help 85 trx 125 no spark
#1
#2
help 85 trx 125 no spark
I would have thought an 85 would have points, and not cdi, but i could be wrong.If it has points, they could be out of adjustment, or fried.
There has to be a battery, with some voltage, in the circuit for there to be spark. And there has to be a battery,hooked up, for the lights to try and light while pull starting...thats the alternator, providing juice.
Im sure this has a battery /coil ignition system, and not a magneto, so a battery is necessary for spark.
If you get a battery hooked up, and there still isnt spark, then it sure could be the cdi.
Also check the kill switch circuit
There has to be a battery, with some voltage, in the circuit for there to be spark. And there has to be a battery,hooked up, for the lights to try and light while pull starting...thats the alternator, providing juice.
Im sure this has a battery /coil ignition system, and not a magneto, so a battery is necessary for spark.
If you get a battery hooked up, and there still isnt spark, then it sure could be the cdi.
Also check the kill switch circuit
#3
help 85 trx 125 no spark
No Hondabuster, it's a magneto CDI. A battery isn't necessary for spark. To answer your light question, Alpine, it may light the lights IF they're on, and their good, and you pull it hard enough. It seems those little guys were prone to burning out bulbs if they didn't have a good battery in them. But I can tell you that stator plate has separate lighting and ignition generating coils, so looking at your lights to trouble shoot the spark doesn't tell you much.
#4
help 85 trx 125 no spark
ok i was just thinking that the lights shoulld try to come on when ya pull start it i think they did but anyhow im trying to find out if the alternator behind the pull start case is the problem not letting me get any spark.there is 2 yellow wires and a black with red stripe comeing out of the case i guess thats the alt or stator? the book shows alot of copper wire wrapped in circles so i hooked up a meter to the yellow wires and it read 15 volts dc .which i thought was okay .and for the black wire with red stripe there was no reading.so im confused still..someone told me to hook up the black wire to the red on the test meter and the black to the bike ground and pull it and i should get at least 100 volts ac. i wish someone had a bike like mine so i could see what happens when they do that okay im off to the basement to try it thanks alot...
#5
help 85 trx 125 no spark
The black\red is the ignition generating coil wire and the one you want to be concerned with. Unplug it, turn your meter to ohms, and check resistance between the harness wire coming out of the engine and ground. You should see somewhere between 100 and 400 ohms. If it is open or has a very low resistance, like .2 ohms, the stator is faulty. If it passes this test, turn your voltmeter to VAC and probe from the black\red wire to ground, engine side of the harness, (polarity makes no difference) and pull the engine over vigorously. You should see from 15 to 25 VAC, depending on how fast the engine is turned over. If you see very low or no VAC, the stator is faulty. From your post it sounds like the stator is bad, but you didn't say if you had the harness unplugged when you tested. Make sure to unplug it.
#6
#7
help 85 trx 125 no spark
ok well i unpluged the black red wire from motor and probed it and grd the other to bike and got 40 volts ac so i guess this is a good thing.. now does this mean that its getting pwr to cdi but not coming out to coil? i think i should chk the wire going to the cdi i have the charts on it and if so that means the cdi box is not letting it thre right? any other tests i could do? thanks again
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#8
help 85 trx 125 no spark
You have to eliminate ALL other possibilities, then the problem MIGHT be the CDI unit. If you see a chart telling you to do a series of tests on the CDI directly, ignore it, they don't work, Honda has acknowledged this in later versions of shop manuals. I usually unplug the CDI and do all tests directly at the harness side of the CDI coupler. Nb makes a good point, it could be something as simple as a faulty kill switch. There should be 5 or 6 wires going to that coupler. Please tell me the wire colors and I will tell you the tests.
#9
#10
help 85 trx 125 no spark
OK alpine 8181, here goes. Black\red - exciter coil , black\white - kill switch , green - ground , yellow\blue - pulse generator , black\yellow - ign coil primary circuit , grey - reverse sender
green to chassis ground - should be a closed circuit
black\red to green - 100 - 400ohms
black\white to green (switches in run position) - should be open circuit
black\white to green (either switch in off position) - should be closed circuit
blue\yellow to green - 50 to 300 ohms
black\yellow to green - around .4 to 4.0 ohms
grey should have battery voltage with the key on and put in reverse, no voltage in any other gear
spark plug wire to ground - 10 -20 Kohms
If all that tests good, next step would be to remove the cam cover, upper left engine (two fasteners). Look for any grinding or touching on the pulse generator pickup and rotor coil (bolted on cam), next check for air gap between pulse generator and rotor coil, should be about .014 inches. If all that checks out, try a known good CDI unit. Good luck.
green to chassis ground - should be a closed circuit
black\red to green - 100 - 400ohms
black\white to green (switches in run position) - should be open circuit
black\white to green (either switch in off position) - should be closed circuit
blue\yellow to green - 50 to 300 ohms
black\yellow to green - around .4 to 4.0 ohms
grey should have battery voltage with the key on and put in reverse, no voltage in any other gear
spark plug wire to ground - 10 -20 Kohms
If all that tests good, next step would be to remove the cam cover, upper left engine (two fasteners). Look for any grinding or touching on the pulse generator pickup and rotor coil (bolted on cam), next check for air gap between pulse generator and rotor coil, should be about .014 inches. If all that checks out, try a known good CDI unit. Good luck.