[tylerjones]

I have a 2002 trx300ex2 no mods except jetted. The quad was running, parked it the. The next day she wouldn't fire up, the cdi had a loud wistle like a dog wistle and was warm , it produced little spark then quit. So i replaced it and the spark plug wire, new stator and plug with new aftermarket, still nothing. I seen in a thread where it could be the woodruff key. Would it still have compression if the key was worn or broke? Any advice will help i have the manual for assistance

 

[SlammedRanger]

Yes it would still have compression. The woodruff key is only on the flywheel and there is a pickup on the flywheel that sets the spark timing. So if the key was sheared and bolt came loose the flywheel wouldnt spin and it wouldnt spark. Or if it still spins but its turned and not indexed right with the key it would spark at the wrong time and not run usually.

 

[tylerjones]

Thank you for the good information!
I also forgot to mention it will not skid start as well. If that matters

 

[SlammedRanger]

No problem glad to help! Push starting would only work if it was sparking. But no spark no fire under any circumstance. Are you checking spark the old spark plug in the boot to the engine way? Or with an actual spark tester?

 

[tylerjones]

Ive checked with the spark plug out and grounded as well as just putting the plug in my had to see if I get shocked, nothing happens, im trying to figure out how to test the cdi with the multimeter, I cant find nothing on the interweb.

 

[SlammedRanger]

Cdi boxes are very very hard to test. I have never had any success testing one without replacing with a known good one.

 

[tylerjones]

I think I'm going to buy another cdi and try it. I only lean towards that because it was warm the day it went out and it turns out it was replaced 4 years ago from previous owner.
Would the inhibitor box cause no spark as well? 38810-HM3-003 that is the part number

 

[SlammedRanger]

From what i understand the inhibiter box is for reverse rev limit? 400ex's dont have them so im not entirely familiar with them. I would be leaning on cdi also because they shouldnt get warm. That sounds like a blown capacitor if i ever heard of one. If you change it and it works you can cut the old cdi unit apart if you want. Its just a small computer board with big capacitors and resistors on it.

 

[retro]

...The next day she wouldn't fire up, the cdi had a loud wistle like a dog wistle and was warm , it produced little spark then quit. So i replaced it and the spark plug wire, new stator and plug with new aftermarket, still nothing...

Aftermarket usually = china garbage. Hopefully nothing else got fried if thats the case.

 

[tylerjones]

Thanks guys, I picked up a used cdi today off a running 300, Before i plug it up I'd like to check to see if there is current flowing to the cdi, im not sure which wires on the plugs to check and what to setthe multimeter at to check.

 

[tylerjones]

And what if there is no power going to the cdi what should i look for after that

 

[SlammedRanger]

Thanks guys, I picked up a used cdi today off a running 300, Before i plug it up I'd like to check to see if there is current flowing to the cdi, im not sure which wires on the plugs to check and what to setthe multimeter at to check.

This i am not 100% sure of. A quick look at the fsm and the wiring diagram will shed some light on it. You can find the fsm in a few members signatures on here. Not sure which members anymore though.

 

[retro]

You can find a copy of the service manual linked from here:
https://www.hondaatvforums.net/foru...nual-help/50817-service-manual-downloads.html

To answer your question, the Bl/W CDI wire should have battery voltage on it with the key switch on and the kill switch in the run position. See the attached images for more info. Keep us posted if you can?

 

[tylerjones]

Thank you all for the awesome advice! I purchased a used stock cdi from a running quad. It worked! Now it just seems the rev limiter kicks in soon now? Is there anyway I can bypass this or maybe wireing not right, the spark plug coil has two wires can this happen if they are reversed?
Thanks!

 

[retro]

The OEM ignition coil connectors should be marked with differing colors... just match wire color with the connector color. If you can't then you can use a multimeter in resistance mode to verify your connections. The coil ground (-) connector should show resistance with the spark plug cable boot/end, AND show resistance with the positive (+) coil connector, which comes from the CDI. The positive coil connector should NOT show resistance with the spark plug cable/boot end... use those as sanity tests. There might be a photo in the manual somewhere that could help you too.

If the coil is hooked up backwards the secondary winding might possibly unload high voltage into the CDI (frying it) if conditions were right... as for a reversed coil connection causing it to appear to be hitting the rev limiter early...? I suppose anything is possible, but it doesn't sound plausible to me.

 

[retro]

If the reverse light is coming on the inhibitor will rev-limit ya. In that case you'd need to check the reverse switch to see if it is grounding out, per the diagram. Let us know how it goes...

 

[tylerjones]

I checked the reverse light it is not coming on while driving. If i ground out the reverse swith does that eliminate the fwd rev limit or just in reverse?

 

[retro]

If you ground the reverse switch the inhibitor will activate and you'll hit a low rev limit ceiling. So you want to make sure the reverse switch is functioning properly... it should show continuity to ground only while the trans is shifted into reverse gear.