Tuning for the Yamaha DT 125 R is popular, of course. Here in Germany teenagers of 16 years are allowed to drive the bike with limited power. So the bike may not drive faster than 80 km/h.
But with the age of 18 you can enjoy the full range of its engine performance. Here you can get tips how to increase the power of the DT. The YPVS (Yamaha Power Valve System) regulates the exhaust system.
With less modification you can get many "old-fashioned" limited DT 125 to its regular power. See more below!
On the left side of the cylinder you can find a round metal-cover, which is fixed with two screws. You can see some linkages get in there. Get the two screws and the cover off. Now you see a small black nearly round plastic part, which is fixed by a screw. The linkages are holded by this plastic part.
Pull in the linkage screws and hang it off, so you have more space to work. Now you release the screw and the plastic part. Under the plastic part you see a metall nose. This metall is one side of the valve. You can rotate that nose for 180°.
This is a good starting for finetuning. Now you install everything and have a test ride. With the linkages you can tune the valve exactly.
A few more words: You can see the valve when you disassemble the exhaust manyfolder. The corner of the valve should appear about 3mm from the upper side of the cylinder when it's in neutral position (see picture).
You can reach the valve's neutral position when you turn on ignition and wait for the valve turning through and back again. After that the valve persists in neutral position. See also the pictures!
After the year 1999 the bikes where provided with a cdi that limits power. There are faqs and docs that describe how to avoid the cdi's limiting. Have a look in the links and forum! Another option is to buy a tuning cdi. Even more power ;)
Although the cdi limits power, this limitation version should be prefered. Its advantage is that the engine's performance is at normal stage. Only when you reach the speed the cdi will stop the ignition. You see there are no disadvantages for example when you drive through town.
Also there are many shops that offer tuning part. For example you can get carburators and tuning exhaust manifolds / silencers. Have a look in the links-section for information, too!
There are many parts for "optic" tuning available. You can get other handprotector, headlamps, handlebars, seats, blinkers, etc.
You can easily change the sound of the DT. Another easy and cheap way, instead of buying an exhaust / silencer, you can do the following modification. Under the seat you find the airfilter-box and the air intake.
There ist a gum intake canal. When you detach it the engine sounds much more deeper because of the other intake sound. As any modification to the exhaust / intake system the resulting sound is individual preference but combination with another exhaust / silencer it even may be necessary to detach it. See also the picture below.
Also there are many parts for the bike, that can be used to tune the bike's appearing. As I said before you can get many lamp masks or other handprotectors. Often the small modifications will give a extra plus - e.g. an individualized chain-fender.
|When tuning the DT with exhaust / silencer it may be necessary to change the carburator's main nozzle. First open
the drain plug to empty the carburator. Hold under an bottle etc. so the fuel won't flow to the ground. For changing the main nozzle
release the bracket screws of the carburator muffs on both side - airfilter-box and fuel
intake. Now you can rotate the carburator a bit so you can reach the float gage cap. Release
the screws and detach the cap. Be careful that you don't cause any damage to the sealing.
Those small seals are expensive.
At this point you can see the copper coloured main nozzle covered by a white plastic part. You can pull off the plastic to reach the nozzle. Release it and change it through another one. Also here see the picture for some hints!
For more information please see th links!
Please note: When increasing a bike's power it may harm current laws. In some cases you drive without driving license or even without assurance!