Yamaha DT 125 DERESTRICTING
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@SpookDog That's how I usually set my valve.
I've never encountered problems aligning the valve.
Going from a completely broken setup to work.
Turn ignition on and off. This is how the powervalve should be when it is fully open.
So it is just a case of adjusting the cables so that the valve is flush with the exhaust port. In some instances people have put the cables around the wrong way so that it is not operating correctly. But that's easily rectified.
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Yeah, the cables are clearly numbered 1 & 2. In my case they didn’t match up. I had to cut some outer off of one as well, to make it fit and work.
unbelievable!Getting the power valve fitted and the servo working was like one of the biggest mine-fields since the Somme
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Does my DT sound properly?
https://youtu.be/Id1jsvah8T8 -
I sounds like a dog!
Seriously though, it sounds a bit ‘clicky’ to my ear. A bit hesitant as well maybe...
It’s really hard to tell without being there and hearing the whole range of sound frequencies...P.S. Have you done your power valve yet?...
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Any old 2litre bottle top will plug the hole...
I didn’t want to say before but does that piston look like it was partially heat seized? Those are vertical score marks, no?
Not that I haven’t run a lot worse before 🤪
Sort out the power valve and see how it runs after bud. Then worry about if the top ends rattling. It could even be too much back pressure from an over closed power valve making the piston slap??P.S. is that the side bottle, or the one that sits on top of the inlet manifold?...
My eyes aren’t as good as they once were... -
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It’s over 57mm I think that it needs reprofiling ...
Make sure the power valve isn’t 180 degrees out. As long as it is fully open when the engine is off it’s ok. That and the cables are right. You should notice a huge increase in performance. Let us know how you get on...
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Best way of checking the valve is open when it should be, is to rev the bike over 7k. Then turn the ignition off (while it's above 7k). Then check the position of the valve. From what I've heard on here, different years operate the cleaning cycle etc of the valve differently.
If it's revving out fine in fifth. It might just be down to a not 100% healthy engine not having the power to pull 6th gear well. -
So when it is closed (when the bike is off) it looks like this...
https://www.youtube.com/watch?v=kephUMfdNIo&ab_channel=oupzySo the sound comes on higher RPMs when the valve is open I guess... Can I adjust it with cables on the side of the cylinder so there is less chance of hitting the piston or it is only possible with the cylinder off?
BTW sorry for my bad English... -
@Lukas55 removing the exhaust is the best way to check it 100%. You could always mark the power valve pulley and housing, with some paint or similar, while you have the exhaust off and the valves in the fully open position. That'll save you having to keep removing the exhaust to check. Just make sure you turn the engine off with the key switch once it's revved above 7k rpm.
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It is not supposed to be closed down like that. It is supposed to be as open as it can be. It only closes (less than that as well!!) when it does a cleaning cycle when you turn the key, and when the engine is running at low revs...
You can see the pulley move clockwise to close the valve when it cycles ant then when you run the engine at lower revs ...
Again OPEN when the engine is not running...
