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Discussion Starter · #1 ·
I have a possible CDI issue on a 1995 TRX300FW. Bought the ATV with an electric non-start issue.

My current CDI is a DB electric. It runs great now. That was my second (aftermarket) CDI box, the first didn't work(kemimoto). I did try some OEM Honda CDI off eBay with no luck, but couldn't verify part number other than what seller disclosed.

I purchased a new sealed in the package Honda OEM CDI from a big online parts retailer. I installed the new OEM Honda CDI, and same symptoms...spark on first crank of starter, then nothing while cranking over the engine, and a couple ignition sparks after letting off start button.

Does anyone know if the 1995 year TRX300FW had a CDI change or something that would cause the correct part number OEM Honda CDI to not work?

The parts retailer has strict return policy. They are reaching out to Honda for me after giving them my VIN number.

Anybody else run into similar problems with getting a new OEM CDI box to run correctly?

Thanks
 

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Anybody else run into similar problems with getting a new OEM CDI box to run correctly?

Thanks
The CDI box is just one part of the system - 90% of spark issues are wiring problems and 90% of wiring problems are ground connections.

First, loosen and tighten all ground connections including the motor mount bolts.

Second check for voltage on the blk/wht wire at the CDI connector - it should not fall below 9.5 volts while cranking the engine
4757

If it's a true CDI, there will be no voltage on the blu/yel wire going to the coil until the engine is cranking - then a 100v pulse should be measured using a peak voltage tester. If it is simply electronic ignition, there will be 12v on the blu/yel wire at the coil and it will be interrupted at the moment of spark - the pulse generator should produce about 3 to 5 volts peak with the engine cranking - the yel/wht wire only provides a frequency signal to the ICM for limiting speed in reverse and over revving - the light green wire is foe sensing when the transmission is in gear and green is ground. All the wires are important, but light green and yel/wht will not affect spark during starting.

Let me know if this helps
 

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Discussion Starter · #3 ·
I'll need to get a better multimeter with peak voltage capability, but that information is very helpful.

I did run through all grounds and checked everything that I can with a basic multimeter.

The ATV runs perfect, but I am using an aftermarket CDI box...

I wanted an new OEM Honda CDI box to put on the ATV and keep the aftermarket as a backup. I purchased this: MODULE, IGNITION CONTROL (CDI)
30410-HM5-505
Honda

When I installed the new OEM Honda CDI box it didn't work! The ATV would not start, and had the same symptoms as the original CDI box that failed (after 26 years I'm guessing).

I can hope that everything electrical is in good shape if the ATV runs good with no electrical issues, so any ideas why the correct, and new OEM Honda CDI box isn't working? Just faulty to begin with?

Thanks
 

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Just faulty to begin with?

Thanks
Faulty out of the box is highly probable since it runs fine with the aftermarket unit - best test is always with a known good unit - if you know anyone with a 94 to 97 TRX300 either 2 wheel or 4 wheel drive that runs and swap their unit with the new unit you bought and it acts the same on their's as yours, then it is a faulty unit.

Was the new unit sealed in plastic inside a sealed box when you got it? I have known shops to put a used unit in a box they just took a new one out of and it ends up back on the shelf and I have seen employees test theirs with a new one and then put their old one back in the box instead of the new one when it didn't solve the problem and they continue working on theirs until they get it running and never recheck the old unit - ultimately the old one gets sold as a new one and it ends up being faulty. Lot's of things happen and depending on the seller it may or may not be returnable.
 

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I loathe CDI issues... I first posted here on these forums years ago regarding a TRX300 and ignition issues. In the end I learned two things:

1. My old CDI had cracks and it would behave differently in below freezing conditions. I believe this was due to moisture that had gotten in, was freezing, expanding and messing with internal connections.

2. never skimp on a CDI, always buy a OEM unit when you can. Aftermarket is nothing but a waste of money and more importantly, gives endless headaches.

I replaced my oem CDI with a aftermarket one right out of the gate it didn't work. So I went down check list to next potential issues: the stator, pick up coil... all wiring. I didn't know it at the time, but the new aftermarket one didn't work, and everything else was fine. I'd have been time and money ahead if I'd just bought a OEM unit to replace the old one.

-DallanC
 
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