Question about 2003 Yamaha YZ 125

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I was riding my 2003 yz125 and it stalled since then i have not been able to kick start the bike i checked the plug and its getting plenty of spark i put a compression tester on it and its reading 150 psi so its not a compression problem i can push start it and it will run fine as long as you are on it but if not it will just stall out what could the problem be?

Posted by David Reynolds on


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  • 1 Answer

SOURCE: yamaha yz125 wont start...

hello there guys, listen a top tip is when the engine's cold tip the bike almost right on its side nearly touching the floof, wait for the petrol to poor out of the carb over flow pipe, this should take a matter of a few seconds, stand the bike back up again and kick and that baby should start right up, if it does then you have a problem with your float, if it still doesn,t then take it to a shop and get them to check it out, hope this helps. regards sam

Posted on Jan 24, 2009



  • 3567 Answers

SOURCE: VERY hard starting takes way to many kicks usually play out befo

There is a proper way to start the engine. Four controls are on your bike to assist in starting.

  • The choke, used when the engine is cold. Pull the red knob for choke.
  • The " Hot Start " Lever, used when the engine is hot. Pull the lever to lean the fuel mix when the engine has been running.
  • The de-compression lever, always used.
  • The throttle, used to prime the cylinder.
Don't kick, instead, push the kick lever downward. You will feel the back pressure as the piston is going upward on the compression stroke to the point the pressure is great enough that the kick lever "locks up". You are very close to TDC. NOW, pull in the de-compression lever. Push the kick lever a little bit more to get the piston past TDC. Release the de-compression lever. Give the throttle a 1/4 turn then let it snap closed. A diaphragm in the carb gives a shot of gas when this is done. DO NOT do this multiple times because you will flood the engine. Leave the throttle closed when kicking. Give a strong kick through the full sweep of the kickstart lever. Quickly get your foot off the kick lever at the end of the kick to avoid any chance of "kickback" from a backfire. It can be very painful, and can even break a leg. I am serious about that. Repeat the process (but without the throttle priming), until the bike starts. A good battery, a clean spark plug, a clean carb and clean air filter will also aid in starting.

Top rating for this answer? Thanks!

Posted on Jun 11, 2009



  • 867 Answers

SOURCE: Thanks for all the tips on this CRF250R Honda but

i dont know what all you have tried so far, but check the fuel filter, usally in the tank above petcock. the compression seems fine as you had to bump start it in third gear. you can feel the compression of a bike when pushing it in gear, like a bike with bad compression you could push in first without wheel locking

Posted on Sep 10, 2009

Testimonial: " lots of gas , injector cleaner in the gas, spray cleaned up carb in frame,pulled of valve cover cam looks burnt blue in colour lack of oil? valves "


  • 1 Answer

SOURCE: Stalling out, when not completely upright

My 2003 has a cutoff switch on the kickstand.

Posted on Oct 11, 2009

Fabrice Wolters

  • 331 Answers

SOURCE: i have a 1974 dt 250 same as an dt 360 the bike

Compression is too low!

Replace the piston rings.

Also check continuity from engine to frame till high-tension coil...
Check if breaker points aren't dirty ( clean out with fine sandpaper )
Check breakerpoint settings

Posted on Nov 01, 2009

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1 Answer

Yz125 2005 not get fire

Its quite a brief description of issue but any way I assume it is not starting???

You need 3 things to have a running motor 1 Spark at plug test this by removing plug connecting it back to the plug lead lay it on motor and kick bike over to see or not the spark, 2 fuel getting through to spark plug... test this by smelling and feeling the spark plug immediately after kicking it over should be wet and strong fuel smelling... 3 compression there are special tools for this but a simple back yard test is remove spark plug put your finger or thumb over the hole the plug came out of and gently kick bike over if your finger is not forced off instantly and you can resist some or most of the pressure when kicking it over then you have nowhere near enough compression...

This at least will give you diagnosis to know what to investigate further to get the beast to fire... Good luck


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1 Answer

2003 yz125 wont start

Not much info to go by, but i'll give some things to check. Got fuel? Got Spark? Got Compression? If you have all these things, after kicking several times, pull plug to see if the plug is wet. If wet dry with compressed air, ground plug on head bolt or use spark tester, Kick engine over while watching plug, it should spark. If not replace and try again. If still no spark, check kill switch with ohm meter to make sure is working properly. If still no spark you will have an electrical issue with either the CDI Box or Stator. If the plug was dry without fuel, pull fuel line from carb. check to make sure fuel is running, if not check fuel shut off valve. sometimes the shutoff valve will clog up. If all is well it has to be a clogged carb.. Good Luck

Dec 05, 2010 | 2003 Yamaha YZ 125

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2003 KTM 250 SX won't start. When you kick it, it starts to fire but never turns over. I accidently put the wrong gas in it. It takes 60:1 but I didn't put enough oil in it. It died while I was riding it....

If you have run the engine with too little oil then there is probably damage to the piston / rings & / or bore
Remove the exhaust to have a look

Ride Safe

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My yz125 dosnt start was running died out when

check the compression with a compression tester. you may have burnt the ring out on the piston. if you don't have a compression tested you should buy one and test is right but if you remove the spark plug and stick your finger over the hole while you push the kick starter down it should force fully push your finger off. if so you have compression if not then you don't have compression and need to redue the top end.

if you have compression check for spark by taking the plug while it is still out and plug it back into the wire and rest the tip of the spark plug or side of it on the head and push the kick starter again. you should see the spark plug spark at the tip. if so it's good and if not you may have a bad coil or something in the ignition system.

but check that and et me know and i can further assist you.

Nov 30, 2009 | 2003 Yamaha YZ 125

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yeah something you wanna check next, compression. if you can get your hands on a compression tester.

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YZ 125 isn't getting fuel into it's cylinder

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Yamaha yz125 wont start...

you should try cleaning your carb i dont know how often you clean your air filter but if you havn't done that you should do it also.after you do that turn the gas on lean it over till gas runs out the over flow and give it choke no gas and try kicking it should be able to just loosen up the clamps on each side of the carb and twist it so you can get to the float bowl,unscrew the four screws and blow it out with a air nossle you can try that before you go through the troubles of taking it off to clean it.

Nov 22, 2008 | 2003 Yamaha YZ 125

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