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Discussion Starter · #1 · (Edited)
Brought home the father-in-laws 1988 TRX 300 2x4 as it would not run. As I was trying to figure out what was up, I did the usual pull the plug and see if I had fire by kick starting because the battery was DOA. No fire, though it had been running the last time he rode. Just for kicks, I hooked up a jump pack to the battery and attempted to turn it over. I was encouraged when the lights came on and I got a clicking sound coming from the starter solenoid. I then took off the coil, cleaned it, cut the wire back a bit, and reinstalled the plug boot. I replaced the POS champion spark plug with the correct NGK. I then cleaned the two 15A bottle fuses and their holders. I took off the carb, knowing it was a mess and cleaned it. I put it all back together and checked for spark. Not surprisingly, no spark. However, what did surprise me was that when I hooked up the jump pack, I am no longer getting headlights or a click when I push the electric start button. As far as the no spark, I'm sure I'll have to get a new CDI. However, if it is not getting juice along with the rest of the electrical system going up to and including the headlights, then a new CDI will not really help, unless the headlights go through the CDI. I did bang on it a bit as was suggested in some of the forums. Perhaps this did more harm than good. Any suggestions, recommendations, or opinions would be appreciated.
 

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Hey there - my name is Steve - I'll try to guide you through this

First - the vehicle has an electrically excited CDI and needs a good source of 12vdc to run - that means you got to have power to other things before you get spark

So - from the battery you go through the fuse on the red wire (don't bother with the fuse with the in the pink/white wire) - power goes to the main switch and when the switch is on the black wire is the hot wire - the black wire goes to starter button, the kill switch and the light switch. If you get lights and a click when you push the starter button you are half way to fixing it

At the handlebar kill switch you have to get power to the black/white wire - the B/W wire turns into a blue/white wire at the wiring harness connector and it (the Blue/White wire) goes to the CDI unit - so check for power on the blue/white wire at the CDI unit - if no power, trace the circuit to find out why

If you have power on the blue /white wire, then you need a neutral light - if no neutral light, then you need the clutch switch closed (pull in the clutch lever) or the starter will not spin - if the starter spins, then look for spark - if no spark, then the CDI unit, coil or the pulse generator is bad - coils don't go bad very often - CDI units and pulse generators are about 50/50 (the pulse generator is part of the alternator)

Make sure you have power on the black wires & the blue/white wire at the CDI
Make sure you have a good ground on the dark green wire at the CDI unit
Check for AC voltage (no specific amount, just an output) on the Blue/Yellow wire at the CDI unit (meter set on ACV and engine cranking)
Check for AC voltage (no specific amount, just an output) on the Yellow/White wire at the CDI unit (meter set on ACV and engine cranking)
Check for 12 VDC on the Green/RED wire at the CDI unit
The signal to fire the coil is on the Black/Yellow wire at the CDI unit and cannot be measured, but you need a good ground on the green wire at the coil

Hope this helps
 

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Discussion Starter · #3 ·
Steve,
Just wanted to thank you for the game plan. I very much appreciate the specifics. I'll keep you posted, but it will likely be in the weekend prior to being able to disassemble the machine to a point where I can trace the wires that you have so diligently detailed. One question, I have been attempting to check the bike by placing the jumper cables on the apparently DEAD battery. I'm wondering if I should disconnect the battery and hook up the jumper cables directly to the disconnected ends of the battery cables. What would be your suggestion?
 

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If the battery is completely dead, it should make no difference if it is in or not, but if the battery is just extremely low, use caution - a small battery can be charged with a larger battery, but there no charge rate regulation - the smaller battery can charge too quickly and either be damaged or blow up. If using jumper cables connected to a car battery, it is best to disconnect the quad's battery and just connect directly to the wire terminals. Also. if jumping from a car battery - do not have the car's engine running - just the battery is sufficient.
 
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