Early DTR's are easier to de-restrict than later ones. The early ones are restricted mainly in two areas:

	The exhaust on '89 to '98 models have a small piece of pipe welded into the flange end, which can be removed by using a DREMEL to cut the three welding seems.
This is the restrictor piece removed.

Making the YPVS work properly

(Before you start, remove the front pipe so that you can see/feel when the power valve is adjusted correctly.)

To help restrict the power on the UK version, the manufacturers have also fitted the Power Valve round 180 degrees from where it should be for the Full-Power model.

 

To make the YPVS work properly, do the following:

1.  Remove screws 1 and 2 and remove the pulley cover. Or just remove screw 2 and turn the cover to one side.

Before you continue, make a note of the position of the pulley. (As it needs to go back on in exactly the same position).

2.  Next, loosen the adjuster nuts 3 and 4.

3.  Then wind the adjusters 5 and 6 in far enough so that the pulley cables have plenty of free-play on them.

4.  Now remove the bolt (7) that holds the pulley in place.

5.  Unhook the pulley cables from the pulley and put it to one side.

6.  Now you can see the end of the Power Valve: Turn it round 180 degrees (half a turn).

7.  Now the Power Valve is round the correct way, you can put it back together.

8.  Get the pulley and re-attach the pulley cables in the same place. Now push the pulley back on to the end of the Power Valve, and ensure that point number 9 is in the same position as it was before you removed it.

9.  Now refit bolt number 7 to the center of the pulley.

10.  Unscrew adjusters 5 and 6 until most of the slack in the cables have gone.

11.  To get the pulley in exactly the same position as it was before removal, tighten one cable adjuster by half a turn, then loosen the other cable adjuster by half a turn. Keep doing this until the pulley it is where it should be.

12.  The cables should have a small amount of free play (1-2mm movement on the pulley) otherwise it will stop the servo from turning properly. Tighten the adjuster nuts 3 and 4.

13.  Turn ON the ignition and you should hear the servo turning freely, if it sounds slower than normal at turning then the cables are too tight. When you think it is set right, refit the pulley housing and replace screws 1 and 2.

14.  Your YPVS is now sorted!

When you've done the other de-restrictions below, you should hear the exhaust note get louder and deeper as the revs go past 7200rpm. This sounds a whole lot better if you replace the standard silencer with a DEP SPORT silencer.

	There were some '97-'99 model DTR's which had an extra box in the wiring, situated at the bottom of the two stroke oil tank with four wires going into it. If you've got this box on your bike then you'll need to remove the side panels, seat and fuel tank so that you can gain access to the wires talked about below.
The following two pictures below show you where the wires from the extra grey box are connected to the wiring loom. The wire colours are red, yellow, blue and green:
The wires are originally connected as follows: The red wire is connected to a brown wire from the regulator. The yellow wire is connected to a red/white wire which goes to the CDI magneto under the left hand engine casing. The blue wire is connected to a yellow wire on the bike's wiring loom (i'm unsure where this wire goes to). The green wire is connected to the red/white wire coming from the CDI. These wire connections now need to be re-arranged as explained below: Disconnect the red wire and neatly tape the end of the wire up (this wire is not used anymore). Do the same for the blue wire (this wire is not used anymore either). Join the green and yellow wires together and wrap the joint with insulation tape. Join both of the red/white wires together and wrap the joint with insulation tape. Now the grey box has been re-wired, neatly tuck the wires back up into the loom and refit the fuel tank, seat and panels. Don't forget to reconnect the fuel pipe to the tank, (this can easily be forgotten to do!)