1986 TRX 350d. no spark - Honda ATV Forum
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post #1 of 21 (permalink) Old 04-20-2017, 07:40 PM Thread Starter
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1986 TRX 350d. no spark

Hello everybody! Bought this bike project 15 years ago and need some advice from all you experts! Installed new starter and battery and it cranked right over. Green neutral light comes on but red oil temp light doesn't. Engine sounds good/normal as it rolls over and has 135lbs compression. Checked the ignition coil and it shows .3 ohms resistance on the primary coil and 8.58 k ohms on secondary coil. Neither of the wires leading to the ignition coil have power when the engine is cranking. I have the Honda manual and both of those numbers are out of spec high. If the ign coil had power going to it a new one should be the answer but I think its worse than that. Manual says test CDI with a CDI tester. Only have multimeter and not very skilled with that. Any help will be greatly appreciated!
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post #2 of 21 (permalink) Old 04-20-2017, 08:14 PM
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1986 has a battery/CDI ignition and requires a fully charged battery to produce spark, so keep that in mind as you work on it.

Did you check the kill switch on the handlebar? Also snoop around the fuel cutoff relay and make sure the CDI is sending a voltage to that while cranking. Does the fuel pump run?

Compression is low at 135 lbs... assuming you are testing with a known accurate gauge and the throttle is being held wide open while cranking with the starter. Should be nearer to 200 lbs....

Last edited by retro; 04-20-2017 at 08:17 PM.
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post #3 of 21 (permalink) Old 04-20-2017, 09:31 PM Thread Starter
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Hey Thanks Retro. I'll check those things tomorrow. The battery is good. A year old out of my Rincon and I have a battery tender hooked up to it. As to the compression, the tester I normally use (cars) did not have the adapter for the smaller atv plug so I used the old one with a rubber end you jam into the head. rubber hard so I think its probably higher than 135 but I doubt its 200. Manual said 135 so I thought it was okay. Bike hasn't run for 20 years at least. It appears to be fairly low mileage. original tires with 30%-40% tread, shifter rubber like new, frame and skid plates pristine. I plan on converting it to propane so I need good compression. Thank-you for your help.
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post #4 of 21 (permalink) Old 04-20-2017, 10:27 PM
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Ya ok, been sitting a long time so probably be a good idea to put some oil in the cylinder if you haven't already. I'd go through it and unplug and plug back in every wire harness plug on it in case any are corroding. Also check every ground cable/wire for clean grounds. Got any pics of the purdy girl you can share..?
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post #5 of 21 (permalink) Old 04-22-2017, 05:22 PM Thread Starter
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Thanks Retro for your help. I have 11v going to bl/br wire on pump relay when cranking. took stop/light switch apart. have continuity between g wire and bl/white wires of stop switch. made the lights start working. still no power to ign coil.
compression is only 135psi. Started pulling plugs and checking grounds. looks good so far. Bike sat outside for 8 or9 years before I bought it (15 yrs ago) missing starter. I've rebuilt/fixed 30-35 bikes since (mechanical stuff-not electrical!) I retired last year, working my way thru projects. I've got 600 in it, willing to put 1000 in it, but tires are 400 and Wiesco piston kit is 150. I've learned not to just start replacing electrical items to find problem. moneypit! But I'm a beginner on electrical stuff. I have a Fluke 117 but had to read manual to get info for you. So you're dealing with an idiot! lol I'd like to use this bike as a workhorse. seems built for it. I have converted 20-25 small engines (6-28 hp) to run on LP and they just run so much better, no carb issues, fuel is $1 a gallon and enters engine as a vapor so no diluting oil should help wetclutches. Fuel pump does not run while cranking, but I won't need it. Probably run it gravity feed to check operation of transmission, but everything (driveline) moves freely by hand now. I just need spark! Appreciate your time and expertise.
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post #6 of 21 (permalink) Old 04-22-2017, 10:29 PM
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Hi Boppyguy,

Alright, this all looks pretty simple in the manual. I thought the 1986 350s had a battery ignition (DC-CDI) but the manual shows otherwise. So, if the manual is correct then the battery is used only for cranking the motor and to operate the fuel pump while starting. Spark is independently produced.

Click the image to open in full size.

So going by the above diagram the ignition switch should be checked for continuity between the Bl/W & G wires at the switch plug connector. You already have the neutral light working correct? I would unplug the CDI connector and make sure that looks clean and free of corrosion along with the alternator/pulse generator connector coming from the left side cover of the motor. Once all connectors are verified to be good and the engine ground cables (there are two of them, one negative battery cable and one system ground coming out of the wiring harness near/forward of the fuel tank?) verified good and clean it'll be time to test the pulse generator and stator exciter coil. While you are snooping around the above I'll need to study this system a bit more because it looks a bit incomplete to me. Let us know what you find...
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post #7 of 21 (permalink) Old 04-22-2017, 10:39 PM
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Also, after verifying Ign switch, kill switch, neutral light operation, all connectors and ground... with everything hooked up try tapping on the CDI box while the motor is cranking over and see if it produces spark at the spark plug while it is out and laying against the head, even momentarily.

Edit:
Also look at the CDI connector pins (inside the CDI connector plug) for a pushed in pin that may not be making good contact with the harness plug.

Last edited by retro; 04-22-2017 at 10:42 PM.
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post #8 of 21 (permalink) Old 04-23-2017, 01:31 AM
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Quote:
I have 11v going to bl/br wire on pump relay when cranking. took stop/light switch apart. have continuity between g wire and bl/white wires of stop switch. made the lights start working. still no power to ign coil.
According to the manual there should be NO continuity between the Bl/W and G/W (G?) wires from the ignition switch AND from the kill switch, with the ignition on. Continuity in either one of those shuts down the ignition.

Attached are the switches continuity, ignition components resistance, fuel cut relay continuity and voltage tests along with the system wiring diagram.
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post #9 of 21 (permalink) Old 04-23-2017, 06:20 PM Thread Starter
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WOW! okay thanks Retro. Alot of info to digest. I have the Honda Service Manual for the 86. I'll check it all out and let you know what I find. I saw your post on the 87! congrats on that. Has anybody out there ever used a Power Probe? Thanks again for your help Retro.
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post #10 of 21 (permalink) Old 04-23-2017, 07:01 PM
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I would check the pulse generator.
It has to first produce pulses to the CDI when the engine is cranking. Resistance is listed in the ign troubleshooting section, probably 300 -360 ohms for a 86.

Let us know what the resistance of the pulse generator is? Don't try to read the pulses just yet with a DMM they are spikes and might damage the meter internally.
The pulses then after they leave the pulse generator come out of the CDI when the engine is cranking and go to the ign coil and the fuel relay if all is ok in and around the CDI. The pulses on the + post of the ign coil trigger the coil for spark. Check for spark with the spark plug removed from engine head and
grounded real good to the engine. Don't let it just flop around not grounded good when looking for spark.

The pulses are the heartbeat of the system at first.

Last edited by Okie; 04-23-2017 at 07:06 PM.
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