When I change the oil

Have you checked the owners manual to see what can cause the bike to stop. It sound very much like the cut out switch to the side stand or clutch is faulty and is causing the engine to stop.

OK to check oil level you have a little dip stick on the left hand side on the frame of bike just in front of the fuel tank to check this dip stick you need to start the bike and idle only (not rev up or ride) and you idle the motor for 2-3 minutes with the bike in upright position. then turn off motor keep in up right position and remove dip stick - wipe the stick clean then insert dip stick back in its hole (without screwing in) then remove it to see oil levels.
a good quality 20w-40 weight oil (motor bike specific) is a good choice but pretty much any decent oil from your motorcycle shop would be OK just discuss it with them when you purchase it I not sure what country you from but where I live our Yamaha shops sell Yamalube and this is perfect a bit pricey but for our favourate toy, it is worth it!
To fill the oil there is another plug on left hand side again at the front end of the motor you will see it is the only plug there that can be opened with fingers - you will need a funnel to fill cleanly as is pretty difficult to pour into it with out spilling otherwise?
Your bike holds only 1.2 liters (1200ml) of oil in total so if you not changing oil filter and completely emptying then oil lines, only add up to 1 liter for a simple oil dump and refill.
Hint for the day with oil is - On a MX bike the more often you replace the oil the longer it will last before needing repair I would always recommend changing oil either once a month or every 3 hours of riding use which ever comes first !
I am often told I am over cautious with this oil change strategy but I also have YZ450f 05 and a 2003 model and I have never had to rebuild because of break down or fault with motor
Maybe this is coincidental ? but then again - Maybe not ??
good luck hope this helps a little
regards Jamie

there is drain nut beneath your engine it is big in size...........open it up and place a tub beneath it for the old oil to come out wait for 10 minutes and also open the poring point it is a plastic made and is also works as a leveler and then after getting empty put the nut situated below the engine back into its place and fill the oil till the recommended level and start the engine for 2 minutes at a normal speed

i would suggest using a good 10w 40 engine oil and simply put the bike on the centre stand pouring in 2 litres to start thats if the bike has been drained empty then just top up little at a time untill oil is in the markers on the dip stick the bike will hold around the 3 litre mark from empty hope this helps

Start the engine and warm to operating temp. and stop motor and place bike on a stand so it is level.
Drain oil into suitable container for disposal.
Let drain for 10 minutes.
Replace tank and frame drain plugs and refill with 1.2 litres of oil, 1.3 litres if changing filter. Capacity is 1.4 litres.
Oil filler cap is on the top left side front of the crankcase cover.
Run bike for a minute or so and let stand for 5 minutes. Take out dipstick (in front of left side of radiator shroud) and wipe clean. Place dipstick back in but do not turn in, take back out and read level. Adjust level as necessary.
The first site link below has diagrams in exploded view for your bike for assistance.
Alternatively, a free downloadable 35mb servicing manual is available, select motorcycle, type your model and year and download free.
Goodluck and cheers.
http://www.partforyamaha.com/pages/parts/viewbybrand/2/Yamaha.aspx
http://www.yamahaownershandbook.com.au/?r=0

Change and refill oil and change oil filter, refill coolant to it's level with proper mixture. Run bike on idle for 10-15 minutes, do a burst of revs and run constant rev at 5000 rpm for 20-30 secs, watch exhaust pipe smoke condition and if temperature gauge indicates overheating. Let bike cool off and check oil and coolant state. If you see milky oil, oily coolant and reservoir going empty, you may have a cracked cyl head walls. Happy hunting.

Dealer's usually tell you the amount you need if the bike is completely empty. Take a turkey baster and remove some oil, ride the bike and check the oil level again. I have seen to much oil blow the dip stick out and cover everything with oil and I have seen the oil tank split.

there should be a little window just below the oil fill area that says high and low, that's where you gauge the level of oil you have. it's not a dipstick, and not very precise, but that's it.

Hi,

The TM 125 uses 550 ml of gear oil. There is level inspection screw situated behind the rear brake lever. Access is a little tricky, but not too tough.
For racing motocross I recomend ATF, but must be changed after each race day.
For enduro, outriding or Sunday riders, BelRay -Trans Oil 80 W is best. You should change oil roughly every 500 km to prolong gearbox life.

Regards

Jon

Also check that bike is properly positioned. Is bike on level ground? With most bikes oil is checked on center stand or holding bike upright not on side stand. Also check manual some bikes say to check hot very few with cold motor. (many bikes with oil tanks will fill up crankcase and appear empty if checked cold especially after sitting for a long time) Most will say to wait a period of time after turning off motor (usually between 10 and 30 min.) but some say to check immediately after turning off. ,