20 Most Recent 2003 Yamaha DT 125 R - Page 8 Questions & Answers

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Yamaha DT 125 R... | Answered on Nov 08, 2010

Since you do not give any details we will just make this as generic as possible to try and help.
Check all panels and cover plates to make sure these are secure. (especially any loose screws)
Check the spark plug(s) to ensure these are tight.
Check cables to make sure all are secure especially near the engine.
(clips and holders come loose and sometimes rattle as they dance around to the engines tune)
Spark knock does not sound like a rattle. However you can try using a higher octane to see if things improve.
Check the battery and make sure it is secure.

Hope this helps.
About all I can think of right now.
Good luck!

Yamaha DT 125 R... | Answered on Oct 29, 2010

10w40 motor oil. NEVER use synthetics. They can mess up the clutch.

Yamaha DT 125 R... | Answered on Sep 12, 2010

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Yamaha DT 125 R... | Answered on Aug 31, 2010

what year, modle..need full discription.....have you checked the "clutch cable" may be broken either at handle bar -clutch lever or at clutch housing case...

Yamaha DT 125 R... | Answered on Aug 15, 2010

It is pretty easy. Remove the old points then install the new set. There is a slot where the lockdown screw goes. The slot limits the adjusting range yet allows the adjusting plate to move left and right to set the timing. The lockdown screw gets snugged up just enough to hold the points assembly in place so you can stick a screwdriver inside the flywheel and into the adjusting point to move the entire points assembly. Moving the sssembly makes the timing earlier or later. A dial gage is screwed into the spark plug hole to gage the position of the piston. The timing should be set such that the points open at 1.8mm BTC.. An ohlm meter will show you the moment the points break contact. You can check the timing with a timing light if your particular machine has an index mark on the flywheel and a static mark on the case. Not everyone has a dial gage, Ohlm meter and timing light. In general, set the points gap at .012 to .015 and you should be about right. The gap is set with the arm riding on the high point of the magneto center lobe. Please take a moment and rate my answer. Thanks.


Yamaha DT 125 R... | Answered on Aug 04, 2010

Neutral should be between 1st and 2nd. Likely cause could be worn or bent shift forks and/or shhift drum. Both are inside the transmission and will require engine removal and case splitting.

Another less likely, but easier repairable cause could be a damaged or miss aligned shift linkage inside right side cover of engine.

Yamaha DT 125 R... | Answered on Jun 12, 2010

A dealer run 11 to 15 hours at there labor rate .Plus all the parts necessary to complete the repair

Yamaha DT 125 R... | Answered on Jun 10, 2010

Check the wiring exiting the crankcase up to the rectifier/CDI unit and ignition coil. Look for excessive squashing, pinched or burnt (very stiff) wiring. Check all connections are firm and free of corrosion. Ensure plug lead is not arcing to frame or engine when in place. Make sure ingition coil is FIRMLY earthed at mounting point. A good tip is to run an earth wire from the head bolt to the frame. Thoroughly check any "kill switch" wiring as moving handlebars, throttle cable etc whilst kicking over may interupt electrical circuit. It is common for wiring to eventually get caught up in the steering "stops" on the lower fork clamps, cutting or severely damaging wiring. The wires exiting the crankcase come from the generator and without a rotor puller they will remain unsighted behind the generator rotor. You can easily remove the cover however, and check grommet where loom enters for pinched or flattened wires.
Check the site below (scroll down for your Model/Year) It has exploded view diagrams of all the pertinent parts to see your bike going again. Cheers.


Yamaha DT 125 R... | Answered on May 18, 2010

your battery helps the voltage regulator. you need a good battery, on old machines if one light goes out others will burn out also. make sure all of your bulbs are good. but make sure you have a good battery (6 Volts) that is hooked up and your main fuse is good.

Yamaha DT 125 R... | Answered on May 09, 2010

It is a simple job to rebuild a dt125r as it is 8 or maybe 9 bolts holding the head on, drain the coolant into a container so you con use again, undo the 5 bolts holding the cylinder head on(after taking the spark plug and coolant pipes off) after this undo the cylinder bolts should be 5 bolts to undo(12mm socket or spanner)t take the cylinder off the undo the gudgeon pin holding the piston on, at this point all you should see on the engine is the engine block with a con rod coming out of it. After you have the engine dismantled measure the bore diameter and then go to B&Q or any hardware store and get a circular sanding head for a drill that is maybe 5mm-10mm bigger than the bore, put the sander inside the bore on full power and hold it there for atleast 1minute and 30seconds, this should get rid of all of the score marks on the bore do the same to the piston(go round all score marks to make it smooth), get som gasket paper(or a engine set for dt 125r but gasket paper is only £1.09 from most shops) blue tak it to the top of the bore them go aroud it with a hammer very lightly so u have a gasket to fit the head on both ends, use a line of gasket glue(big line about 5mm in depth) all the way around the head and assemble the engine, this will only be temporary untill you have to do agen but it is cheaper than spending £150-£190 on new bore and piston.

Yamaha DT 125 R... | Answered on Mar 18, 2010


Yamaha DT 125 R... | Answered on Nov 03, 2009

yep sounds like it needs rings the dt50w usualy has lots of torque down low so if you are having ti rev the **** out of it somthing is not right only other option would be that the previous owner messed with the sprokets to get more speed but lost low end torque
good luck

Yamaha DT 125 R... | Answered on Oct 17, 2009

Use graduated measuring bowls and remember RELAESE pressure first before doing thisl...then crack open the drain scews and messure amount..this will ball park it. use 10 weight oil to replace. dont put more that a couple pounds of air backin the shocks they dont need nuch more then 4-6 psi. if you us ea gas station to inflate only squirk for as second then measure you might blow the seals..remeber very little air.

Yamaha DT 125 R... | Answered on Sep 14, 2009

it may have a dirty carb remove the float bowl and clean out the **** that may be inside, it may be as easy as that reassemble float bowl and start, if problem is not fixed remove the carb disassemble and clean then reassemble and try again to run the bike, remove the fuel hose from tank and ensure that a good flow of fuel is coming through fuel delivery hose from tank.

Yamaha DT 125 R... | Answered on Sep 06, 2009

u made my day by goin oldschool-sounds like the floats r stickin or bent-if u buy a clymer manual theyll show in detail disassembly n specs-walnecks classic mag would be worth a google

Yamaha DT 125 R... | Answered on Sep 05, 2009

i have the same problem. i have recently bought a 1998 dtr, but when we had a closer look at the engin, it wasnt worth keeping. so managed to get a 2006 engin. i fitted this. but the bike seems reallys slow. I then opend the powervalve. but the bike boggs out just as i get in to the power band. i was told to re jett the bike to a 260. so will be getting that done soon. will tell you what it goes like mate.

Yamaha DT 125 R... | Answered on Sep 05, 2009

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