, the valve is clearly not flush with the exhaust port.
It should be flush with the exhaust port when done.
-
Please turn it anti-clockwise till you can see the most of the piston without it being occluded by the power valve. I don’t know how else to say it...
-
@Lukas55 Took ages to find this post, thank God for the Search function.
https://www.youtube.com/watch?v=9eopT_gyAo4
I had the engine out my DT today, so under an inspection lamp I've taken the courtesy of creating a very short sweet video of the powervalve in its fully open, to fully closed back to fully open state.
Yours should match that operation.
-
@SpookDog This is how it looks. https://i.postimg.cc/Dmm09szC/IMG-20201003-140839.jpg
Can not really see how much it is on picture... -
