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2003 yz 125 no start

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Embarrassed 2 say I need some helpicon1.png here. I picked up a 03 Yz125. The bike was sitting for 9 years, I was told all was well when parked. So I drained fuelicon1.png, flushed tank, took carb 100% apart & cleaned everything! It idled ok but would die under load as if the fuel was shut off. Now it won't even start. Have 160psi of compression, good fuel, strong spark, float level is good, power valve isn't stuck, no exhaust restrictions, fuel tank vent ok . Plug is wet so I know its getting fuel. Who can be the man & help me out here? 

 

Note: It will not start off of 2+2 carb cleaner either.  Tested whole electrical system off of service manual specs.  Primaryicon1.png coil is testing bad @ 0.00 ohms spec is 14-.22 ohms.  I know that means there is a short in the primary coil.  But it still has a great spark...  Secondary coil is testing good @ 9 ohms spec is  6.7-10.1

 

Any one have any input on the coil situation?  Can a bad primary coil affect spark timing?

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Well, don't be embarrassed about that description, good job.

Its commonly thought that even tho you see a spark at the plug outside the engine, it can be a different story when the spark energy is required to fire a plug inside the cylinder under compression.

Have you checked the reeds?

Check the intake manifold o ring for good measure.

Be sure anything ignition system related with a ground point is clean, plug connector pins not corroded, rule out the handle bar kill switch being a problem.

Be sure the plug cap is firmly affixed to the end of the coil wire and not showing corrosion.

Are you calling the CDI the primary? If so, Its the brain of the ignition system, timing, rate, duration. Bike won't run if its bad. If you check everything else and it its still coming back to this, see if you can find a known good one to temporarily swap out with yours to definitively make a diagnosis on yours.

Edited by Trailryder42
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Has brand new boyesen reeds. intake seal is good.  Also has a new stator side crank seal too.  Checked all the electrical stuff u mentioned so far.  In the service manual there are two tests for the coil 1. primary side (ohms testing the terminal on coil to ground) 2. secondary side ( ohms testing the terminal on coil to plug end).  I got a used cdi off of ebay & it made no change...  I tested the coil on my 2stroke jet ski & that coil had a 0.00 reading also.  I know its a totally different part & all.  But it runs. I may just pull that coil & try it on the bike.

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Rather not go to the dealer.  Probably gonna want to just shotgun a bunch of parts at it...

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Well took it to the dealer.  They say they worked on it for 3 hours & would like to replace the fly wheel.  There reasoning is because there are some marks on it.  They say the spark is intermittently occurring.  This is not true.  It has spark all the time.   I made the marks on the flywheel when I tried to remove it to check the keyway.  Before buying a puller to properly remove it...  The bike didn't run prior to my damaging the fly wheel...  P.s. it's not even that bad. They want $300.00 parts & labor to do this with no guarantee it will fix anything. So now I'm back to the drawing board & out $95.00

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Hmmmm.......... a tough one. When you said you cleaned everything, and then it would start and idle, does that mean that it would die after touching the throttle? If you could originally get it to idle, see if you can replace the sparkplug and return back to that time when it would at least idle. Then we can help from there. You didn't try to use a three jaw puller on the flywheel did you?

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It would die when letting clutch out.  You could get past it some times & it would seem to run great till you shifted to second.  Then it would die...  You would coast to a stop & would re start just fine.  After I had the carb apart for the 5th time it stopped starting all together.  You would think that would point to a carb problem.  But there isn't much to it & nothing looks out of order.  I have 3 new plugs & nothing I have done makes a difference.  I think it needs a stator even know it is testing good.  I think there is some kind of spark timing issue going on here.  It won't even start off of 2+2 carb cleaner.  everything will fire up on that stuff!!  Dropped it off at another shop after getting hosed at power sports east.  Guess see what this guy comes up with.

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