Need help with 86 TRX250 CDI

149 Views 6 Replies 2 Participants Last post by Here 2 help, 29 d ago

Leroy1025

Discussion Starter · 1 mo ago

Hey guys. New here. I’ve been searching this site and found that CDI units are specific to certain models and not all interchange. Here’s my issue. I have 1986 TRX 250 ( utility model). It’s an old beater but it ran when I got it a year ago. Recently it has started running rough. I tested spark with a tester and found it to be weak and intermittent at times. Replaced the coil. No change. Replaced coil with a known working coil. No change. Next I tested the stator. It tested good and is charging the battery. I’m down to the CDI box. Ordered a Ricks Motorsports 15-615. It wouldn’t start with that one but would run with the old one. So I sent it back and confirmed with them that that it was the wrong one. They sent me part number 15-617. Same result. It would not start, but will still start with the old one. They would not let me return the second one, so I ordered one from DB electrical. Part number IHA 6063 which is supposed to be the equivalent to 30410-HA8-003. I got the same result again. It will not start, but when I put the old box in it will run intermittently.
does anyone know if these boxes are correct or am I installing the wrong box? The current unit is an aftermarket, and does not have any numbers on it, so I have no way to identify it. in my searching I’ve noticed that a lot of sites recommend the same box for the ATC 250. Did they share the same box or do I need one specifically for mine?
Any help would be greatly appreciated. Thanks.

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Here 2 help

· #2 · 1 mo ago

The part was the same for:

Honda ATV 1987 TRX250 A
Honda ATV 1985 TRX250 A
Honda ATV 1986 TRX250 A
Honda ATV 1987 ATC250ES A
Honda ATV 1986 ATC250ES A
Honda ATV 1987 ATC250SX A
Honda ATV 1986 ATC250SX A

If it runs, did you try changing the spark plug?

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Leroy1025

Discussion Starter · #3 · 1 mo ago

Thanks for the reply.
I did change the spark plug a few months back when I did an oil change but like any electrical component I suppose it could be bad. I’m still puzzled as to why the other CDI boxes won’t let it spark at all but the old one will spark. Sometimes I can ride it around for a few minutes before it starts running poorly, and sometimes it will only start and idle, and as soon as I touch the throttle, it sputters. I will change the plug again just to confirm that it isn’t the problem.

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Here 2 help

· #4 · 1 mo ago

I finally got some time to investigate a bit deeper on this issue.

In 1986 there were 3 TRX250 models offered:

The TRX250ES (which is what you have) ES was electric start and shaft drive - also known as the BIG RED
The TRX250SX - electric start chain drive sport model (no racks)
The TRX250R - two stroke chain drive 'race model'

Now to discuss the spark issue:
The ignition is DC - a low battery will cause erratic running beyond that, the CDI unit, the coil, the spark plug cap, the spark plug and electrical connections are usually the culprits.

The only purpose of the stator is to produce AC voltage to charge the battery. The TRX250 you have has a separate pulse generator outside of the flywheel. Now the job of the pulse generator is to trigger the CDI unit to discharge through the coil to make spark.

What you need to do it check the average voltage of the DC circuit while running and check the peak voltage of individual components upon failure.

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Leroy1025

Discussion Starter · #5 · 1 mo ago

Great suggestions! You are a TRX library! I will look deeper into this tomorrow and report my findings. Thank you.

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Leroy1025

Discussion Starter · #6 · 30 d ago

Ok. So I checked battery voltage. It was at 12.7 Volts. I put a trickle charger on it overnight and started today with 13.1 Volts. I also installed a new spark plug. Still the same issue sometimes runs OK , sometimes sputtering. With the engine, idling, I started checking, pulling, and wiggling wires. wouldn’t you know it, I found a wire that would change the tone of the engine when I would wiggle it. Someone before me had installed a fusible link that had a bad connection and stuffed it behind the rectifier where I couldn’t see it. I replace the connector and ta-da!! it runs great!! Just out of curiosity I installed the ricks motorsports, CDI box, and it still will not run with that box. I am still puzzled by this, but at this point, I don’t care.
Thanks for all your help.

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Here 2 help

· #7 · 29 d ago

The Rick's CDI unit (made in China but has a warranty) may be bad out of the box ask to exchange it and see if the next one works.

Glad you found the problem. It reinforces my mantra; 90% of all electrical problems are connections and 90%of all connection problems are grounds. Your problem was in the smaller 90% of electrical problems.

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