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Discussion Starter · #1 ·
Just picked up an old trx, would like to get it running. Put new gas, cleaned the plug, put in new oil, seems like there's no spark. Turns over nice, just wont fire. Any ideas?
 

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Just picked up an old trx, would like to get it running. Put new gas, cleaned the plug, put in new oil, seems like there's no spark. Turns over nice, just wont fire. Any ideas?
like i said in your other thread..make sure kill switch is in the center '' run '' ..if this is ok..then your stator or c.d.i is bad..check your wiring first..then replace the c.d.i if the wires are ok..the c.d.i is the easy thing to get to..the stator envolves removing the left hand side cover..which..means..draining the oil..pulling side cover..then pulling stator..butttttttttt..before you do all that to replace the stator..ohm it out.if you have a repair manaul..( you can do this check..before you go through all the trouble to pull the stator..then find out it's not bad )..lol.
 

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DO NOT GO AND THINK YOUR REMOVING THE OIL DRAIN PLUG..WHEN IN FACT IT'S THE TIMMING CHAIN TENSOINER....MAKE SURE YOU REMOVE THE RIGHT OIL DRAIN BOLT.
By looking at the pictures in the other thread, the timing chain tensioner is on the back of the cylinder, above the starter.
 

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DO NOT GO AND THINK YOUR REMOVING THE OIL DRAIN PLUG..WHEN IN FACT IT'S THE TIMMING CHAIN TENSOINER....MAKE SURE YOU REMOVE THE RIGHT OIL DRAIN BOLT.
By looking at the pictures in the other thread, the timing chain tensioner is on the back of the cylinder, above the starter.
dang it..stupid allthetimmers is kicking in again..got to many things on my mind helmut..lol..thanks for the save..lol.
 

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there..edited that out helmut..lmao.
 

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Discussion Starter · #7 ·
Is there a type of coil in these ATV's? Forgive me, I've never worked on these before, but old lawnmowers/tractors the first thing I check is the ignition coil. If there isn't one of those I'm leaning towards the CDI because when we pull the starter the "neutral" light lights up which tells me there is power flowing through the system, which would be generated by the stator... correct? Once again I'm sorry if I'm completely incorrect in my definitions and whatnot.

Thanks!
 

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Is there a type of coil in these ATV's? Forgive me, I've never worked on these before, but old lawnmowers/tractors the first thing I check is the ignition coil. If there isn't one of those I'm leaning towards the CDI because when we pull the starter the "neutral" light lights up which tells me there is power flowing through the system, which would be generated by the stator... correct? Once again I'm sorry if I'm completely incorrect in my definitions and whatnot.

Thanks!
Yep, it has an ignition coil. Just follow the sparkplug wire and you will find it.
 

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Discussion Starter · #10 ·
All right, coil's fine. We did all the continuity tests listed in the manual for the wiring and the pulse generator. The wiring is fine... except for the kill switch. So we decided to bypass that. We cut into the wiring leading up to the starter box thingy and connected the green wire and the white/black wire (these two were connected to the kill switch inside). 30 seconds after doing so we realized that the solid green wire in fact leads to the ignition coil... so did we connect two wires that are not relevant? Or should the wires be permanently UNconnected? How do we test the actual CDI? And how much would one of those cost?

Thanks! - I know its a lot of questions...
 

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We cut into the wiring leading up to the starter box thingy and connected the green wire and the white/black wire (these two were connected to the kill switch inside). 30 seconds after doing so we realized that the solid green wire in fact leads to the ignition coil... so did we connect two wires that are not relevant? Or should the wires be permanently UNconnected?
Yeah, they should be unconnected. If they are connected, you will be grounding out the ignition system, just as if the kill switch is in the "off" position.

How do we test the actual CDI?
There is no test for a CDI, other than to replace it with a known good one. Usually you check everything that you can check and if everything checks out good, then you replace the CDI last.
 

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Discussion Starter · #12 ·
Some time for a little update.

So the rotor looks great (assuming it is the rotor) really no rust whatsoever that I can find. Plug is kind of dirty, but nothing too bad. I am assuming the CDI is bad, but I could be wrong just from what I've heard/read. Some pictures




 

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Looks like you were right about the pulse generator and rotor being behind the stator cover at the bottom of the engine. I've never worked on the TRX125, but the TRX200 has a pulse generator and a rotor behind that cover at the top. That's why I thought it would be behind the cover on the TRX125. I don't know why they bothered to put a cover there.
 

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See, this is what I was talking about. This is what's under that top, round cover on the TRX200 engines.

 

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Just picked up an old trx, would like to get it running. Put new gas, cleaned the plug, put in new oil, seems like there's no spark. Turns over nice, just wont fire. Any ideas?
It might be the ignition coil i had the same problem i bought a new carb and oil and gas filter air as well and bought 2 spark plugs and it did not work the my dad said check the coil and it was it it. to check get a volt meter and set it to olms and put 1 prong in where the spark plug goes and the other on where the wire connect and make sure up unplug the ignition coil from the plug and all the wires first the olms should be 20+ if i remember right.
 

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Im having the same issue with my 87 trx125....has no spark....i have my stator out and i found that you test the blue/yellow & green wire and should get around 290-360 ohm.




( Tested the left plug....cant see the yellow on the wire just from how its twisted )

Now if thats right on what to test....i get nothing. Am i doing something wrong...or is my stator bad?
 

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Im having the same issue with my 87 trx125....has no spark....i have my stator out and i found that you test the blue/yellow & green wire and should get around 290-360 ohm.




( Tested the left plug....cant see the yellow on the wire just from how its twisted )

Now if thats right on what to test....i get nothing. Am i doing something wrong...or is my stator bad?
The blue/yellow wire and green wire are for the pulse generator. If you're not reading any resistance between the two, your pulse generator is bad. The two yellow wires are for the stator. To test the stator, check for continuity between each yellow wire and ground. There should be no continuity. Then, check resistance from yellow wire to yellow wire. I don't know the specs for that model, it's probably less than an ohm, but your service manual will tell you.
 

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I hooked it back up to the pulse gen...and checking the the multi meter...on blue/yellow & green im getting no reading. The pulse gen is brand new though. The stator and i got no reading...and both yellow together i get .5 And i don't have a service manual....my brother got this 4wheeler from some guy a few years ago.

Im gonna see if i can find the old pulse gen and test and see what that reads. IF i can find it.

[edit]: Ya....i cant seem to find it.
 

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I hooked it back up to the pulse gen...and checking the the multi meter...on blue/yellow & green im getting no reading. The pulse gen is brand new though. The stator and i got no reading...and both yellow together i get .5 And i don't have a service manual....my brother got this 4wheeler from some guy a few years ago.

Im gonna see if i can find the old pulse gen and test and see what that reads. IF i can find it.
You do have your multi-meter set on ohms, right? I'm sure you do, but thought I would ask to make sure. Make sure you check the wires that go to the pulse generator as they may be broken inside the insulation. I've fixed a lot of ATVs that had a broken wire where the wires go through the rubber grommet into the case. The stator reading sounds about right. You can download a service manual for the 125 in the manuals/schematics section. I think the manual is for the '85-'86 125, but '87 is probably the same.
 

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I def have it set to ohm....lil horse shoe looking thing. Just did a check on all the wires with the multi meter....placing a rod on each end of the wire...where is starts and ends. And got a beep from every wire. So theres no broken wires.

[edit]: I just bought the correct manual from the website you posted for someone else in another post.
 
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