Question about 2003 Yamaha YZ 250

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I have a 2001 yz 125 two stroker and i just rebuilt the whol bike. i put it back together and i dont get any spark could it be the cdi because i checked the power and we traced it back to the cdi box

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The CDI and electronics on these bikes are pretty robust and trouble free. I am not going to say that they can't go bad but I can say that since the late 80s, I have seen very few bad electrical components on Yamahas and I have been riding and racing Yamahas since 1980. My point is - if the bike ran before you tore into it, it is entirely possible it is something simple like a bad ground wire connection or a connector that has a bent pin or something like that. Also check your kill switch to make sure it's not stuck or electrically closed - just disconnect it for troubleshooting purposes. The CDIs are pretty tough and over the years I have come to have a lot of faith in their reliability. I would start looking into the primary wiring and look for things like I mentioned above. It could also be something as simple as a bad spark plug or the connection right there at the plug boot. I hope this helped at least a little!

Posted on Feb 06, 2010

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If you disassembled the bottom end and did not have a correct flywheel puller it would be very easy to permanently damage the stator coils. As a matter of fact it would be very difficult not to damage them if you pulled it apart the goon squad way.

Posted on Feb 16, 2010

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Well when i put everything together i forgot to put the ground wire on, could that have burnt the cdi out?

Posted on Feb 13, 2010

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1 Answer

My yz 125 started to bogg down when i put my bike in 3rd gear and i drove it back the next day i went to wash it and i tried to start it. it started but bogged right down till it shut off no matter where...


Ii sounds like your bike cuts out when it get`s hot ? If it does this like clockwork then i guess you have same problem as me with my no limit 125 which does exactly that. i have fixed all connectors & cdi but it still does it. Which leads me to believe some ferrite core in the ignition system is going non-magnetic (called the Currie temp) at this "hot" temperature. It can either be the magnets in the flywheel or the core of ignition coil.I only use this bike for trips less than 10km so i live with it. if anybody can shed more lite plz!

Aug 05, 2013 | 2005 Yamaha yZ 125

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I can't get it to start. Put a new plug in and It's not getting any spark.


i dont know what kind of bike your working on?? but it sounds like its your coil or cdi those are the two things that make spark...

Aug 16, 2010 | 2003 Yamaha YZ 125

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Yz 125 2001. starting ploblem after top end rebuild


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Jun 03, 2010 | 2003 Yamaha YZ 125

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You may have not tightened coil and coil wire screws enough. 2 strokers are notorious for vibrating their bolts loose. Bad earth will nullify spark. Check for clean connections on all leads from crank to coil and CDI unit. Is plug and cap 100%. Check top end gaskets if any sign of moisture on sparkplug.

The float pin may be worn and extending out past ends and jamming on carby housing. Take out and roll on flat surface and look for defects. Ensure float tab (bears on needle) is not notched from wear or bent too far. Clean seat and needle are essential, replace if suspect. Spray some carby cleaner thru fuel line entry whilst you have floatbowl off to clear any sediment or debris. (especially fuel scale or air filter foam)
Cheers.

May 04, 2010 | 2003 Yamaha YZ 125

2 Answers

I have a chance to pik up a 88 yz 125 for a hell of a price and the guy says it wont start. No spark. electrical problem. says its the stator. I dont know that. So im asking, what exactly I can do to find...


hello, usually you have 3 things for firing problems, stator and stator pickup coil, or ign coil, or cdi, i have a 2000 warrior 350, i just went through all that, you can buy after market cdi from procom engineering inc. i purchased one for my warrior 76.00 , it advances timing, hotter spark etc.most of the time it is the stator, pick up coil, both are hooked up together in the stator case, left side of motor,warrior cdi usually goes bad, havent heard of cdi on 88 model, may need to check with dealer.

Feb 06, 2010 | Yamaha YZ 125 Motorcycles

1 Answer

I have a yz 125 with a rebuilt motor i put the nuw motor


A very common problem with wet clutches is that many folks do not use the correct oil. The plates in the clutch are sandwiched under spring pressure and there is nothing in the mechanism to release them, so if the oil creates too much "stiction" then the plates can become suctioned together.

I suggest first trying an oil change using an oil designed for use with wet clutches. Then, get a running start, hop on the bike and drop it into gear. Then pull in the clutch and while holding the clutch lever in, rev the motor to break the plates loose. If this fails after a few attempts, your plates could be rusted together - possibly from a leaking waterpump seal or a ride through deep water. A simple tear-down of the clutch will tell the tale and this can be done without buying any parts if you are careful.

Nov 08, 2009 | 2003 Yamaha YZ 125

1 Answer

I have a 2001 yz80. The spark seems weak. I tested the coil and its fine. I tried it with the kill button disconected, it didnt help.How do I test the stator and cdi? Am I on the right track?


yes buddy the only way to test the cdi is too put on another bike and if it was the stator it wouldnt spark and yes you are on the right tracks but maybe it could be the plug does it run brilliantly

Nov 06, 2009 | 2003 Yamaha YZ 125

2 Answers

Yz125 no spark


G'day i am a . YZ 125 j ...lets see now! You could perform these tests yourself.Check your plug CAP,if in doubt replace it with a new one. Take the below ohm figures and see if they match up. Pulse coil: white/blue and white/red= 310 ohms. low speed coil: Green/white and Black/red= 900 ohms. high speed coil: Green/blue and black= 55 ohms. hope this has helped in some way to helping you solve your problem.If it has please leave feed back.Ride hard , see ya,Tabbycat

Jul 22, 2009 | 2003 Yamaha YZ 125

1 Answer

How much shuld I ask for???


Without bent forks the bike would sell for about $1500. With the shop charge of $900 to fix the forks and a buyers hesitation to purchase a bike with problems, it will probably sell for $500 as a fair price.

I don't get paid for my answers but I do take pride in them, and I am only trying to help. So if you will, > > A “very helpful” rating for this answer? Thanks!

Jun 13, 2009 | 2003 Yamaha YZ 125

4 Answers

What spark plug for yz 125?


I have a dennis kirk book, the correct spark plug is a --BR9ES--(NGK)

i always used SAE 10w-30 oil on all my dirtbikes,
no transmission fluid

for the chain you should move the back tire back until the chain is at a snug tension

Apr 21, 2009 | 2003 Yamaha YZ 125

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