20 Most Recent 2003 Yamaha DT 125 R - Page 2 Questions & Answers

You've put indicator wires in the wrong way that's why...

2003 Yamaha DT... | Answered on Nov 14, 2012

The first thing to do is get a new stock spark plug. Hook up the plug wire then have someone kick the lever while you hold the metal side of the plug against the bare metal cylinder head looking for spark while the starter is being kicked. If no spark is seen, find out why. Use a meter to check the handlebar and side stand switches for proper operation. How good is the battery? Are there any wires abraded or disconnected? Has the pulse generator, coil or CDI gone bad?
If spark is present, Be sure the air cleaner is clean. A dirty filter restricts the air the carb needs. Okay, you have spark and you have air, now you need gas. Start by draining the carb. Condensation from the gas tank can get into the carb float bowl and build to the point the carb is feeding only water into the engine. Engines don't run well on water. When starting the bike, do not go nuts with the throttle. Every twist on the throttle sends a shot of gas into the engine. Too many twists can flood the engine. Your bike is water cooled. Good gaskets/seals are needed on the cylinder and head. At this point we will assume the coolant system is not leaking.

2003 Yamaha DT... | Answered on Jun 16, 2012

alright mate normally the 2 wires are + and the earth is connected to the frame

2003 Yamaha DT... | Answered on Jul 24, 2011

Assuming you are talking about the right side casing, you are correct. A center case leak is a whole different matter.

2003 Yamaha DT... | Answered on Mar 10, 2011

if you are turning to open up the valve for more power then you are making a mistake. power valves open the upper exhaust ports to allow the exhaust gas to exit faster being pulled by the exhaust pulses from the expansion chamber. by opening it and setting it in the fully open position would rob the engine of all its low down power making the bike useless below 5000 rpm which is where your power valve would start to open, it would also waste fuel as it would be sucked straight into the ex possible causing lean running conditions .

2003 Yamaha DT... | Answered on Apr 26, 2010

Your barrel? LOL. Sounds like the valves need to be gone through. I would suggest taking and valve train apart and put it back together correctly then go from there.

2003 Yamaha DT... | Answered on Apr 14, 2010

The bike is 19 years old. Caseings will be VERY hard to find. Suggestion; take the case to a welding shop and ask them to weld the crack. Teey will have a MIG or TIG welder which will do the job and the cost should only be about 20 bucks.

2003 Yamaha DT... | Answered on Dec 10, 2009

The service manual has a diagram, but you need to zoom in to read the colors.
You can download a free one at
Good luck!

2003 Yamaha DT... | Answered on Nov 21, 2009

could be that your woodruff key on your flywheel is sheared off and put the timing out a bit, this happened on my bike, or your air filter may be blocked, maybe the floats are stuck in the carb and flooding.

2003 Yamaha DT... | Answered on Nov 15, 2009

You have a poor or missing earth on your lights and are getting feedback. Earth with a spare piece of wire each lighting earth point to isolate. The bad earth will be shown when the fault stops by using the tempory earth wire. Remove faulty earths and clean contacts.

2003 Yamaha DT... | Answered on Oct 31, 2009

try squirting fuel in carb does it fire for a second if this happens

2003 Yamaha DT... | Answered on Oct 12, 2009

6th is a long legged gear. Never expect much from it.

2003 Yamaha DT... | Answered on Oct 04, 2009

your valves are too tight, adjust your valves and it will start fine..

2003 Yamaha DT... | Answered on Sep 10, 2009

The bike is restricted in qute a few places Ihave the same bike and have just de restricted mine im not sure what the other guy was meaning about the exhaust but he is right it is restricted if you remove the exhaust you will notice that there is a small pipe that has been welded in to restrict the amount of fumes that escapes this needs removing its held on with 3 welds i took mine ti a local car repar place they removed it for me for £20 . also check to see if your power valve servo is working mine wasnt so ive opend the case that has the pullys on it and put a screw in to hold the valve in mid way position ( i noticed a major diffrence in doing this ) also there is a small peice of rubber that you need to remove from the inlet manifold if you take the carb off and then the 4 bolds that hold the reeds in you will see a square bit of rubber cut this off to make it flush as this messes with the air fuel mixture . under the seat you will also find a snorkle just rip this off just yet another thing to mess with air intake . i have also drilled my air box but i wouldnt advise this if you use your bike in muddy areas unless you dont mind cleaning your carb all the time i would also get an irridum spark plug as it improves throttle responce

2003 Yamaha DT... | Answered on Sep 06, 2009

make sure the cable is not damaged and is it all adjusted properly try putting a bit off oil on it

2003 Yamaha DT... | Answered on Sep 02, 2009

adjust the shocker twist it

2003 Yamaha DT... | Answered on Aug 10, 2009

hi mate you dont need to change anything as im sure the carbs are all the same through the years also the only thing you need is a start switch

2003 Yamaha DT... | Answered on Aug 07, 2009

check the wiring, make sure that you are using the bulb with the correct rating. Also get the output in the headlight connector checked.

2003 Yamaha DT... | Answered on Aug 06, 2009

more details please.
1. if it starts can you rev it
2. how long does it run for
3.can you start it every time after it stops

2003 Yamaha DT... | Answered on Aug 02, 2009

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