Under power

shaunp1912

Got myself a 1990 dt125r starts first kick and runs through the gears great but flat out struggling to hit 60 mph
Just serviced by me new air filter oil new full exhaust
Revs fine up to 9500 but just doesn’t feel right, last one I had hit 75 plus no issues
Any ideas

Randall

@shaunp1912 check behind the clocks for a reed valve switch little green thing In a glass tube tape it up put some vas on it to stop it getting damp should re-restrict it depending if it's the dtr pre 2003 if it's the re2004 model then it's electrical to de restrict

Calum

Sounds like powervalve to me.

shaunp1912

@Calum
I have just removed the power valve cover the power valve does not move when I rev the cables are attached, what could be the issue

Calum

@shaunp1912 Don't worry about that for now.

Just make sure the valve is completely open, then disconnect the servo. Then take the bike for a spin.

It'll be down on bottom end, but should pull hard to the red line. If it doesn't then it'll be something else.

shaunp1912

Is the power valve controlled electricly ?
As my battery is flat and won’t hold a charge,

Calum

@shaunp1912 The DTR's, unlike the E, don't generate enough power to operate the electrical components properly. A flat battery, even on an E, causes issues with the valve.

So that sounds like your problem.