[Lagorasfort]

Hi,
so I just bought a three wheeler basically because I wanted to put around the yard. Needless to say it won't start. I have run into serious issues even gathering data. The frame has no serial number that I can see. The bike is stripped down to the bare minimum. So if anybody that can help reads this, I would be grateful.
The guy that sold it to me said the motor was "a 1988 250"
It is a pull start.
There is no spark.
The wiring was a ball of wire and duct tape, so I cut it out to a component level.

Coil- there was one wire going to the coil. I read the coil and got .8 ohm from the primary to the core (ground), 4.11 kohm from the secondary (plug boot) to the core, 4.11 kohm from the primary to the secondary

CDI unit- There appears to have been 6 wires originally but I could only find 5, and one of the five was only stuck into the connector (no pin) * visual inspection of the CDI showed only 5 spades for a connector (the missing spade matched the wire with no pin. Where the wire was completly missing from the connector it appears the wire corroded (green dust)

Coming from the left side of the motor there are three wires. All the drawings I can find on the web show four wires. I have a general drawing that calls it "pulse generator", but there are only two wires to that. Is the third wire possibly the exciter coil or neutral switch?

So: Can I verify the CDI with a meter?
Does the readings of the coil indicate that it is good? I think so.
As there is no ignition or engine stop switch I don't see the need for it coming out of the CDI. Is that correct? I can just choke it out if I ever get it running.
If someone thinks they can help I can e-mail pictures.
If your reply is just sarcasm please be original.

 

[TRX2fiveO]

CDI WIring testing is.....black/yellow and ground------0.1-.02 ohm (ignition switch)
blue/yellow and ground -----290-360k ohm (pulse gen.)
reverse switch ----> gray and ground---- no continuity with reverse selector lever up
continuity with reverse lever down
Ground line----------> green/white and ground------continuity
That was the 4 pin connector
_________________________________________
The 2 pin connector is as follows
alternator exciter------> black/red and ground 100-300ohm
Ignition switch line----->black/white and ground-----no continuity w/switch on
continuity with the switch on
coil resistance between terminals is......0.1-0.2 ohm
resistance between green terminalwire and plug cap is 8.8-14k ohm

Be sure to disconnect the CDI connector first. the pulse generator is for the lights.
Also the AC regulator...disconnect and measure resistance between the two terminals of the harness side0.1-1.0ohms.
I hope this will help you out if you need anymore help let me or anyone else know we b glad to help you out.good luck

 

[Jbacon]

Well all I can say is good luck. Oh and welcome to the forum! Thats it for me to you. I have no clue what you just said about all those wires and stuff man. lol

 

[Lagorasfort]

Thanks, I will measure tomorrow when I go back to it.

 

[tomgodd]

Welcome to the FORUMS! I have never messed with all that electrical but I know a manual will help you.

 

[TRX2fiveO]

Piece of cake you can do it. but manuals are good to have lying around

 

[Saber6]

Welcome to the forums!!!!

 

[jeeping1974]

welcome to the forum.

A wiring diagram helps out a great deal with these kinds of problems.

 

[Lagorasfort]

Hey guys/Moose

First thanks for the replies. I think moose may have some idea of what I am trying to say, but not to the full extent. This is a three wheeler that I doubt could even be used for parts. Oddly enough my interest is bringing it back to life, so I can kill it again. There are no fancy options such as ignition switch, engine stop switch, lights, secured seat, etc. What I do have is the motor, coil, CDI unit. I agree a wiring diagram would help in this case, but I refuse to spend more on a manual than what the bike is worth.

What is the minimum requirement to get a spark?
Does the spark come from the "exciter coil" ?

Moose, thanks for your support. I measured the CDI unit but the color codes do not match up because I think that the unit I have is for a very old model (not a 1988), I do not have two connectors, I have one, with positions for six wires. With the lock on top, from the back of the connector, reading from top right to left: Blue/yellow, open (wire rotted out), Black/Yellow. Bottom right to left: Green, open (wire rotted out), Black/Red.
I have found the engine serial number and will do some more research over the next couple of days. So, the point of origin for the spark is the "magneto/"exciter" coil, is sent through the CDI unit, throught the coil, to the spark plug.... Is this correct?

 

[Saber6]

First thanks for the replies. I think moose may have some idea of what I am trying to say, but not to the full extent. This is a three wheeler that I doubt could even be used for parts. Oddly enough my interest is bringing it back to life, so I can kill it again. There are no fancy options such as ignition switch, engine stop switch, lights, secured seat, etc. What I do have is the motor, coil, CDI unit. I agree a wiring diagram would help in this case, but I refuse to spend more on a manual than what the bike is worth.

What is the minimum requirement to get a spark?
Does the spark come from the "exciter coil" ?

Moose, thanks for your support. I measured the CDI unit but the color codes do not match up because I think that the unit I have is for a very old model (not a 1988), I do not have two connectors, I have one, with positions for six wires. With the lock on top, from the back of the connector, reading from top right to left: Blue/yellow, open (wire rotted out), Black/Yellow. Bottom right to left: Green, open (wire rotted out), Black/Red.
I have found the engine serial number and will do some more research over the next couple of days. So, the point of origin for the spark is the "magneto/"exciter" coil, is sent through the CDI unit, throught the coil, to the spark plug.... Is this correct?

Thanks to duivendyk for this write up.Hope this helps.
In a CDI ignition system,a storage capacitor is charged to a high voltage (a few hundred volts) by the flywheel charging coil and, at the proper moment quickly discharged into the primary winding of the ignition coil,which is actually a stepup pulse-transformer.The secondary output is a short very high amplitude pulse which fires the spark plug.All these events take place during each engine revolution.The charging coil is usually located inside the flywheel,if there is room for it, but if the flywheel doubles as a cooling fan it has to be located outside.The spark timing is controlled by a small trigger coil located in close proximity to the flywheel which generates a low voltage pulse (actually two, a positive and a negative one), as the fly wheel magnet passes by.The circuitry in the CDI unit uses this pulse to close a solid state switch (usually a thyrister) to discharge the storage capacitor into the ignition coil primary and generate the high-voltage pulse at the secondary to fire the plug.This capacitor has previously been charged to a high voltage with the high energy pulse induced in the charging coil by the flywheel magnets.All these events take place every revolution.
Both the pick up coil and the power coil have two wires connected to them, one side of each goes to ground (usually coded black),they may be grounded internally in the magneto or connected together and brought out as a single wire and grounded outside or connected to a ground connection on the CDI unit.The two live outputs (charger coil output and trigger) are connected to the CDI unit.They can be identified by disconnecting them from the CDI and checking the resistance to ground with an Ohm meter.The trigger coil has low resistance,the charger coil higher (a few hundred Ohms typically).Both outputs are ac. signals!!,the charger output typically in the range of 100 V ac. DC measurements of this signal are MEANINGLESS and deceiving !,all they measure is the degree of asymmetry of the ac output,not the actual amplitude.Even simple multimeters have an ac position.The charger output is an unhealthy signal that could kill you under the right circumstances,sit on a wet saddle and grab the bare "white lead" for kicks. while riding around.This is not all that likely of course,but the output of the charger coil should be treated with respect.
I have never set eyes on one of these Chinese 2 stroke engines,so as far as color coding goes bear with me,I have concluded that the "tormentor" "white wire" is connected to the charge coil output and the "blue wire" is connected to the trigger coil.Shorting either one to ground will disable the ignition and stop the engine,in the first case the storage cap does not get charged,in the second it does not get discharged.Opening up the connections between these outputs and the CDI unit accomplishes the same thing,I would prefer shorting to ground esp., for the low level signal from the trigger output,a long lead would be connected to the CDI trigger input and a spurious signal could conceivably blow up the input device.Shorting them to ground does not hurt anything and is safer.I would use grounding connections going back to the engine ground and weather proof the switch and I would leave the output of the charging coil alone.It is probably possible to power other devices from the output of the charging coil,I think it could power a sophisticated high voltage low current dc circuit to minimise the drain on the coil feeding an efficient power convertor to convert this high voltage (50 V plus) to 12 or 6 volts power at higher currents.
Trouble shooting hints.Caution ,if testing for spark ALLWAYS have a plug connected with the shell grounded,never ever test with an open plug lead, you may destroy the ignition coil.
1) Disconnect leads going to kill switch (shorting mode hookup!) and try starting engine (Figure out how to stop it in case it runs) .
2)The charge coil and trigger coil are fairly robust devices and not likely to fail,measure resistance to ground (disconnect from CDI),if shorted or open circuit,they are defective or leads bad.
3) Ignition coil,disconnect from CDI if possible,measure resistance to ground of primary,should be a few ohms,measure secondary resistance to ground, should be a few thousand ohms.Caution: High resistance may be due to high resistance HT lead to plug!.Not easy to check unless you can get at coil output directly.
4) CDI unit,probably implicated if other tests OK
I hope that this post has shed some light on the mysteries of CDI ignition systems