Roketa 250cc starting problem By bdplayer81 (Read 9,261 times)

[bdplayer81]

I tested the wires by touching it to the black/brown wire and the ground and it showed 12.45v on the volt meter. The CDI plug is at the front of the scoot and the battery is under the seat so I couldn't test it by putting the black lead to the negative on the battery. I didn't have anything I could reach to make the connection. Also, the ground off the battery appears to be attached to the case on the engine casing so that should be on a good clean metal surface.

[bdplayer81]

I plugged the CDI back in and checked the black/brown wired where it plugs into the ignition coil and I got 12.15v. (The battery was at 12.25v) Then when I grabbed the brake to start it the voltage dropped down to 9.5 or so. I plugged the black/brown wire back in and then checked the voltage on the spark plug wire and it was about 12.15v. I then hit the starter a couple times and the voltage was at about 7.3v. It seems like the voltage really drops when the brake is squeezed and the starter is cranked.

[prodigit]

Starter consumes a lot of power.
If brake lights bring the battery down to 9.4V, means that your battery is either bad, or de-charged (empty).
Just go to a gas station, and ask to charge the battery; or jumpstart your bike by connecting the leads to a car battery (car does not have to be running). You can remove the clamps as soon as the bike is running (as the alternator supposed to charge the battery).

When jump starting (with car battery), or with charged battery, and the bike does not start, try to see if you can hear the starter engage.

[JR]

Jul 30, 2012 18:47:48 GMT -6 bdplayer81 said:

I plugged the CDI back in and checked the black/brown wired where it plugs into the ignition coil and I got 12.15v. (The battery was at 12.25v) Then when I grabbed the brake to start it the voltage dropped down to 9.5 or so. I plugged the black/brown wire back in and then checked the voltage on the spark plug wire and it was about 12.15v. I then hit the starter a couple times and the voltage was at about 7.3v. It seems like the voltage really drops when the brake is squeezed and the starter is cranked.

Ok the CDI test is good so we are getting voltage to the CDI like we should.

Now by what you've just described is a classic bad connection either on the starter circuit on either side the hot side or negative side. Also it could be the batery with a dead cell?

Got to go through the battery connections on the positive side to the starter relay and from the starter relay to the starter itself.

Then you've got to go through the ground side. You mentioned where the battery negative cable is hooked up. Got to unhook it and make sure this spot is clean of paint and making a good connection. alos make sure there is a cable from the negative side of the battery going to the engine block itself, the engine MUST be grounded.

Lastly you need to have this battery load tested at a auto parts to make sure it will hold voltage under a load.

JR

[bdplayer81]

I checked the positive side of the battery connections to the starter relay and to the starter. Just to make sure I did it correctly... I had the red lead on the connection on the relay and then the black on the negative post on the battery. Then did the same thing for the connection to the starter. Red on the starter connection and black on negative post. Each time the voltage read over 12v. I then checked the ground off the battery by putting the black lead on the ground and the red lead on the positive post which resulted in voltage over 12v. As far as grounds coming off the battery there was only one and as I said before, it connected to a bolt holding the crank case housing together. Is that adequate for grounding the engine? Also, there isn't a ground on the frame from the battery to the frame. Does there need to be one? The only ground wire connected to the frame is connected to the bolt/nut that holds the ignition coil on which I think is coming from the CDI plug. I'll be taking the battery in this week to get it checked out.

[bdplayer81]

Just got the battery checked. They told me it's good.

[bdplayer81]

I neglected to mention earlier and I did the test with the ground and the green wire. I set my volt meter to ohms and it read 1. I put the red lead on the green/white and the black on the ground. Then when I turned the key on nothing changed, it still said 1. I'm guessing this is an indication it did not lose continuity.

[JR]

Jul 31, 2012 21:49:21 GMT -6 bdplayer81 said:

I checked the positive side of the battery connections to the starter relay and to the starter. Just to make sure I did it correctly... I had the red lead on the connection on the relay and then the black on the negative post on the battery. Then did the same thing for the connection to the starter. Red on the starter connection and black on negative post. Each time the voltage read over 12v. I then checked the ground off the battery by putting the black lead on the ground and the red lead on the positive post which resulted in voltage over 12v. As far as grounds coming off the battery there was only one and as I said before, it connected to a bolt holding the crank case housing together. Is that adequate for grounding the engine? Also, there isn't a ground on the frame from the battery to the frame. Does there need to be one? The only ground wire connected to the frame is connected to the bolt/nut that holds the ignition coil on which I think is coming from the CDI plug. I'll be taking the battery in this week to get it checked out.

Yes!! You need a ground wire from the negative side of the battery run to the frame. Find a place to bolt one on and make sure this spot is clean and no paint on it. The green wire you mentioned that bolted on with the coil needs to bolt up to this spot also.

Then from the frame where you have the battery cable bolted to you need a wire run from here to the engine also.

The frame and engine have got to be grounded.

JR

[bdplayer81]

If I put the red lead on the volt meter on the positive terminal and the black lead on either the frame or the engine block and get a 12.5v reading that's an indication that both are grounded, correct? For the record, I haven't changed any of the ground wires yet. They're still setup as they were from the factory.

[JR]

Well it's a indication that your negative battery cable (usually black) is grounded. But you need to remember that when reading it with a volt meter it doesn't take much of a ground to get a volt reading because you are not under a amp load.

That's why we have told you to be sure to check where the ground wires are hooked up that the contact is clean and paint free. When you try to start it the starter requires a good amount of amps to turn the engine over known as cold cranking amps (CCA) on a battery.

If there is a poor connection anywhere in the starting circuit on the ground side or even the positive side going to the starter then it will "load up" and it acts just like a weak battery trying to start your scooter. This alone will pull your battery down if it is put under too much load demand.

Go through the entire wire system of the starter and grounds and lets see if we can get this starter turning over like it should.

Also now that we know we have 12Vdc on the feed wire to the CDI lets check the ground wire on it too. The green wire on the CDI is the ground. Take your volt meter and put the red lead on the positive terminal of the battery and the black volt meter lead on the green wire to the CDI. If all is well you should read 12Vdc+ on your meter.

JR

[bdplayer81]

The ground wire on the CDI is good. I got 12.2v on it when I tested it (the battery was at 12.2v). The starter is turning over fine as well but still no spark.

[JR]

OK so we are narrowing it down to just a couple of possibilites or so. We have voltage and a good ground to the CDI starter turning over well so now we've got to see if the CDI is being grounded out by a possible one of three things;

Bad key switch
bad emergency kill switch (on handle bars)
gray/white engine kill wire grounded out.

So lets do this simple test.

(1) Take and set you volt meter to the ohms setting
(2) Make sure key switch is off and emergency kill siwtch is in the run position
(3) Put red lead of volt meter to the gray/white wire on CDI, put black lead of meter on the green wire to CDI. You should read 100% continuity
(4) With both volt meter leads hooked up to the CDI where I just mentioned turn the key switch on, if all is well you should get no continuity, if this is so then do test 5
(5) With both leads still hooked up to the CDI and with the key switch on turn the emergency kill switch to the off position, you should immediately get full continuity.

Now if at any time the tests do not go as I stated then here is one more thing we can do to see if the engine kill wire (gray/white is shorted out somewhere.

Remove the plug to the CDI with the gray/white wire, take a small tiny screwdriver and insert into the slot on the end of the plug and push it in to make the pin come out of the plug. In other words remove the gray/white wire.

Test the scooter at the spark plug to see if it will spark. If it sparks with the gray/white wire pulled out then you've got to find out why the gray/white wire is shorted out.

JR

[bdplayer81]

I tried the tests and when I put the red lead to the green/white wire and the black to the green I did not get continuity. I did pull the green white wire out of the CDI plug and plugged it into the CDI and still did not get a spark.

One question I wanted to bring up was the CDI. The mechanic did try a different CDI but they do not look the same. In the picture the factory CDI is the one with the white tape on it and the one the mechanic replaced it with is on the right. I'm wondering if the original CDI is bad but the one the mechanic tried will not work.

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[JR]

I did pull the green white wire out of the CDI plug and plugged it into the CDI and still did not get a spark.

I think you meant to say that with the green/white wire unplugged from the CDI you still had no spark? If this is so then for sure that's not the problem.

OK let's review what we know:

We have good 12Vdc voltage to the CDI
We have a good ground to the CDI
If you did unplug the green/white wire to the CDI and no spark then that's not the problem.

You now have questions about the CDI the mechanic used and my answer is I don't know? It appears the same except that the plug is on the other side. Did you look at the plug anf see if it has the same number of terminal pins to match your old CDI?

At this point there is only one more test to do and it's very simple to make sure everything is OK with the scooter's functions to the CDI.

When you started this you said that if the battery was fully charged the scooter would crank and run for a bit and then it wouldn't run again until you fully charged the battery. So the thought would be that your scooter isn't charging and when the battery goes down since it is a DC type CDI we needed to make sure we have a good battery and it's charging correctly.

But now you have no spark at all since the trip to the mechanic.

So let's do one more simple test;

Take your volt meter and set it on AC volts a low setting and put the red lead on the blue/yellow wire and the black lead on a good ground.

Make sure the battery is charged good so the scooter will spin over good.

With your volt meter hooked up turn the engine over and take a reading. This will be a very low voltage between as low as 0.5 to 2.5 AC volts if all is well.

This is the pick up coil or pulse coil. It sends a message to your CDI as to when to fire. If you have a good reading then we now have only two possibilities.

With no spark he either sold you the wrong CDI or it is bad and your old CDI is bad or going bad.

I would just for kicks plug the old CDI back in and see if you have even a weak spark, if so and you have no spark at all with the new one then you got the answer you was looking for in the picture.

If the pulse coil test is OK then with no spark or a weak spark with the two CDI's you have it's time to get a correct working CDI.

[bdplayer81]

I did the test and I barely got a reading and nothing over .3v.