My TRX 125 will only spark one time at the spark plug when you first pull start or push the button on the starter, after that first spark it has nothing. Every now and again it will spark just before the engine stops spinning.

I have changed the plug and nothing happens. Checked the coil nothing is wrong but I even replaced it with a new coil and the same thing. I replaced the CDI box but the new one has to be the wrong one or something because there is no spark at all with the new CDI box I bought. I looked online and the CDI box that I need is hard to find, Does anyone know if the CDI boxes are still being made anymore?

I bought the 125 and it was just sitting in a field. I took it home and cleaned the Carb. out and it fired up and ran. I bought a new fuel tank for $200.00 and a new set of tires for $200.00 and rode it for about 1 week and then the spark issue has happened.

I am lost on what to do I have gone through this thing and cannot figure out what is wrong. I read some people say something about the reverse switch could stop it from starting but I am not sure if this is it or not. I never tore the side cover off and I hate to keep buying parts and just starting throwing them in it until I figure if it is fixed. Has anyone had this problem before? Can anyone help me diagnose this problem? I have a feeling it is the CDI box but no way to test it to tell. Could be the so many other things I do not even know where to start. I been trying to figure this out for a month now. Some one please help me.

Rob

 

May try getting an volt/ohm meter..... see if other ignition part could be at fault.....Test your stator...should be an harness coming out of left side of engine with 2 or 3 yellow wires see if any of them run to ground....none of them wires should run to ground.....then check to see if all of them have continuty to each other....if all good....At the front left of engine head [should say cdi on cover] this is where the pulser genarator is.... take that cover off to see if spring are of the advancer also see if pluser has an air gap between it and the advancer should be around .010..If all is good at this point then take meter to see if an signal is getting out of pulser to cdi[sqaure box] If all is good there then next see if all of the test parts are getting signal to cdi..This should narrow down the other test that will come next...Get back with us here for an update.PS May unplug kill switch first before testing any of these TO make sure not an faulty switch ....Good Luck

 

I might have a 87 instead of a 86. I do not have the CDI cover on the side of the engine. I have a cover there but all that is behind it is the cam gear and timing chain, nothing for the ignition. So I am guessing that it is going to be a 87 instead of a 86.

I checked the 2 yellow wires and none of them run to ground and have continuty. I unplugged the on/off switch and still the same with the spark. I have not been able to really test the CDI box because I have no clue on testing process. I have read that there is no test process for it that you test everything else and if everything else is good then go ahead and replace the CDI box.

I hear that there is the neutral and reverse switch that if they go bad then that could be the problem. I do not even know where this switch is at to test it. Everything that I have tested has checked out good, all the wiring is good. I get spark so that says everything is connected properly but something is in the system that wont let it spark more then once and I can figure this out.

Any other suggestions? I am stumped and the worse part is I am a mechanic and worked on everything from lawnmowers to construction equipment so I am use to trouble shooting but I never encountered a problem where I would only get 1 spark at the beginning of the start cycle and nothing for the rest of the engine rotation.

 

hey man, ive spent the last 6 months working on 2 of these things i can strip them to frame and redo everything, just wanted to let you know, i have a complete parts bike, and have had a similiar problem, although i cant recall how i fixed it i just kept trying diff things, point is i have a complete harness with all the elec components, they work, from swithches to everything that comes off them, not great with the actual names of things but i think i could help you solve you problen over the phone, if not i can send you a complete new harness w/ all components, i have my favorite so this stuff will just rot away, id ratherr help a brother out if i can, i dont want crazy money, just cover shipping ect. if we cant trouble shoot it. let me know and ill give #.
like the man before the wirers are greenn and blue that come off the 125cdi , they go to the harness a ground goes from the harness and goes to the starter, the yellow wires come out a the transmission, along with the gray, blak and red ect.
ltmeknw

 

Hey man thanks a lot I appreciate you going out of you way like that I did not expect it so thanks. But last night I went ahead and went through the whole thing again and what happened is the key switch is jacked up. You can turn it on and everything would work at first but it would ground out when you tried to start it and only let it spark one time.. It is actually really weird because if you test the key switch with a multi meter it will tell you that everything checks out good. I ended up hooking the black and red wire to it and it has a lot of spark and I even rode it today. I do think that it needs a carb rebuild because it took me a while to get it started once it started it ran great. It wont idle on its own so you have to stay on the gas a little bit but I just cleaned the carb when I got it and it was super dirty I think I might have to just buy a complete rebuild kit. But I am happy that I got it going, I got it for my fiance and the kids to play around but I end up using it around my yard a lot and now I can go back to using it again.

Now that it is running where can I get the parts for it? like the CDI box does not seem to be for sale no more and I am scared that if I need parts later on in the future that some of them wont be available.