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Discussion Starter #1
Hey guys I have a 2001 300ex that lost spark, or mostly lost spark. When turning over, I get a couple sparks, and then nothing. Come back later, maybe get a few sparks again, then nothing. The plug had only been used for maybe 5-6 rides, was new last year, but tried a new plug and no help. Replaced cdi box with 2 other boxes, one used and one brand new, still no help. Tried 2 other coils, one used and one brand new, still no help. Tried another pulse generator and stator (both used)- no help. All 3 coils measure properly per the service manual. Both pulse generators and both stators measure properly per the service manual. Took measurements right at the cdi plugs to also test wiring. I'm getting 12V on blue/white wire right at the cdi, the 12V supply is lost when either the kill switch or key switch is open, so I believe both switches are working. Green wire is grounding properly when not in reverse, and opens when in reverse. I even disconnected the wire at the reverse switch and grounded it to be sure. I'm about out of things to test or replace at this point. Any further ideas? There is just not much to the ignition circuit, so this is getting frustrating.
 

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Discussion Starter #2
Oh, and I took the original cdi and the used one I bought, and tested in a 97 300ex, both work fine
 

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You have a seemingly impossible problem that most likely has a simple solution. 93 to 03 were all wired the same, so if you have one that you can swap parts to, swap all the parts (one at a time)from the non running one to the running one until the running one will not run - replace the part that caused the running one not to run - if you have swapped all the parts except the stator, install a new stator in the non running one.

There is no blue/white wire at the CDI box - you should have 12 volts on the black white wire when the both the key switch and the handlebar kill switch are in the on or run position.

The green white wire at the CDI box should have continuity to ground - the dark green wire is ground - test at various locations - green/white to frame, engine, green wire a the coil. Disconnect the gray wire from the reverse light switch.

One test I'm pretty sure you have not done is to check the AC voltage on the yellow/white wire at the CDI unit - unplug the stator from the wiring harness (2 plugs one with 3 yellow wires and one with a yellow/white, blue/yellow and a green white. The green/white should have continuity to ground - the blue/yellow should have continuity to ground, but a higher resistance than the g/w to ground - the yellow/white should have continuity to the three yellow wires, but the resistance will vary depending on which yellow wire is checked - none of the yellow or yellow/white wires should have continuity to ground - if there is continuity to ground on any of the yellow wires, the stator needs replaced.

If you have 12 volts, good ground and a known good CDI unit, the problem is either the pulse generator, stator, coil, spark plug cap, spark plug or flywheel out of time.

Hope this helps
 

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Discussion Starter #4
First off bud, thanks for the reply. Yes, I have done many of the checks you indicated-

I meant to say blk/white wire, not blue/white. Unplug the 2 wire connector at the cdi, have 12V on that plug- 12V supply on blk/white is lost when key switch or kill switch is off. Gray wire on that connector has continuity to ground when not in reverse, opens when in reverse. This is opposite of what the honda service manual says, but I think the manual is wrong. The Clymer manual states it how I am reading, which I believe to be correct. Disconnect the gray wire from the reverse switch and it will not turn over at all. Makes sense, since the 97 will not turn over at all in reverse.

Green/white wire has continuity to ground. Checked at battery, ground connection near coil, and the engine itself.

Yellow/white wire measures 3VAC while turning the engine over. Disconnected the 3 wire plug at the stator with yellow/white, blue/yellow and a green white wires. Checked continuity of all 3 wires to the 4 wire plug at the cdi. All have continuity.

Yellow/white wire has around 1 ohm resistance to all 3 yellow wires. All 3 yellow wires measure about 1 ohm to each other. All 3 yellow wire open to ground on the stator side

Blue/yellow wire measures 320 ohms to ground at the 4 pin cdi connector. Same measurement as the pulse generator that I took out. I get between 300-400mV peak on this wire while cranking engine. About the same at the original pulse generator was putting out

The machine did give me a couple issues in the fall, where it would just randomly die every once in a while and be hard to start up again. I thought that went away, but maybe not.

While troubleshooting this, at one point I whacked the stator cover a couple times with a dead blow hammer. I suddenly got good spark, started and ran the machine for a few minutes, then it died. Checked spark, and it was lost again. Was able to duplicate this a couple times, and this is what lead me to swap out the stator and pulse generator. It didn't fix the issue, and I have not been able to duplicate getting that spark again. Its back to a spark or 2 then nothing, come back in a little while, spark or 2, then nothing.

I'm an electronics guy, and know my way around in that field, and like you my initial thought is something easy and dumb is going on. I'm starting to lose that optimism now though....
 

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OK - now we are getting somewhere

Then gray to the reverse switch turns on the reverse light when in reverse - it also activates the 'reverse inhibitor' box to limit speed in reverse - the switch is normally open (the neutral switch and the reverse switch are the same part number 35600-HA0-003) - the engine will start in gear (both forward and reverse as long as the LH lever is pulled in and the lever switch closes.

The reverse inhibitor box also interacts with the neutral light circuit to prevent the electric starter from spinning when not in neutral.

Disconnect the gray wire at the reverse switch and see what you get - if not the fix, then swap reverse inhibitor boxes with the running machine and see what you get - just because the reverse light is not on does not mean all is working right. The reverse inhibitor is responsible for turning on the light. A failure of the unit can prevent spark when the reverse light is on or off and it may turn the light on, but not limit reverse speed. Simple test - ground the gray wire and it should turn on the reverse light even when the neutral light is on. The yel/wht wire going to the CDI box from the alternator is basically a 'tach' wire - it triggers the ignition to limit speed to about 2500 RPM when in reverse.

I got a degree in electronics in the 70's which helps troubleshooting electrical systems. I was already a mechanic when I went into electronics. I was not happy working on TV's and radios - in 1975 I got laid off from General Electric and started working on motorcycles, cars, tractors, lawn mowers; whatever needed to be fixed while I was drawing unemployment. In 1978 I rented a gas station and started doing mechanical work full time. In 1981 I gave up the gas station and opened my own motorcycle repair shop. I have had franchises and walked away from them. My forte was repair (not sales), so I concentrated on maintenance and repair. Today I am trying to figure out how to retire in seven years when I am 75 so I can spend time riding my dirt bike and finish restoring my 72 Triumph 650 Bonneville and my 75 Suzuki RE5 Rotary.

Let me know what you figure out - I'm curious as to what ends up being the problem. Do you have a service manual and a wiring diagram?
 

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Discussion Starter #6
I disconnected the gray wire right at the switch and reverse light comes on, neutral light goes out. Will not turn over either with or without the clutch lever engaged. This sounds correct at the 97 will not turn over while in reverse, with or without the clutch engaged. I am pretty sure that neutral switch is normally closed, and opens when you engage reverse. It says the opposite in the Honda service manual, but I think it’s wrong. I have found a couple mistakes in the manual. I also have a clymer which states the reverse switch the way I said.

Got my electronics degree in 2000. I spent a lot of time in the industrial electronics repair field. Mainly AC and DC drives/motor speed controls. Field service and bench repair, start ups, etc. Lots of cool applications, but I was basically married to the job, and had to be ready to respond to emergency breakdowns. Just got burnt out after awhile. Now it’s all hobby, or fixing junk that friends and family bring to me
 

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What Clymer manual are you using? It is wrong for your model and Clymer manuals have more errors than the Honda manuals. I have corrected both from time to time.

The Clymer manual I have is M465-3 (revision 3)

Attached to this post is the ignition circuit and wiring diagram from the Honda service manual and in the next post is the ignition and wiring diagrams from the Clymer manual #456-3
 

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TRX300EX ignition and wiring diagrams from the Clymer manual

As you can see in both sources, the neutral and reverse are depicted as normally open - the neutral closed when in neutral and the reverse closes when in reverse

I can only presume you are looking at the wrong manual or the quad is not a TRX300EX

Providing the VIN would be helpful in determining what model you are working on
 

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Discussion Starter #12
The Cylmer I have is a M456, I assume 1st edition. Looking at the schematic real quick it appears to be the same as yours, at least in the ignition section. I do see what you mean about the switches being normally open in the schematic. My experience with schematics tells me that the switches should both close when in reverse and neutral. My reverse switch is doing the exact opposite. Open when in reverse, and disconnecting the wire, the reverse light comes on, and the machine will not turn over. I recall another thread you were helping, the guy has the same scenario, but I dont remember what the end result was. If both the neutral and reverse switches are the same, I will see what my neutral switch is doing. Can also check the 97, but I won't have access for another week or so (it's my father in laws, and he is out of town). Can then try a reverse inhibitor swap. I had to replace that before, when I first bought the machine. This is certainly puzzling, I've not struggled this much on troubleshooting a quad before.
 

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I feel your pain - I have had vehicles that I felt I would never find the problem, but I persevered and eventually got it figured out - the worst is the one with multiple problems in the same circuit.

Please believe me, both the neutral and reverse switches are normally open. A trick I use to 'fool' the electrics is to simply unplug the wire to the switch and jumper it to ground.

I had an old Honda step thru 50 with a 6 volt system that would not electric start and the owner wanted it fixed. I jumped the battery directly to the starter motor and is spun the engine over (starter motor good) - I applied 6 volts to the solenoid, worked sometimes and sometimes not (flakey - I had to beat the woods to find a new solenoid - found one almost $100) put the new solenoid on and it worked 100% when tested - wired everything up, pressed the button and nothing - the neutral light would kinda flicker a bit each time the button was pushed, but the solenoid would not pull in - I tested voltage at the wire to the solenoid 6.2 volts (it was a new properly activated battery) - why the hell would it not work? I rechecked the wiring diagram - there was no voltage to the starter button unless the neutral switch was closed - I connected a jumper wire (I have many jumper wires with alligator clips on both ends of various lengths and gauges) from the neutral switch terminal to the engine - there was no change in intensity of the neutral light - pressed the starter button and the engine cranked started - I repeated the test several times and it worked flawlessly - I removed the jumper wire and the starter worked one time - I tried operating the shifter and every once in a while when shifted out of gear to neutral it would start normally, but it was like once for 20 shifts - I determined the neutral switch was the problem. Getting a neutral switch was not a problem as Honda is still using the same switch on various models - installed the new neutral switch and there was no change in the operation of the neutral light, but I now closed the solenoid every time the starter button was pressed. During the course of testing, I checked the voltage on the starter solenoid wires - it was 6 volts in and 6 volts out, the problem was no current flow. Voltage is the push (potential) and amperage is the flow. If resistance is high enough, the voltage is there, but current fails to flow. This is exactly what was happening. The neutral light needed very low current to illuminate, but the solenoid needed high current to operate. The neutral light had sufficient current to light, but the neutral switch did not make a positive enough contact to carry the necessary current to allow the solenoid to close.

There have been others and not all electrical, but I never failed to find the cause of a problem regardless of how deep, hidden, obscure or improbable. Sometimes replacement of the offending part is the only and easiest fix. A Polaris clutch is the source many different complaints from driveability, acceleration, and insufficient speed to knocking like a rod is going out. Fortunately, a Polaris engine can be started with the clutch removed to diagnose motor noises. Many times removing the clutch eliminates the noise.
 

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Discussion Starter #14
We certainly seem to think alike, must be the electronics technician blood. Yeah, I did try to unplug the gray wire from the switch awhile back, and jumping to ground- exact same thing, 1 spark or 2 then nothing. Just letting it sit unlugged, will not turn over at all.

I certainly believe you on the switch status. I guess I was/am worried, that the switch itself is built as normally open, but being in forward actually engages the switch. Are we sure this is not the case?

Another thing I'm considering is a bad connection in the 12V supply to the cdi. I don't remember measuring the internal impedance on the cdi, but if it's low, it wouldn't take much of a poor connection to "steal" the voltage. Of course my multimeter being such a high impedance, wouldn't detect a voltage loss in this case, with the connector being unplugged. I need to get that voltage measurement while the plug is plugged in to be sure. I ran into something like this in my mustang, not getting good voltage to the taillights, when a little bit of corrosion occurred on the fuse :)

I think we are getting some progress. Will look into the reverse and neutral switch a little more, also see if I can verify I am truly getting a good 12V supply to cdi, with the plug in. I have the reverse and shift lever stuff all off just in case I need to take that left side cover off again. I still can't help but thinking about hitting that cover and suddenly having it work for awhile. Makes be feel like flywheel and timing aren't the issue, but the jarring did something.
 

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The switches are the same part number - both are normally open when in forward - they are the path to ground for each light

Yes, a good 12v is important - I believe 90% or more of the electrical problems I have dealt with are connection issues and 90% of those are grounding issues

Let me know where you get with this - I'm curious about the alarm unit being the cause of the problem.
 

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Discussion Starter #16
Just a quick update. Over the weekend, I took a bunch of parts over to my father in law to test on his 97-
3 cdi boxes all tested good
Reverse inhibitor tested good
Both spark plugs tested good
Both coils I took over tested good

By testing I mean I installed each component one at a time, and his quad started up and ran fine with each one. Just a recap- My keyswitch I unplugged and jumpered the wires- same issue. Unplugged the gray wire from the reverse switch- reverse light comes on and quad will not even turn over. The 97 I have access to, will not turn over at all in reverse, whether clutch pulled in or not.

Found a spot in the keyswitch wire that inslulation was cut and wire was a little corroded and few strands broken. Going to repair that tonight. Will also look at the killswitch a little closer, if I can get the button off, so I can get it out of the housing. Not sure my next step after that
 

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Discussion Starter #18
Sadly no, I repaired the frayed wire and it didn’t help at all. Going to try and bypass the kill switch still. Tried a different rectifier too and no help. Was going to measure output of the pulse generator, I am measuring for peak AC voltage and getting .7VAC. I think that is correct, but have to get back over and check the 97 and see. Was trying to fix my scopemeter to get a better look at that output, but the scopemeter repair is not going well
 

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With a std meter, you are not reading peak voltage, but average voltage the ignition system works on peak voltage.

The kill switch simply kills the 12v going to the CDI unit - if there is 12 volts on the black wire with the white stripe at the CDI unit and the CDI and coil work on the other machine, then the stator or pulse gen or both is the problem unless the flywheel key sheared and the rotor is out of time.

Keep me updated and I will try to help you get the thing going.
 

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Discussion Starter #20
Should have specified that I have a min/max recorder on my meter. I think you are correct though, I did replace both the pulse generator and stator, with supposed used working parts. Parts ohm out properly just as the old ones did, but I’m running out of things it could be. Def will be pulling the cover to check the flywheel. Don’t think the key was sheared but will see. Now one other thing, what about magnet in the flywheel being weak? I haven’t really seen anyone have that, but I have heard of it
 
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