03 yz125 won’t start anymore????

Full Sendin It
Edited Date/Time 9/24/2019 9:38am
So last weekend I went riding at my local MX track, I started the bike great with in 3 kicks and it ran fine. Well after riding for about 30 mins I went and took a little break and went back out after that, I started the bike fine, went on the track and I was about to make it around the track when all of a sudden I hit the throttle toward a jump and my bike started to bog down so I let off the gas then it bogged down till it died out. Went to start it and it wouldn’t start. Since that has happened my bike won’t start. Things I’ve done to see if it would start would be, putting a new plug in, checked if the plug had spark (which it did), air filter is clean and oiled, got oil in the bike (fresh oil), mix my gas at 32:1 Castro 927 oil. I recently put on a lectron carburetor on my bike about a week before I went to the track and when I put it on it started with in 3 kicked and rode fine for the 10mins I rode. Then at the track it stopped working. I wanna say it’s because of the lectron carb but I have made it richer and leaner and still won’t start. If I kick it hard enough it will start for like 3 seconds then bogged down and die out. I tried the idle screw and air screw but nothing is working. Anyone know what I can try and do to fix this? Top end has 5hours on it and i have a athena 144cc big bore kit on it.
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kb228
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kb228 9/23/2019 1:11pm
9/23/2019 1:11pm
Put a little bit of gas in the spark plug hole and try starting it. If it runs then something in the carb is plugged up. Im not familiar with lectron so i dont know what that would be. Fuel + spark + air + compression = motor should run.
Paul_Pitzonka
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Paul_Pitzonka 9/23/2019 2:19pm
9/23/2019 2:19pm Edited Date/Time 9/23/2019 2:30pm
Lectron carbs are fairly simple to adjust and tune, they lack an air adjustment screw like a typical Mikuni or Keihin carb... only adjustments you can make are metering rod height (effects the entire fuel curve) the power jet (which is strictly for high rpm tuning), and your slide height... the fact that your bike ran descent for awhile tells me you more than likely have another issue non related to your carb... How’s your compression? If you have good compression I would lean towards a possible air leak or bad reeds ...
Full Sendin It 9/23/2019 3:17pm
9/23/2019 3:17pm
kb228 wrote:
Put a little bit of gas in the spark plug hole and try starting it. If it runs then something in the carb is plugged up...
Put a little bit of gas in the spark plug hole and try starting it. If it runs then something in the carb is plugged up. Im not familiar with lectron so i dont know what that would be. Fuel + spark + air + compression = motor should run.
Will try that when I get home here in a second! Will post the result.
Full Sendin It 9/23/2019 3:26pm
9/23/2019 3:26pm
Paul_Pitzonka wrote:
Lectron carbs are fairly simple to adjust and tune, they lack an air adjustment screw like a typical Mikuni or Keihin carb... only adjustments you can...
Lectron carbs are fairly simple to adjust and tune, they lack an air adjustment screw like a typical Mikuni or Keihin carb... only adjustments you can make are metering rod height (effects the entire fuel curve) the power jet (which is strictly for high rpm tuning), and your slide height... the fact that your bike ran descent for awhile tells me you more than likely have another issue non related to your carb... How’s your compression? If you have good compression I would lean towards a possible air leak or bad reeds ...
When I put the new top end in I got 155psi after breaking it in, I tested the compression when I got home after the problem happened and I had 155-153psi. My reeds have a little light coming in theM nothing major that might be it but they were like that when I replaced the top end so I feel like maybe not since it ran fine after the new top end. Where else could there be air leaks? Would I have to get a leak down tester to find if there is? And also I should add I had to cut some of the Reed boot and air boot off to fit the lectron carb but I still hVe the clamps around them tight

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Paul_Pitzonka
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Paul_Pitzonka 9/23/2019 4:00pm
9/23/2019 4:00pm Edited Date/Time 9/23/2019 4:01pm
Paul_Pitzonka wrote:
Lectron carbs are fairly simple to adjust and tune, they lack an air adjustment screw like a typical Mikuni or Keihin carb... only adjustments you can...
Lectron carbs are fairly simple to adjust and tune, they lack an air adjustment screw like a typical Mikuni or Keihin carb... only adjustments you can make are metering rod height (effects the entire fuel curve) the power jet (which is strictly for high rpm tuning), and your slide height... the fact that your bike ran descent for awhile tells me you more than likely have another issue non related to your carb... How’s your compression? If you have good compression I would lean towards a possible air leak or bad reeds ...
Full Sendin It wrote:
When I put the new top end in I got 155psi after breaking it in, I tested the compression when I got home after the problem...
When I put the new top end in I got 155psi after breaking it in, I tested the compression when I got home after the problem happened and I had 155-153psi. My reeds have a little light coming in theM nothing major that might be it but they were like that when I replaced the top end so I feel like maybe not since it ran fine after the new top end. Where else could there be air leaks? Would I have to get a leak down tester to find if there is? And also I should add I had to cut some of the Reed boot and air boot off to fit the lectron carb but I still hVe the clamps around them tight
Its possible the reeds have gotten worse it’s worth a look... Left Crank seal would be a source of an air leak, as well as your base gasket or case mating seem... As long as the boots on the intake and airbox are cut clean and fit tight you shouldn’t have a problem... A couple companies make nice kits for leak testing two strokes, but you don’t have to spend all that money to test one engine...there’s enough DIY guides out there on how to make one...
Full Sendin It 9/23/2019 4:04pm
9/23/2019 4:04pm
Paul_Pitzonka wrote:
Lectron carbs are fairly simple to adjust and tune, they lack an air adjustment screw like a typical Mikuni or Keihin carb... only adjustments you can...
Lectron carbs are fairly simple to adjust and tune, they lack an air adjustment screw like a typical Mikuni or Keihin carb... only adjustments you can make are metering rod height (effects the entire fuel curve) the power jet (which is strictly for high rpm tuning), and your slide height... the fact that your bike ran descent for awhile tells me you more than likely have another issue non related to your carb... How’s your compression? If you have good compression I would lean towards a possible air leak or bad reeds ...
Full Sendin It wrote:
When I put the new top end in I got 155psi after breaking it in, I tested the compression when I got home after the problem...
When I put the new top end in I got 155psi after breaking it in, I tested the compression when I got home after the problem happened and I had 155-153psi. My reeds have a little light coming in theM nothing major that might be it but they were like that when I replaced the top end so I feel like maybe not since it ran fine after the new top end. Where else could there be air leaks? Would I have to get a leak down tester to find if there is? And also I should add I had to cut some of the Reed boot and air boot off to fit the lectron carb but I still hVe the clamps around them tight
Paul_Pitzonka wrote:
Its possible the reeds have gotten worse it’s worth a look... Left Crank seal would be a source of an air leak, as well as your...
Its possible the reeds have gotten worse it’s worth a look... Left Crank seal would be a source of an air leak, as well as your base gasket or case mating seem... As long as the boots on the intake and airbox are cut clean and fit tight you shouldn’t have a problem... A couple companies make nice kits for leak testing two strokes, but you don’t have to spend all that money to test one engine...there’s enough DIY guides out there on how to make one...
Yea I believe I have watched a diy to make one will have to make one this week and give it a test. I put gas in the top of the cylinder through the spark plug and when I kicked it it started for like 5-10 secs but sounds super rough like it wanted to die but wouldn’t die until about 5-10secs later it did. But also there looked to be white smoke coming out my exhaust not the blueish gray I was getting before and almost looked like white powder was coming out a little bit too. It also sounded like something was loose in the engine. Almost thinking my rod is bad and wiggling around in there. What might cause the white smoke?
Full Sendin It 9/24/2019 8:01am
9/24/2019 8:01am
So I got the top end off and it looks to be alright, looks like i didn’t let the piston warm up fully once or twice but besides that there is no up and down movement on the rod but there is a little side to side movement. Is that bad? Piston has some black spot on the top of it not to sure what from? Maybe putting the gas in the top of it?
Full Sendin It 9/24/2019 8:11am
9/24/2019 8:11am

Anyone know what this part is by the fly wheel? The part in the red circle, looks to be missing a screw and the other one was super loose, idk where the other screw went.... hoping there wasn’t one in it to begin with if there was could it make it into the engine from where it’s at?
Paul_Pitzonka
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Paul_Pitzonka 9/24/2019 8:36am
9/24/2019 8:36am Edited Date/Time 9/24/2019 8:38am
That’s the pickup/ pulse generator that controls when the ignition system fires... Very possible that could be part of you issue... If the screw fell out it may be stuck to the inside of the flywheel as that’s basically a giant magnet, and no there is no way for that screw to make its way inside of the engine...
Full Sendin It 9/24/2019 9:20am
9/24/2019 9:20am
Paul_Pitzonka wrote:
That’s the pickup/ pulse generator that controls when the ignition system fires... Very possible that could be part of you issue... If the screw fell out...
That’s the pickup/ pulse generator that controls when the ignition system fires... Very possible that could be part of you issue... If the screw fell out it may be stuck to the inside of the flywheel as that’s basically a giant magnet, and no there is no way for that screw to make its way inside of the engine...
Well that’s good news that it’s not in the engine😅 I will have to look better to see if I can find the screw, but yea the pluse generator thing was just hanging there and pointing down not even close to where it should of been positioned at. I am going to either buy a screw that size or will try to find it once I get home. Hoping that is the problem! Thanks for the info btw you’ve been a big help!
Paul_Pitzonka
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Paul_Pitzonka 9/24/2019 9:34am
9/24/2019 9:34am
If that was just hanging there I’m honestly not sure how it was even firing...
Paw Paw 271
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Paw Paw 271 9/24/2019 9:38am
9/24/2019 9:38am
It could still fire, but it would be doing so not at the correct time.

Paw Paw
Full Sendin It 9/24/2019 2:38pm
9/24/2019 2:38pm
Paul_Pitzonka wrote:
If that was just hanging there I’m honestly not sure how it was even firing...
Me either tbh, it only had one screw in the bottom part and that screw was maybe threaded in 2-3 threads so it was pointing downwards, I guess it was still able to fire but definitely not at the right time

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