250es wiring harnesses

[dustrunner]

Are 85 and 86 250es big red wiring harnesses the same ?

[350for350]

No The CDI plugs are for sure different. I'm not sure about other differences.

[ps2fixer]

If I'm thinking right they are more or less the same discounting the CDI plug. 86 has the common 4+2 style CDI, while the 85 has the round 6 pin one. That connector was only used around 84-85. There might have been a connector or two changed, probably best to compare what you have vs photos of the opposite year.

Just for giggles, why are you looking at a wire harness? Maybe it's an issue with some component? Just hate to have you replace parts for no reason.

[dustrunner]

The harness is all hacked together and I cant get spark...Funny tho, I heard it run a few month's ago, then a person bought it and than sold it to me . lol. pics later . I hate electrical problems !

[ps2fixer]

You have a multi meter and basic understanding on how to use it right?

From what I've seen, 90% of the hacked up wire jobs is someone "trying" to fix a problem that isn't in the wiring lol.

Here's the basic specs for the electrical parts (assuming good connections etc in the harness)
Primary Coil: 0.16-0.2 ohms
Secondary Coil: With Cap 7,440-10,760 ohms, Without Cap 3,690-4,510 ohms
Exciter Coil: 50-200 ohms
Pulse Generator: 290-360 ohms


Here's a list of the CDI wires (check them at the plug to device for connection)

Blue/Yellow: Pulse Generator
Light Green/Red: Safety (Neutral) - Grounded while in neutral
Green: Ground
Black/Yellow: Coil
Black/Red: Power (AC Alternator)
Black/White: Engine Kill (Grounded = Off)


Hacked up wiring is no fun, but checking those 6 wires atleast tests if the CDI is hooked to what it needs. Let me know if something doesn't have connection and such. The lot of the wiring is related to the lighting, charging, and battery.

[dustrunner]

.Im not good with multi meters so I took my running 86 harness and most of my running components off and swapped and after a long 2 days I got spark. some engines have 4 wires for the reverse switch and same have 2. you must have a neutral signal at the dash light to get spark as well as a good stater and cdi. the regulator is not needed for this test. the harness has a few wires I need to play with . I then took a trx 250 key switch and plugged into my good harness and no go. the plug in has a green and black wire as opposed to my original atc red/black wire. so apparently something is different inside the switch. put my good switch back on now no spark again..taking the rest of the night off...wow

[ps2fixer]

For the ignition switches here's what wires are connected at each state.

250ES
On = Red + Yellow/Red
Off = Black + Green

TRX250 (guessing 85-87)
On = Red + Black
Off = Black/White + Green

The "off" wire shorts the ignition wire (black or black/white from above to frame ground/green), no connection = spark so just leaving the ignition switch disconnected will get a machine that can be kick started. Electric start won't work as the other two wires are needed to pass though the power for lights etc.

Also, yes the machine has to be in neutral for the CDI to allow spark. The reverse switch on that machine is purely for the indicator only. Also little confused on the 2 wire vs 4 wire reverse safety switch, it's only two wires that run along the back side of the engine to the bottom where the switches are, or are you talking about the dash light plug?

Here's the safety switch sub harness for reference (86-87 style, 85 is similar though)
https://www.ebay.com/itm/Honda-ATC-250ES-250SX-Neutral-Reverse-Sub-Harness-32410-HA0-010/113398415953?hash=item1a67128251:g:UyIAAOSw1rpb-fvO:rk:1:pf:0

Anyway, if you sometimes get spark, and sometimes not while not changing anything about what's connected suggests to me a bad connection or failing CDI box. Connection points I'd focus on are the CDI plug and engine/stator plugs. Also sometimes people get a situation where electric start = no spark, but kick starting it works fine. I believe those cases were caused from a weak or dying CDI box.

[dustrunner]

my running 86 has only 2 wires going to the reverse plug below the kick starter. this engine im trying to get going on an 86 frame also has " what looks like " a small gm car temperature sending unit in front of it.

[ps2fixer]

Can you get any photos of it by chance? Maybe it's a late 80's TRX250 engine or something. Looks the same engine wise, but there's some interchange problems (output shaft offset being one issue if I remember things right, it is atleast for a 250sx). I haven't gone into the TRX models very much, so it would be good to learn what the engine is from. I suspect the engine serial number would help ID it with a google search.

If I have the right connectors, I could make an adapter for you for a reasonable price, so you don't have to hack up the harness more, or just a simple pig tail to convert the harness to the other engine assuming I can learn what the extra wires are for and the pinout of where they go.

Also near the base of the cylinder, there should be a cc size, wouldn't hurt to check to make sure it's a 250, that bottom end design was used for a while on 250's, 300's and 350's in the TRX models. I have a TRX350D 4x4 that has basically a 350x top end and a 250es bottom end. Actually my dad's 450 foreman has a similar looking bottom end too, but it's shaft drive system is completely different since it's 4x4.

[dustrunner]

I got it going. heres a pic of the reverse wiring. 255750

[ps2fixer]

Based on that, looks like you have a TRX250 sub harness there. Here's an ebay listing showing what it looks like. If you don't mind, I could use an overall length measurement end to end to reproduce an aftermarket solution for that machine. Not directly 3 wheeler related, but still helps the cause. Kind of weird they use black on the side that goes to the engine, but in the harness they use gray.

https://www.ebay.com/itm/87-HONDA-FOURTRAX-TRX250-NEUTRAL-REVERSE-SWITCH-WIRING-SUB-HARNESS/181717735112?epid=1141714272&hash=item2a4f3896c8:g:3WEAAOSwNSxVLpZ7:rk:1:pf:0

[dustrunner]

255761 18 " long

[dustrunner]

my new battery is dead, little red wire going to the fuse block by the battery holder is hot. wonder why it didn't blow the fuse ? must be some sort of short

[ps2fixer]

Awesome, the picture is helpful too. I'll add it to my research data.

[ps2fixer]

If a wire is getting warm/hot, that's a pretty huge draw or even a dead short. Might want to look at the fuses, maybe someone bypassed the fuse with a wire or something inside.

I had that issue with a 86 toyota pickup, some guy wrapped a copper wire around the legs of the tailight fuse. My lights suddenly went out (dash lights go out if the tail lights don't work). After checking things over the fuse tested bad, pulled it and found that rig up. Put another one in with out the copper wire crap and it blew right away. Found the running lights wire near the tail light was bare wire for about 3 feet. Did a short term band aid repair on it with liquid electrical tape, but really the whole section needs to be replaced. I actually have everything to build the whole harness =).

Anyway, learning to use a multi meter would likely be a super useful skill, so far all of your issues could have been solved with a little bit of probing around. I should probably make some sort of thread going over the basics of how a multi meter is used. It's super simple in my head, but I've been using one since I was like 14.

[dustrunner]

I popped a fuse yesterday and replaced it so I will check that in the am. [ATTACH=CONFIG]255767 . gonna start here. this wire goes to the reverse switch and also the starter selonoid..

[dustrunner]

gonna start here. this comes from the reverse switch and also tied into the starter selonoid.255768