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Post Info TOPIC: Reed Switch confusion

DTR Respected Member

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Posts: 70
Reed Switch confusion

Hi All 

as you may or may not know on the back of the dt's late 1999 to 2003 the is a reed switch wired into the back of the clocks, the wiring diagram shows this is wired into the CDI to the Power Valve. most people recommend or say this is a restriction and to pull it out the clocks and tuck it away behind the headlight.

|There seems to be much confusion on the internet as to what this actually does.

There seems to be 3 theories  

1. when the speed passes 60mph it activates the switch retarding the ignition to stop the revs increasing.

2. when the speedo passes 60mph it partially closes off the power valve attaining the same results as the first theory 

3. when the speedo passes 60mph it changes the CDI ignition mapping to advance the spark (this wouldn't be classed as a restriction)

i have tested these theories with a go pro recording the Powervalve cover on the side of the barrel 

instead of the reed switch i have replace this with a manual toggle switch so i can turn it on and off at will when going down the road,

my findings would conclude all 3 theories are incorrect.

i have passed 60mph and toggled on the switch for each test, the powervalve has no extra movement or adjustment nor do my revs decrease i can still rev to the redline and pull 70-75mph on GPS 

so is the reed switch just a myth or is it a unused feature on my current CDI 3rmj-20 ? 

any additional Info or ideas are appreciated if i've done something wrong please tell me !! 



2000 DTR 125

2010 Hongdou Urban DZ 125

1998 Derbi Senda r50

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