Ohm Meter and Magnato
- Thread starter davearoy
- Start date
fall_down_stand_up
New Member
Every CDI and Magneto will have different reading's. And you want to check both CDI and Magneto several times.
In my opinion you want to have your reading's within 75-80% what is posted. This is just a reference, there is No exact readings. If your reading are not the same as posted, which they are most likely are not, go by the 75-80% within what we are reading.
Magneto
Use Low Ohm-Meter Scale About 200 Ohms
1) Check Ohms between BLACK wire and WHITE wire. Reading should be around 2 Ohms
2) Check ohms between BLUE wire and WHITE wire. Should be around 300-400 ohms.
CDI
Use Ohm Meter High Scale About 200-K
1) Positive lead on BLUE wire and Negative lead on BLACK wire should read infinite (no activity)
2) Positive lead on BLACK wire and Negative lead on BLUE wire. Should be about 130-150 K-ohms
3) Positive lead on Spark Plug wire and negative lead on BLUE wire. Should read between 135-155 K-ohms
Switch to Low Scale 20K
4) Measure between Spark Plug wire and and Black lead. Should be about 2.5 - 2.7 K- ohms
This will give you all the info you need....
John-John
In my opinion you want to have your reading's within 75-80% what is posted. This is just a reference, there is No exact readings. If your reading are not the same as posted, which they are most likely are not, go by the 75-80% within what we are reading.
Magneto
Use Low Ohm-Meter Scale About 200 Ohms
1) Check Ohms between BLACK wire and WHITE wire. Reading should be around 2 Ohms
2) Check ohms between BLUE wire and WHITE wire. Should be around 300-400 ohms.
CDI
Use Ohm Meter High Scale About 200-K
1) Positive lead on BLUE wire and Negative lead on BLACK wire should read infinite (no activity)
2) Positive lead on BLACK wire and Negative lead on BLUE wire. Should be about 130-150 K-ohms
3) Positive lead on Spark Plug wire and negative lead on BLUE wire. Should read between 135-155 K-ohms
Switch to Low Scale 20K
4) Measure between Spark Plug wire and and Black lead. Should be about 2.5 - 2.7 K- ohms
This will give you all the info you need....
John-John
freewheeling frank
New Member
i dont know what range your meter has but from what john said you will want to use multiple settings as you are looking at between (2) and275k ohms, frank
caraddict96
New Member
can anyone still help me on this subject???caraddict96
New Member
ok well i have a different problem than that. its not my magneto thats bad. my cdi gives the wrong readings and my bike wont start but i have fire, gas, compression, air. so i need to know if its my cdi. if anyone has knowledge on this please reply.
If your plug has fire then the CDI is probably ok. If there's also gas, compression, and air then timing is the only option. That is almost impossible on these engines though so I suspect one of these factors is not working as good as you think. How did you determine these are ok?
Did you try squirting gas directly into mouth of carb and trying to start down a big hill?
caraddict96
New Member
ive tried starting fluid down a big hill.
if i try to start it to much i also get a few drips of fuel outta the pipe.
i know there is gas bc the plug is wet after numerous times of trying to start it. compression is good bc the gaskets are sealed and the engine is hard to crank just as usual. and well i know that i have air bc otherwise fuel would not pull through the carb otherwise. and my timing should be good ask the groove the magnet goes on is not sheared.
idk i got a new cdi coming through warranty. should be here by friday. and if its not that next might be rings and gasket kit just to make sure the compression is certainly good.
does anyone know more specifically how to check the cdi. on the spark plug to black wire set at 20k ohms i get a reading of 5.3k-5.4k ohms. then on the spark plug to white set at 200k ohms i get about 5.2k-5.3 ohms.
if i try to start it to much i also get a few drips of fuel outta the pipe.
i know there is gas bc the plug is wet after numerous times of trying to start it. compression is good bc the gaskets are sealed and the engine is hard to crank just as usual. and well i know that i have air bc otherwise fuel would not pull through the carb otherwise. and my timing should be good ask the groove the magnet goes on is not sheared.
idk i got a new cdi coming through warranty. should be here by friday. and if its not that next might be rings and gasket kit just to make sure the compression is certainly good.
does anyone know more specifically how to check the cdi. on the spark plug to black wire set at 20k ohms i get a reading of 5.3k-5.4k ohms. then on the spark plug to white set at 200k ohms i get about 5.2k-5.3 ohms.
Creative Engineering
New Member
At some point, did you remove the magnet?
It "is" possible to install it backwards...the engine will not run if the magnet was installed backwards.
Jim
It "is" possible to install it backwards...the engine will not run if the magnet was installed backwards.
Jim
It may also be possible to install the coil backwards but this will distort the frame.
You said your plug had fire so it's unlikely the CDI is bad. They hardly ever fail compared to the magneto. Unfortunatley due to variations in meter circuits there is no reliable way to check CDIs.
How did you check for plug fire?
caraddict96
New Member
well it is on the same way as last time it ran and has never been removed.
thanks though
caraddict96
New Member
i checked it with my ngk spark plug attached to my accel wire, and i put an alligator wire clip on the edge of the spark plug whole and the other end on the side of the treads. o roll the bike at a fast walk and i have spark.
do u think i may have lost compression through the spark plug? i tighten it good but there is always oil residue on the treads.
If you have spark a new CDI probably won't help. Lost compression is obvious, at least it is on my 14,000 mile bike. You can tell easy because pushing the bike with and without the engine engaged makes no difference.
You CAN hear that piston turning over and feel resistance when you push it, right?
caraddict96
New Member
o yeah i can see it go up and down, newer motor 100 or less miles and new head. and i can not turn the wheel by hand when clutch is out. lots of resistance. but maybe not a enough. is there oil on ur spark plug treads?
Yes, my plug threads are oily but the electrode part should be dry before re-installing. Try another plug. They are cheap and very common cause of starting problems.
Junster
New Member
The 2 times I've had this happen was due to a flooded condition in the lower case. turn off the gas and remove the plug. Ride a little ways with the clutch out. Put the plug back in turn on the gas and try it with a dry plug. Another thing that can cause it is a plugged up stock exhaust pipe.
2manyprojects
New Member
did you ever resolve your issue? I have the EXACT same condition on my bike, and am pulling out my hair trying to solve it!
Norman
LORD VADER Moderator
you got fuel, spark, air.
you need the spark at the correct time.
a couple of things to try
gap the spark plug at 0.020 to 0.025" gap do this on a fresh clean new spark plug test the spark plug on the head again make sure you have spark before you try the spark plug in the engine.
if it won't pop or start.
remove the mag rotor there is a half moon key(wood ruff key) that is either missing or sheared if you are getting spark but its not firing up or even popping. mark the rotor before removing it so you can install it correctly they won't fire if put on backwards.
I hope you have the fuel mixed correctly at least 25 to 1 mixed in a fuel can and not in the bikes tank. if you mix the fuel in the bikes tank the oil can get in the carb first and that will fowl out the spark plug fast and for a long time. I still like the stock china spark plug for me they work good as any spark plug all spark plugs will go bad and if one gets dropped, throw it away.
also if you've flooded the engine you will need to purge the engine of fuel pedal the bike with the spark plug out and the cdi disconnected fuel turned off at the tank, throttle wide open and the choke in the off or down position pedal it with the clutch let out it shouldn't take much to clear the engine 50' should do it then try the engine.
you do have the white wire insulated and the wires to the ignition all good and tight plus insulated. kill switch wire up? or disconnected until you get it running?
your in still water is that in Ok.? I live 3 hrs west from Oklahoma city,Ok.
you need the spark at the correct time.
a couple of things to try
gap the spark plug at 0.020 to 0.025" gap do this on a fresh clean new spark plug test the spark plug on the head again make sure you have spark before you try the spark plug in the engine.
if it won't pop or start.
remove the mag rotor there is a half moon key(wood ruff key) that is either missing or sheared if you are getting spark but its not firing up or even popping. mark the rotor before removing it so you can install it correctly they won't fire if put on backwards.
I hope you have the fuel mixed correctly at least 25 to 1 mixed in a fuel can and not in the bikes tank. if you mix the fuel in the bikes tank the oil can get in the carb first and that will fowl out the spark plug fast and for a long time. I still like the stock china spark plug for me they work good as any spark plug all spark plugs will go bad and if one gets dropped, throw it away.
also if you've flooded the engine you will need to purge the engine of fuel pedal the bike with the spark plug out and the cdi disconnected fuel turned off at the tank, throttle wide open and the choke in the off or down position pedal it with the clutch let out it shouldn't take much to clear the engine 50' should do it then try the engine.
you do have the white wire insulated and the wires to the ignition all good and tight plus insulated. kill switch wire up? or disconnected until you get it running?
your in still water is that in Ok.? I live 3 hrs west from Oklahoma city,Ok.
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