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I just got a 86 honda fortrax and it has no spark. The engine spins but it has no spark at the plug. I was able to follow the black and yellow wire back to a split that one leg goes to something that says HC4 and the other goes to the cdi unit. What is the best way to make sure that this is getting the correct signal from these?
 

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You have the service manual? Great diagnostic in there.
You need to check your stator, pulse generator and exciter coil resistance values.
Spray a bit of starting fluid in the carb? will it sputter and try to run? Likely to be CDI.
Download the service manual and parts links in my signature block below.
Post your findings so we can follow your progress
Do not buy aftermarket knockoff parts—only OEM.
Read this threads
 

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Discussion Starter #3
You have the service manual? Great diagnostic in there.
You need to check your stator, pulse generator and exciter coil resistance values.
Spray a bit of starting fluid in the carb? will it sputter and try to run? Likely to be CDI.
Download the service manual and parts links in my signature block below.
Post your findings so we can follow your progress
Do not buy aftermarket knockoff parts—only OEM.
Read this threads
I have the service manual. It is just slightly blurry. So far I know I have good signal from the engine to the cdi unit. Those two wires into one plug on the cdi. the other plug has 4 wires. One is the black/yellow wire that feeds out to your ignition coil. this pulses and causes the ignition coil to fire off a spark to the spark plug. I have the spark plug out and grounded so that I can see if I am getting spark. So far, no spark. Also no pulse on the black/yellow wire to the ignition coil. I know it is not grounded or shorted as I traced it and I have nothing on it to either the fuel cutout relay or the ignition coil. This leaves 3 wires to test on the cdi. One is the neutral switch. This is needed to crank the engine I think. Not sure. it may just disable spark. I can not read the manual that I got it is slightly blurry. The neutral switch says L?/R so red and something. I can't quite read it. the other two are G/W and Bu/Y i think. Not sure what these go to yet. If I know what the go to I can have a better idea of what to trace them to and what kind of signal to expect. That is what I am currently looking at. Looks like G/W goes to the alternator and Bu/Y goes to the Pulse generator. I am not sure what the pulse generator looks like yet. I think I will go that way next.
 

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Ok RUN/KILL switch set to run?
When you switch on you should get a steady neutral light and the oil light should come on momentarily and then go out.
The neutral light must be on and that’s a common malfunction the wires behind the right footpeg get damaged
 

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Ok. the black and white wire is the run/kill switch. I am not sure if this is supposed to supply 12v to the cdi unit in the run position or ground. I am not sure what color the Neutral switch is L?/red. The light comes on but I am not sure about the signal to the cdi. I may try cutting the neutral switch wire and grounding it for a test to see if it will start. Same with the kill switch.
 

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Here’s the gear change subharness end while I’m repairing it
Reverse is black
Neutral is Light Green
Blue is oil
Dark green is oil ground
150325
 

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Ok. the black and white wire is the run/kill switch. I am not sure if this is supposed to supply 12v to the cdi unit in the run position or ground. I am not sure what color the Neutral switch is L?/red. The light comes on but I am not sure about the signal to the cdi. I may try cutting the neutral switch wire and grounding it for a test to see if it will start. Same with the kill switch.
That gear change subharness is about 14 inches long—you can easily access both ends. Don’t cut that neutral wire unless you have a way of repairing it. Just test all those leads for continuity.
See that special connector on mine? Check out the condition of the light green wire (BTW it has a Red sleeve on it that indicates it connects to a LG/R wire). Anyway my neutral light would flicker when i wiggled that special black connector.
The bullet socket and wire will slip out of there if you lube it with a lot of permatex dielectric grease and tug it with needle nose pliers. Just be careful with it.
then you can repair the wire and slip it back into that connector

You can test your switches by reversing that connector—getting the neutral light to come on by changing into reverse gear! Careful lol!
 

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Discussion Starter #8
Ok. the black and white wire is the run/kill switch. I am not sure if this is supposed to supply 12v to the cdi unit in the run position or ground. I am not sure what color the Neutral switch is L?/red. The light comes on but I am not sure about the signal to the cdi. I may try cutting the neutral switch wire and grounding it for a test to see if it will start. Same with the kill switch.
One more thing ruled out. The neutral switch is working now. The oil light never goes out. I am not sure if it just lights the light or if it disables the engine. I am also going to order a new ignition for this thing and wire it in. Right now with it being hot wired it is probably throwing off my ability to troubleshoot it using the wiring diagram. what a pain. I found the other end of the wire for the kill switch coming from the old ignition and it is broken off as well. Not sure if the kill switch provides ground for the circuit or if an open is good to go on it. No clue.
 

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Ok good progress.
neutral light on steady—gotta have that.
Yes order an OEM ignition master switch—the 6-wire model. Thiscould be part of the problem. Do you still have the main harness connectors attached. Im hoping the PO just cut off the switch subharness wires.

No the oil light will not keep it from starting. But if oil light is on steady then your fan should come on. Do you still have the blue and dark green connectors on the oil sensor?

go to page 20-2 and perform the oil cooling system troubleshooting
Perform fan motor test on page 20-7

and I’ll post a better pic of the schematic. BTW the kill switch has zero continuity until in the kill position—it grounds out the system (page 20-6). That BlW wire does connect to the CDI (page 17-4)
 

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Here’s the switch you need — OEM!
Beware sellers who list “for” OEM and OEM “replacement.
Only buy OEM
150328
150329
 

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Lmk if you can read this—if not ill scan and PM you View attachment 150327
Buddy. You are awesome. That copy is clear enough to read all the letters. I just ordered the 6 wire ignition from Amazon. It was on there for 50 bucks. May take as long as a month to get here. The connectors are still there and have not been cut off. Very nice.
 

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I sent you the schematic
Yeah the Ijoy looks OK but i have to have the real deal OEM stuff. Look under your handlebars do you see a fork lock on the left side? You’ll need a Honda key to fit it

glad the PO keft you the main harness intact — very 😎
 

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I sent you the schematic
Yeah the Ijoy looks OK but i have to have the real deal OEM stuff. Look under your handlebars do you see a fork lock on the left side? You’ll need a Honda key to fit it

glad the PO keft you the main harness intact — very 😎
We live in a very small town. about 600 people. I am not worried about the fork lock for the most part. Now comes the sucky part. The long wait for the part to come in. This will hopefully get the wiring harness complete. Once that is done I will start on the fuel system. The fuel pump is completely disconnected with cut wires. That part will be interesting. In the mean time I am going to teach myself to weld plastic and start putting the plastic back together.
 

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You might need to shop around for a main harness. I had to buy one because mine was all mouse-chewed
 

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Unless I’m overlooking something it’s specified for the OP’s 1986 model; should also work on the 1987 TRX350A. 6-wire connector.
You bring up a great observation tho @shadetree that seller has listed that part to also fit a TRX350D, which it shouldn’t—those D models have a 4-wire connector. Or so i hear I’ve never made it out of 1986 LOLs

You see @mortonarts perfect example of how you need to use those parts links to get the exact OEM part specific to your model and year.
 

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Grrr... i ordered the dang thing off of Amazon and it did not say until it had shipped that it was coming from Chezwan china. Not spelling that right but I don't care. I guess now I will start working on the brakes and the clutch lever. At least I think the two on the left are brake like to the back and clutch line. Not sure yet. I will also adjust and flush the front brakes and get them cleaned up and working. It is about all I can do since my stupid ignition will not be here for a month.
 
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