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trx300 4x4 changed CDI now dont start

2K views 17 replies 5 participants last post by  shadetree 
#1 ·
91 model I recently got for my son. it needed a lot of work, but we got it running without much trouble. However, it had an intermittant problem as it would die after running for some time. If I wiggled the cdi box, it would restart and run awhile longer. the wires were cracked and broken at the back of the plug so I ordered a new cdi box that came with a new pigtail, but the wires were different color. no problem, I just wired it back in the same position as the old one and soldered the connections. It would not fire up. No fire to the plug. I download a repair manual and follow the instructions for checking the cdi module and find that the neutral safety switch has continuity when the manual says it should not. even if I unplug the wire from the switch at the bottom righthand side of the engine, it still shows continuity to ground at the cdi. Sounds like the wire is shorted to ground, right? Can I run a jumper wire from the cdi straight to the neutral switch? Im wondering why it suddenly went bad, it ran pretty good before, other than the shutting off problem. I made a small problem into a major one.:icon_cussing:
 
#2 ·
your turning the key on, and your not getting a neutral light on the dash ?, if the neutral light is not coming on ?, it won't fire at all. the neutral switch must be hooked up at all times. turn the key on ( this is for testing only ! ), touch the neutral wire to the engine/frame for ground, light come on then ? if so ?, you either have a bad nuetral switch ( common problem ), or, a bad diode under/inside the black box under the handle bars, 10mm bolt holds the plastic door closed, the diode is inside there. pull it out of the connector, take a paper clip, install it in the connector ( this is temporary ! ) turn the key on, neutral light come on then ?, if so ?, the diode is bad. and welcome to the forums.
 
#5 ·
It is an aftermarket CDI from ebay. The neutral light comes on but doesnt fire at the plug. I even tried the old cdi that worked, although inconsistently, and still no fire. next, I will check the run/kill switch with ohm meter. anything else to check? Thanks for the welcome and help!
 
#8 ·
Bought a cdi off ebay, same problem you're having. As soon as I plugged in the aftermarket cdi I didn't have a neutral light. I plugged in the original cdi and had neutral light. Get you an original OEM or Ricks Hot Shot CDI. They are the only ones that are any count.
 
#11 ·
I am really glad to hear "you" say the Rick's Hot Shot CDI is a good choice , I have one in transit right now and hope to get it today ----------- I am just looking for more rpm's and maybe fix the problem of having to hit the starter button one time and let it go = it only fires one time if you hold the starter button in , if you hit the button and let off immediately it will continue to fire , start up and run , I have had this problem on at least 300 I have or had before
 
#9 ·
The thing is.... I have the neutral light on but no spark at the plug. I ohmmed the kill switch, it works fine. I changed back to the old cdi and nothing. Neutral light is still on and it will go off when I put it in gear. Going back to my first post - the manual says there should be no continuity{open circuit}on the green wire to ground when the shifter is in neutral. This one has continuity to ground like there is a short in the harness to ground. even if I disconnect the neutral switch connection at the transmission, i still get the closed circuit at the cdi. HELP!!!!!!!
 
#10 ·
the neutral light is '' hot '' at all times when the key is on, and your in neutral, once you shift to another gear, your grounding the neutral wire, and this is what turns the neutral light off.
 
#12 ·
Here is where I'm at now...when the atv is in neutral, the light is on. When I push the starter button, the reverse light comes on. No spark at the plug wire. I checked everything according to the manual...cdi box, on/off switch, coil and plug wire, neutral switch, ac sensor, diode. Everything checks good, but will not spark. Should I look for a new wiring harness?
 
#16 ·
reverse light should never come on when electric starting, if it is ?, then this is grounding out the neutral light ?, and it won't fire the plug. oil temp light comes on when you first turn the key on, then goes out after a couple secs. only neutral light should be on at all times when the key is first turned on, until you shift gears.
 
#18 ·
here is how the neutral light and reverse light works, key on, both the neutral and oil light comes on, once the it sits there for a couple sec's ?, the oil light should go off, they all work this way. if your reverse light is staying on at all times ?, this tells me your neutral/reverse switch, or the connections leading to it are bad ?, not connected cleanly ?. the neutral light wire going to the switch is hot at all times when the key is turned on, when you change gears, like going to 1st ?, it grounds out, this turns the light off on the dash. the diode only gives power to neutral light, has nothing to do with reverse as far as I know ?.
 
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