'92 TRX300 Fourtrax no spark - Honda TRX Forum
 
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Old 12-20-2018, 01:48 AM Thread Starter
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'92 TRX300 Fourtrax no spark

Breaking out spark issues from on this bike from the transmission thread.


Last year this machine started having intermittent spark. It seemed temperature related... on super cold mornings there would be no spark. Other times it would start and run fine. After ruling out carb issues I noticed no spark. I immediately tried a new spark plug. No spark.


After reading nearly every "no spark" thread I could find, it seemed the easiest thing to start with was a replacement CDI. I really thought it was the CDI, and temperature or maybe humidity was causing microscopic shorts or something. The CDI I bought came with a new coil so I swapped out both. Still no spark.


I unhooked the pickup coil and stator and ran resistance and continuity checks and they were within spec. I found a post mentioning a stator that tested good, but when inspected it had burnt wiring and was actually bad. I pulled the stator cover and inspected the stator. It visually looked fine, and I retested and it looked fine. As long as I had the stator cover off I decided to replace the pickup coil as they are fairly cheap and I know they start to fail around this age anyway.



Still no spark. I retested the CDI wiring via the manuals CDI trouble shooting section (including picture of the tests and expected values I used). One thing I noticed is the shop manual wiring mentions a Y/W wire which I do not have. I am including a picture of the wiring on this machine.


My values on CDI wiring are:


BL/Y and G: .2 ohms
Bu/Y and G: 340 ohms
Bl/W and G: 12.7 volts
Gr and G: No continuity
Y/W and G: I dont have Y/W wire
YW and Y: I dont have Y/W wire.


I got a 2nd CDI on the chance of the first one being bad, still no spark. I cant imagine both new CDI are bad along with the OEM.



IDK where to go from here, what to test next.





-DallanC
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Old 12-20-2018, 04:43 PM Thread Starter
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I'm still curious about the manual referencing a Y/W wire to the CDI when my wiring harness doesn't have it. That then is a test I am unable to make.

But, with that on the back burner I've ordered a new voltage rectifier as its one of the few parts at this point that hasn't been replaced.


-DallanC
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Old 12-20-2018, 04:57 PM Thread Starter
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Oh and I don't know how meaningful it is, but I do see the single spark from the CDI false trigger.


-DallanC
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Old 12-20-2018, 10:56 PM
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Dallan - although it tests good, you probably need to replace the stator

A friend of mine lost spark on his 84 XR200 4-valve

He used my meter and service manual to test the ignition system - the only thing that tested good was the stator, so he replaced the coil (cheap and easy to get to); no spark - he changed the CDI box, (not exacly cheap, but easy to change) ; no spark - the next thing which was inside the engine on the clutch side was the pulse generator (not easy to get to, but cheaper than the stator); still no spark - finally he installed a new stator; BINGO, spark - it started and ran!

Later he put the old CDI box back on and still had spark, he then put the old CDI box back on, it still ran - he never did put the old pulse generator back on, but he was pretty certain it was good too.

Turned out the only part that tested good was bad. Today I have a peak voltage tester and can more accurately troubleshoot ignition systems.

As to the Yellow/white wire - just presume the yellow wire is the y/w and test under that presumption - I studied the wiring diagram and the yellow/white wire is Siamese'ed to one yellow wire from the stator - if you use the lowest ohm scale your meter has and check to all three of the yellow wires from the stator, the resistance should near zero on one leg and you will read winding resistance on the other two legs.
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Old 12-20-2018, 11:59 PM Thread Starter
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Quote:
Originally Posted by Here 2 help View Post
Dallan - although it tests good, you probably need to replace the stator

A friend of mine lost spark on his 84 XR200 4-valve

Awesome bikes, I had the 85 XR200R 4 Valve. Light weight, lots of torque for fun tight trail riding. I sold it, and found a mint condition 1996 XR250L (the factory road legal XR to get across town to the hills without a trailer). First 3 gears are lower like the XRs, top 3 are higher like the XLs). Love it, perfectly balanced bike. I put lower geared sprockets on it as my house is at 4500ft and the mountains right behind me are 10k ft, need that torque!


Quote:
He used my meter and service manual to test the ignition system - the only thing that tested good was the stator, so he replaced the coil (cheap and easy to get to); no spark - he changed the CDI box, (not exacly cheap, but easy to change) ; no spark - the next thing which was inside the engine on the clutch side was the pulse generator (not easy to get to, but cheaper than the stator); still no spark - finally he installed a new stator; BINGO, spark - it started and ran!

Later he put the old CDI box back on and still had spark, he then put the old CDI box back on, it still ran - he never did put the old pulse generator back on, but he was pretty certain it was good too.

Turned out the only part that tested good was bad. Today I have a peak voltage tester and can more accurately troubleshoot ignition systems.
Yea I found that post here where you mentioned it, I hoped it was fine... it tests A-OK on the meter, continuity in the right range across the 3 yellow leads, and zero continuity between them and ground... but really its the last thing I haven't replaced.



Soooooo I just ordered one up. I'm far from a rich guy but dropping $100 or so on new parts to get this bike going is well worth it I guess. Other than dropping that valve and having a dealer rebuild it, its been a reliable machine. My stator is the 12 pole version. I'll replace the rectifier as well anyway... and if I still dont have spark I'll roll it outside and light it on fire.



Quote:
As to the Yellow/white wire - just presume the yellow wire is the y/w and test under that presumption - I studied the wiring diagram and the yellow/white wire is Siamese'ed to one yellow wire from the stator - if you use the lowest ohm scale your meter has and check to all three of the yellow wires from the stator, the resistance should near zero on one leg and you will read winding resistance on the other two legs.
Gotcha.



Well I'll post an update after Christmas when the parts get here. At least I haven't put oil in it yet from having the stator cover off.


Thanks again for the tips and suggestions.




-DallanC
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Old 12-29-2018, 08:32 PM Thread Starter
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Parts arrived and I finally got time to work on this again.

R&R voltage regulator: No spark.
R&R Stator: No spark.
R&R pickup coil (for the second time, new stator came with another one): No spark

/sigh

I feel like I'm throwing money to the wind at this point.

So to recap: New CDI, New Coil, New Stator, New Pickup Coil, New Regulator. Atm, all wires at the CDI pass shop manual specs.

Back to square one. I'm going to read through the manual again. Whats the easiest way to bypass the wiring harness and see if the harness is the issue?

If the kill switch on the handlebars is flipped / failed, what wire to the CDI does it affect?


-DallanC

Last edited by DallanC; 12-29-2018 at 08:37 PM.
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Old 12-29-2018, 09:33 PM
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Unfortunately, there's no easy way to bypass the wiring harness.

First step is to verify the wires in the wiring harness have continuity from end to end - next verify there is 12 volts on the blue/white and gray wires at the CDI unit - here's a tricky part; the kill switch on the handle bar is fed 12 volts on the black wire - when the switch in in the run position, the black/white wire is hot - now the black/white wire becomes blue/white somewhere between the handlebar switch and the CDI unit. If you check for 12 volts on the blue/white wire at the CDI unit, all you have to do to check the handlebar switch is turn it off and on - the 12 volts should be there in the on position and gone in the off position.

The dark green wire at the CDI unit should have continuity to ground - the yellow/white wire should have continuity to all three yellow wires from the stator - the blue/yellow wire should have continuity to ground through the pulse gen - the blue/yellow wire should have continuity from the CDI unit to the ignition coil.

Let me know if this helps or if you have already done all this.
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Old 12-30-2018, 09:59 PM Thread Starter
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Quote:
Originally Posted by Here 2 help View Post
First step is to verify the wires in the wiring harness have continuity from end to end
Not completed all of this yet.

Quote:
- next verify there is 12 volts on the blue/white and gray wires at the CDI unit - here's a tricky part; the kill switch on the handle bar is fed 12 volts on the black wire - when the switch in in the run position, the black/white wire is hot - now the black/white wire becomes blue/white somewhere between the handlebar switch and the CDI unit. If you check for 12 volts on the blue/white wire at the CDI unit, all you have to do to check the handlebar switch is turn it off and on - the 12 volts should be there in the on position and gone in the off position.
Confirmed. 12v on the grey wire at the CDI, 12v on the black/white wire at the CDI. Flipping the kill switch either way removes current. That effectively eliminates the kill switch as an issue.

Quote:
The dark green wire at the CDI unit should have continuity to ground
Confirmed.

Quote:
- the yellow/white wire should have continuity to all three yellow wires from the stator
Ok this might be the problem: But I need clarification here, I might be testing this wrong.

If I run my red test lead from yellow on the CDI plug, and the black lead grounded to engine I get no continuity. If I unplug the Stator and run my black lead through each of the 3 stator wires via the 3 pole stator plug, I get continuity (with red lead still connected to yellow on CDI plug).

That would indicate a fault along yellow, which runs through the regulator if I'm not mistaken correct? Then from regulator down to the stator? When I R&R'd the regulator, the plug was pretty corroded. I tried to clean it up a bit but maybe its still faulting there.

Quote:
the blue/yellow wire should have continuity to ground through the pulse gen - the blue/yellow wire should have continuity from the CDI unit to the ignition coil.
blue / yellow has 375ohms from the CDI plug to.... well where ever its grounding.



Ignition coil has black/white strip and a green. Green has continuity to ground.


-DallanC
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Old 12-31-2018, 01:59 PM
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Quote:
Confirmed. 12v on the grey wire at the CDI, 12v on the black/white wire at the CDI. Flipping the kill switch either way removes current. That effectively eliminates the kill switch as an issue.
Agreed - switches are working

Quote:
If I run my red test lead from yellow on the CDI plug, and the black lead grounded to engine I get no continuity. If I unplug the Stator and run my black lead through each of the 3 stator wires via the 3 pole stator plug, I get continuity (with red lead still connected to yellow on CDI plug).
That is correct - the yellow lead at the CDI is connected to one leg of the alternator - the lead it is connected to will have a lower resistance than the other two leads, but as long as no continuity to ground is good.

Quote:
That would indicate a fault along yellow, which runs through the regulator if I'm not mistaken correct? Then from regulator down to the stator? When I R&R'd the regulator, the plug was pretty corroded. I tried to clean it up a bit but maybe its still faulting there.
No - it does not run 'through' the regulator, but to it. The corroded plug can be cleaned by soaking it in white vinegar (acetic acid) - after cleaning, fill with dielectric grease before reconnecting - the grease will exclude air and moisture preventing future corrosion.

Quote:
the blue/yellow wire should have continuity to ground through the pulse gen - the blue/yellow wire should have continuity from the CDI unit to the ignition coil.
blue / yellow has 375ohms from the CDI plug to.... well where ever its grounding.

That is good

[qoute]Ignition coil has black/white strip and a green. Green has continuity to ground.[/quote]

Coil should have black/yellow and green wires (by the wiring diagram) - check the continuity of the b/y wire at the CDI box to the b/w wire at the coil - it should have continuity

Last edited by Here 2 help; 12-31-2018 at 02:02 PM.
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Old 12-31-2018, 04:15 PM Thread Starter
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Ok using this diagram (its better resolution than my shop manual PDF), there should be continuity from the Y/W at the CDI and ground, through it looks like Y/W on the pulsar plug. As we've discussed, I dont have Y/W at the CDI so I'm testing on Y.


ATM I do not have continuity, this seems to be the issue. I will look into this deeper, later today.



I will also clean the regulator plug but as you correctly stated, and the diagram shows, Y/W on CDI and Y on stator don't pass through the regulator. I was mistaken on where Y/W ties into the stator leg.



PS: Happy new years everyone!




-DallanC
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