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So the switch repair seemed to go ok. Got the crankcase put back together and on the bike and the starter motor turns the engine when I'm in neutral and it almost tries to start, especially if I hold in the throttle, but it just won't fire. So I checked the ignition coil and the wire connection between the coil wire and the cap seemed iffy. The cap pulled right off the coil wire without effort. I put it back on, pulled the plug and tested for spark. Can smell gas. I should mention bike ran just fine before taking off the crank case cover. Spark is almost not there at all, every so often some weak spark will jump. I pulled the coil out, tested resistance and the coil itself seems ok and in range but the cap has complete resistance until I set my multimeter to the 200M setting. So I'm thinking the cap is bad. New OEM coil came today but still waiting for new OEM cap. I did find on Amazon a cheap coil and it arrived yesterday. https://www.amazon.com/gp/product/B00YWM52S2/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 I tested it and the resistnace was a bit lower than the rang at 2.5 Ohms from green to cap. The cap seems to not fit well on the top of the NKG DR8ES-L spark plug threaded top. So I picked up a Champion 809 RASHC thinking that would fit the cap better, but the top stud was too thick for the cap to fit it. So no joy yet. I have checked the pulse generator resistance and that seems to be within speck. The bike is old and bolts are rusty, not easy to get the front fenders off without busting that all up so I haven't checked the CDI yet. I keep going back to what I have touched. The bike sounds to me like the timing is just a bit off, but according to the workshop manual there is no way to adjust the timing and it is all controlled by the CDI. When I took the crank case cover off I got a bit ahead of myself and made an attempt to undue the crankshaft bolt. All I succeeded in doing was rotate the crank a few times before I came to my senses that was completely unnecessary. Is it at all possible that in hand cranking the motor like that I got it off of it's timing and if so, is there a way to get it back? Seem like there is no way to even check the timing via the inspection port unless the motor is running at idle Do it need to get it set to TDC before doing some part of the cover replacement? It didn't seem to me like it should have mattered at all, but now I'm second guessing myself on it. I'm still hoping I just need the OEM plug cap with the new OEM coil and it will fire right up, but while I wait, I might as well reach out.

Many Thanks!
 

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Well, if you didn't have the cam out when the engine was turned, it would not change the timing and the spark timing is set by the crankshaft/flywheel, so the timing cant be changed without moving the flywheel on the crankshaft.

The spark plug cap has a 5000 ohm resistor built into it - measure just he cap and it should be close to that - a tight fit on the plug is not required - you will actually get a stronger spark with a loose cap, but the cap may come off the plug when thrashing the machine which would be irritating. The cap is a tight fit simply to assure it does not come off while riding.
 

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Well, if you didn't have the cam out when the engine was turned, it would not change the timing and the spark timing is set by the crankshaft/flywheel, so the timing cant be changed without moving the flywheel on the crankshaft.

The spark plug cap has a 5000 ohm resistor built into it - measure just he cap and it should be close to that - a tight fit on the plug is not required - you will actually get a stronger spark with a loose cap, but the cap may come off the plug when thrashing the machine which would be irritating. The cap is a tight fit simply to assure it does not come off while riding.
Thanks for the confirm that the timing shouldn't have shifted. It's possible that I'm not using my meter right, but I don't get a reading at all on just the cap unless I set the dial up to 200M and then it is all over the place from 8.5M to 15M. I just get a 1 at 200, 2k and 200k settings. The wire itself reads 3.0K fine at 200K setting. I really don't know how the cap itself could have gone bad. I can see the connection to the wire getting messed up, but I guess I don't know what would make the cap itself fail from just doing nothing. Still waiting for the new cap. It was supposed to have shipped friday, but now partzila is saying it won't ship till the 23'rd. Very annoyed. Yet from what your saying, the coil I got off amazon where the fit is a bit loose should be fine and I did see some spark, just not good consistent spark.

I also suspect I may not have properly tested the pulse generator as that was out and being kicked around with the sator for a bit. Could being in physical contact with the magnets on the sator some how mess up the pulse?

Other shot in the dark... The black wire on the rectifier was broken and I used a crimp connect to reconnect it before I started tested after repairing the neutral switch. Is there any way that disconnecting that black wire might be some sort of hack around a failing CDI unit. I'd hate to undue that fix just to test this theory out.

Thanks again!
 

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Here's the ignition system:
4317

One thing at a time:
The CDI does not needs voltage to create a spark.
The alternator supplies AC voltage to the CDI unit to charge the capacitor and the pulse coil tells it when to fire.
The spark is killed when the black/white wire is connected to ground.
Battery voltage is supplied to the unit via the white wire - this is just to let the unit know if it's in neutral or reverse.
In neutral, the starter motor will run when the button is pressed.
In reverse the voltage is decreased and the unit limits RPM to a preset value.

You can't determine much from a multi-meter or ohm meter - you need a peak voltage tester to troubleshoot.
If you have spark on every stroke regardless of the strength of the spark, the pulse coil is doing it's job.
To diagnose a weak spark, you first need a new spark plug.
Assure the plug cap has around 5K resistance - if that's good you need to check the peak voltage output of things.
The pulse coil is typically 3 to 5 volts peak (a peak meter converts AC to DC and displays on the DC scale)
The charging coil of the alternator is about 35 to 45 volts at cranking speed (higher at higher RPM)
The output from the CDI to the coil is about 100v
The output from the coil to the spark plug is about 30 to 40,000 volts

Let me know if this helps. I can send you a PDF of the service manual if you need it.
 

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Here's the ignition system:
View attachment 4317
One thing at a time:
The CDI does not needs voltage to create a spark.
The alternator supplies AC voltage to the CDI unit to charge the capacitor and the pulse coil tells it when to fire.
The spark is killed when the black/white wire is connected to ground.
Battery voltage is supplied to the unit via the white wire - this is just to let the unit know if it's in neutral or reverse.
In neutral, the starter motor will run when the button is pressed.
In reverse the voltage is decreased and the unit limits RPM to a preset value.

You can't determine much from a multi-meter or ohm meter - you need a peak voltage tester to troubleshoot.
If you have spark on every stroke regardless of the strength of the spark, the pulse coil is doing it's job.
To diagnose a weak spark, you first need a new spark plug.
Assure the plug cap has around 5K resistance - if that's good you need to check the peak voltage output of things.
The pulse coil is typically 3 to 5 volts peak (a peak meter converts AC to DC and displays on the DC scale)
The charging coil of the alternator is about 35 to 45 volts at cranking speed (higher at higher RPM)
The output from the CDI to the coil is about 100v
The output from the coil to the spark plug is about 30 to 40,000 volts

Let me know if this helps. I can send you a PDF of the service manual if you need it.
This is all very helpful. I actually have the shop manual with this diagram, Just not the knowledge and experience to fully understand how the circuits operate. Your explanation is great! I'll see about getting my hand on a peak voltage tester. I don't think I'm getting spark on every stroke, but I also don't think holding the plug out of the engine and trying to touch the barrel to the engine is the best test method either. I can can some spark, but it's not at all consistent. I'm wondering if I might have a short in the harness that goes down into the crankcase from you comment on the black/white wire touching ground. I'm traveling now, so will be a number of days before I'm back at this. But again, very grateful for the assistance.

Chears!
 

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Here2Help, one other thought occurred to me while driving around. Maybe I messed up the switch. Can you tell me if the red rev light should go out when switched in to neutral? Mine stays on, so I now have both the red rev and the green nut light active at the same time. You said CDI will reduce voltage when in Rev.. this might make it hard to start me thinks and explain the symptoms. When I was looking at the physical aspects of the switch, I was testing the connectivity out of the case. The lower spring would normal make contact with ground by scraping the bottom of the case. I got it into my head that the top of the spring contact needed to touch the ramp and the nub touched the neutral contact spot at the same time to close the circuit and give connectivity to the green wire.. but now I'm thinking those should not be touching at the same time and when in the case the green wire will connect to ground when the bottom of the spring is touching the case. Does this sound like I'm onto something?
 

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By Jove, I think you've got it.

The design is the nub on the shift drum contacts the neutral contact when in neutral and the nub contacts the other when in reverse - no connection between them - when in reverse the battery positive is connected to ground via the switch, but the current has to flow through the resistor which lowers the voltage. The resistor is in actuality the reverse light bulb filament.

Try to get it fixed so the reverse light is on only when in reverse and neutral is on only when in neutral and I think you will have solved the problem. A work around would be to disconnect the reverse light and if the neutral light does not work properly simply ground the wire. With the reverse light disconnected one of two things will happen; it will die when put in reverse or it will not limit engine speed in reverse. If the neutral light works properly the no worry - if the neutral light does not come on, you can't engage the starter motor - if you wire the neutral wire to ground so the light is on all the time, I believe it will start (or try to) when in gear.
 

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Bingo, I think that will be it. It just doesn't make sense that other things went south while I had the case off and oil out and I know I intentionally allowed for the rev and neutral to be touching the way I shaped that ramp under a mis understanding on how it worked. I can pull that off and should be able to get that case off again to alter the ramp profile. I'll let you know in a week or so how I made out. Cheers!!!!
 

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Now I'm getting frustrated. I drained the oil, Pulled the crankcase cover back out and took it all apart again. reworked the switch so that when I had my black clip on the screw mount and the red clip on either the green or the white they would signal connectivity when the nub was on the respective contacts and it seem like if I moved from the green to the white or other way while on the same contact spot that there was no cross connection. So it seems ok, but the shaft is developing more play in the top plastic mount. But It seemed ok, so I put it all back together again and fill up the oil (using the last gasket I had on hand) and no no joy. I get Rev light in reverse only, but no Green light and no conductivity when in neutral on green wire. The red rev sometimes will stay on when I come up from rev. It goes off if I go into first and come back down to neutral again. So it's just not right still inside and I bet the play is effecting how it all aligned up when fully installed. Very frustrating that I just can't buy a good part and slap it in. Guess I'll have to get some more gaskets and give it another go when I can. If someone reads this and knows of a place that might have old new stock, please LMK.
 

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I actually fround one on Ebay by searching for Sators. It was off of a purported running 86, both the sator and the switch and harness and only had the 2 wires connected to the switch rather than the 3 on the 91, but since 2 of those connections run in parallel I only needed to connect both the white and the gray from the pink connect plug to the swith gray rev wire. Switch itself was the same and perfect fit. Totally did the trick. Once in, neutral and rev light worked as expected and my pre oil fill test to start it, the motor turned right over and started running with no effort. Very happy to have it working again and thanks go to everyone here for all the help!
4353
 

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Great news and information too that the parts swap and are compatible. Congratulations and thank you for closing this thread.
 
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