problem with spark By jalat (Read 3,987 times)

[jalat]

Hi, my friend bought 1 year old and 2000 miles driven Jonway yy250t scooter. He got it really cheap an also got two big box brand new spare parts with him.

But the reason why he got it so cheap was because it was not working.
When ignition key was turned on not any light or any electric parts work.

We stripped all plastic off and started to check every connection and contact. Cleaned them and put contact protect. Finally the ignition lock assembly was the reason for no electricity. We changed new one and now we got lights and its cranking when trying to start.

But the problem is spark fading away.
The situation is that when we turn ignition key on at the same moment there comes one single spark.
And when we try to start, it gives one or two sparks and thats it. Then no more sparks until we first put ignition key off position and back on position.

Whole day we tried to figure out where is the problem.
We tried another cdi box. No help.
We tried another R/R. No help. (yes I know it does not effect starting)
We tried another coil for spark plug. No help. Same one spark only.

Tomorrow is another day and I tought that you masters might have good ideas what to check next.

I just figured out that could it be too big space between stator (magneto) and pick up coil?

So that when you try to start, first spark comes because of slow turning speed of magneto. And then magneto speed is so fast that too big pickup coil space is not reaching pulse anymore?
Didn't check that yet because it is now time to go sleep.

But then why it is giving that one spark when we turn ignition key on position?
My scooter does not do that.

Thank you for any help

[cruiser]

Good analysis, Jalat, but I don't think the pulse generator is adjustable. It sounds like you might be losing the DC input to the CDI. As a quick check, I would try jumping 12 volts off the battery directly to the black/grey or black (DC input) wire connector at the CDI and then try starting. If it keeps running, then this will be the problem. Checking the DC feed circuit to the CDI would be the next step.

[JR]

Good idea Cruiser and Jalat is this actually a non-euro version of the yy250t scooter? If so as mentioned by Cruiser the black wire gives it power after the key is turned on, also this is a DC powered CDI so if the power is fading or coming and going so will the spark.

Also another thought is the gray/white wire, this is the engine kill funtion, know you said you checked the connections but if that wire any where is got an open spot and touching ground even the slightest she'll shut down as this wire grounds out the CDI thus no spark. Also the engine off switch on the handlebars could be intermittingly closing the circuit and the gray/white wire goes to it too and you can simply unhook it from this switch and start the scooter to see if this is happening.

Again if this wire is touching ground it might only do it while the scooter is running and vibrating to ground?

Keep us up to date we are here to help.

JR

[jalat]

Thank you cruiser and JR.

This broken jonway is euro version too like mine. They are without diode and driving lights can be on without engine running.

I forgot to mention that we also tested kill switch on right handlebar and also tested kill switch from the side stand. Both were ok. And if there would be problem with any of those two kill switch then there would be no spark at all. I tested it with my own fully workin jonway yy250t.

We also tried it with my spare cdi-box and it acted a little different with it.

With origina cdi-box there was spark:
- when ignition key is ON (just one spark)
- when you pull break lever to turn on breaklight for starting (one spark)
- when crank one time or many timens (just one spark at first time)
- then no spark what ever you do before you turn ignition key off and back on.

With my spare cdi-box it gives spark a little different
- turn on key (one spark)
- pull break lever (one spark)
- hit start button one or many timen (couple of sparks every timen at the beginning when I push the start button)
- but if i crank over than 1 second it stops sparking until ignition key is set off and back on

Really weird thing.
We tested both cdi-boxes with my jonway yy250t (euro version also) and my jonway started and gave revs with both cdi. So I don't believe the problem is with cdi-box.

Four wires going to ignition switch were
- red (constant +12v)
- red/white (where 12v return when key is turned ON)
- black (if i remember right this was going to R/R)
- green (so it makes this ground)

But there was also two seapare wires at the front of the scooter. Green wire with male bullet type connector and black wire with female bullet type connector. Both wires are located near the ignition key wiring connector. At the beginning that green wire was connected with black wire and that did break the main fuse when ignition key was turned on. We checked every damn connector in the whole scooter. Cleaned every connector and of course this one connection was the last contact we separated Then fuse did not broke anymore.

With multimeter we measured that green was ground.
And that black wire was goin to the R/R black wire.
But black wire in ignition key connector also went to the same black wire in R/R.

We separated those wires and now we don't know where they should be connected. There is no other wires there at the front where they could go. Or should they be connected anywhere at all?
I don't know. These two wire are a big mystery.

Getting messy the whole thing. But good thing is that we have a lot of spare parts and we have fully working jonway yy250t right next to it so we can test different parts that are they working at all.


This jonway yy250t (euro version) wiring diagram that I found while ago shows that there should go only 3 + 1 wires to the cdi-box. But in this scooter and in my scooter there goes 3+2 wires.
.scooterdoc.proboards.com/index.cgi?board=elec&action=display&thread=4264" rel="nofollow" target="_blank">.scooterdoc.proboards.com/index.cgi?board=elec&action=display&thread=4264

But in this other wiring diagram there is 3+2 wires also in cdi-box.
i905.photobucket.com/albums/ac258/bashan_2010/DIAGRAMS/0108dcb1-1.jpg

I'm not sure where all these wires go from cdi-box and how to measure them with multimeter and measure against what? And what should be the values with multimeter.

I guess I also have to check with magnet that is the cdi-box DC or AC box.

[cruiser]

The bullet connectors with the green and black wires at the front of the scoot are just a spare or accessory key controlled power hook up. I have the same connectors on my scoot and they were not connected. I believe I used it for my LCD digital voltmeter.

Here's a link which should help out on the CDI as well as the electrical system in general:

thescooterprofessor.proboards.com/index.cgi?board=gele&action=display&thread=248

The CDI and schematic can be found on page 10.

[alleyoop]

Since you have a duplicate scoot that is working I would PLAY follow the leader, check the wireing that you believe is wrong with the good one.
Alleyoop

[JR]

Cruiser is right the two wires are accessorie wires and Cruiser is also right on the CDI on page 10, if you will see 5 wires 3 on one plug 2 on the other 3 plug = black/yellow, green, red/white, 2 plug = gray/white, and black.

The setup is as follows;
green = ground
black/yellow = sparkplug coil
red/white = stator trigger or pickup wire
black = 12vdc from ignition
gray/white = kill switch function

There are basically 4 versions of wiring on this scooter of course your euro version, the CF Moto version like Cruisers and my linhai version and here is another which I may think you have;

250T Benzhou Wiring Diagram

If you'll take note this have 5 CDI wires and is wired to have the headlights come on with just the key on unlike my and Cruisers scooter with lights on with the engine running.

You asked about what to ohm the first one I would ohm is the gray/white to the CDI and do it like this un-pin it from the plug put one lead of meter to ground the other to the gray/white wire set meter to ohms and turn the key on, with the key on you should have 0 resistance nothing if you have the slightest resistance then start looking for it, the wire could be rubbing up to ground even in the harness not just the frame.

Also as I said unplug this wire and try to start the scooter.

The ignition switch wiring is correct except the r/w wire is confusing and they may have done another color and if this is the case then the red/white is actually the gray/white on the schematic I just sent you which should be on the 2 plug with the black on the CDI?

Also what is not right the one spark when you turn the key on, it should only spark with the engine turning over. Check this also, where the wires exit out of the engine crankcase makes sure the rubber grommet is good and the wires have not rubbed together or to ground, had that happen to one guy before.

The pickup coil has no adjustment but could be going bad and not picking up enough siganl to properly tell the CDI when to fire but at this point I don't think this is it.

Again the black wire is 12vdc and if the voltage is erratic so will be the spark as the CDI recieves its power from the battery not the stator, ohm it out from the plug to the ignition and you should get full resistance.

Hang in there we'll figure it out!

JR

[jalat]

Thousand thanks already. We start digging this scooter

[cruiser]

Hi Jalat. The CDI responds to a change in voltage (a pulse or an on/off event) at the input from the pickup coil. This would most likely be a red/white wire. Measure at this point on the CDI for 12 volts after the ignition is turned on. There should be no voltage present. If there is then you have a short or miswire between 12 volts and the input from the pickup coil. This short would override any input from the pickup assuming the pickup coil is still hooked up correctly.

There should be DC only on the black wire with the ignition on.

[jalat]

Problem solved.
Last owner was connected two similar looking two wire connectors wrong. Wires were near cdi-box.
Another connector was the one which goes to auto choke.

We re-connected those wires as they should be and problem was gone. Nice clean spark and motor is running.
Now it needs a little adjusting or something, because it is bugging when we give a good revs. Maybe bad cdi-box or hole in carb diaphragm.

But this spark problem is now solved.
Thank you JR, cruiser and alleyoop

[JR]

Great job and I'm glad that diagram helped!

JR

[jalat]

Wiring diagram really was the reason to solve this issue. And good is we checked all contacts and cleaned them with contact protect spray. Now its electrics will be good "forever"
(until next time)