I found the problem!

Eric2.0 · May 11, 2011

I got a new Multimeter and followed the instruction on this site. The CDI box is dead.

See this then read on...thank you.

96500873.mp4 video by Dirtcar28 - Photobucket

1) Check Ohms between BLACK wire and WHITE wire. Reading should be around 2 Ohms

*2.4 OHMS

2) Check ohms between BLUE wire and WHITE wire. Should be around 300-400 ohms.

*333 ohms on the 2k range...0 on the 200 range.*

CDI

1) Positive lead on BLUE wire and Negative lead on BLACK wire should read infinite (no activity)

*NO ACTIVITY*

2) Positive lead on BLACK wire and Negative lead on BLUE wire. Should be about 130-150 K-ohms

*NOTHING*

3) Positive lead on Spark Plug wire and negative lead on BLUE wire. Should read between 135-155 K-ohms

*NOTHING*

Switch to Low Scale 20K
4) Measure between Spark Plug wire and Black lead. Should be about 2.5 - 2.7 K- ohms

*PULLED 2.4 OHMS.*

I did the testing exactly as showed in 2Doors post with the meter ranges suggested. I believe the CDI is junk and want to upgrade... Who has a better quality CDI or could I use one off a car or lawn mower? I'm not geting another stock one..they are JUNK....Just the way the plug wire goes in proves how junky they are.

MotorBicycleRacing · May 11, 2011

Eric2.0 said:
I did the testing exactly as showed in 2Doors post with the meter ranges suggested. I believe the CDI is junk and want to upgrade... Who has a better quality CDI or could I use one off a car or lawn mower? I'm not geting another stock one..they are JUNK....Just the way the plug wire goes in proves how junky they are.

Did you get a "good" CDI and get your bike started?

I always found it kind of tricky to test CDI's so would test a
maybe bad CDI against a known good CDI.

I just swap them out as it's much faster and easier as I have lots
of parts including CDI's

Yeah, they are junk....lol another noob "expert"
Out of over 500 kits maybe one went bad and that
was a maybe.

Bad magnetos were much more common but still pretty
rare and they are easy to test.

If you got a bad CDI just buy another one, there is no
need to reinvent anything.
Someone has to get a bad CDI and maybe it was you?
Upgrade the plug wire, it is easy and looks better. lol

Let us know when you get it running. It will be a happy day.
Good luck.

Eric2.0 · May 11, 2011

I'm not getting another stock CDI.

I'm tempted to use one off a small Yamaha 2 stroke. Ignition coil

Eric2.0 · May 11, 2011

I'm going to put the one off my old snow-blower on there "just to see" If it runs I may just keep it there. I remember an old Yamaha dirt bike I had with a 125 on it and we put an old fashioned car coil on it....worked great for years.

The stock CDI for these things is 29 bucks.....I'm not taking another chance at a dead CDI at that price. Has to be other options.

Eric2.0 · May 11, 2011

This.... Wolf Pack Racing CDI Kit

Also I found this as a quote..

"Is there any possibility of danger to my engine by using this CDI? None at all. This is what the cheapskate Chinese should of put on it to begin with. Instead they included a CDI/coil combo that only advances (4 stroke style) and puts out the weakest of spark. Maybe they did this on purpose to keep the engine underpowered so it would pass legal requirements in most all countries."

AND THIS..

"Why is yours more expensive than some other CDI's? Because mine isn't made cheaply by slave labor in China. I value my employees and pay them well. Also my CDI, unlike all others, is especially designed for the Grubee engine. All others are either made for 4 strokes (that don't retard the timing at high rpm's) or they retard the timing over 7000 rpm (for heavily modified engines that rev up to at least 9000 rpm)."

I'm sorry, but those stock CDI are junk and I'm willing to shell out extra money for the American made CDI I linked too, because to make this bike more reliable for my dad(who is 67) is worth it to me.

Even has an MSD ignition wire... I'm so ordering this today.

rohmell · May 11, 2011

A regular ignition coil won't work, you need the CDI circuitry as well.

My opinion is to just get a replacement CDI box, just so that you can finally get the bike running properly and do some riding, then you can fine tune and experiment with CDIs and stuff later.

rohmell · May 11, 2011

Eric2.0 said:
The stock CDI for these things is 29 bucks.....I'm not taking another chance at a dead CDI at that price. Has to be other options.

$18.95 with free shipping with 7 day money back guarantee:

CDI Ignition Coil 80cc Motor Motorized Bicycle Bike | eBay

Eric2.0 · May 11, 2011

rohmell said:
$18.95 with free shipping with 7 day money back guarantee:

CDI Ignition Coil 80cc Motor Motorized Bicycle Bike | eBay

Just bought it. I hope that this one isn't a dead brick too.

Would you agree from my specs that my CDI is dead?

I'm just going to be so mad if that isn't the problem either.

rohmell · May 11, 2011

When in the Ohms ranges, some meters are polarized the same as the probes (red is positive and black is negative).
On some other meters, this is reversed (red is negative and black is positive)

So, to do an ohms test that says 'put the red lead here and the black lead here, and read the result' does not take into account how the meter applies its voltage to the probes, this could result in readings that are opposite of what you might expect from the test procedure, unless you are testing passive devices like resistors.

Some meters, usually the digital type, have too low a voltage available at the probes which will fail to activate a semiconductor device, these types of meters will have a 'Diode Test' function that is specifically designed to provide enough voltage for the semiconductor to go into conduction, and you can read the Vf on the display. If you have some diodes lying around, you can test them with the meter, and you will see what I mean.

Since the CDI contains semiconductor devices inside, your meter may or may not be triggering these devices into conduction, and that could be why you are not getting the readings stated in your test procedure.

You did say you have spark, so to me, the CDI is working somewhat. Perhaps you saw the spark when testing in air, and CDI might be weak and the spark is lost when trying to fire in compressed air inside the cylinder.

You never know, the CDI could have been assembled with floor sweepings, and is indeed weak.

If it was me, I would have bought a replacement CDI as well.

Here is more info:
http://www.hobby-hour.com/electronics/testing-semiconductors.php

Eric2.0 · May 11, 2011

Oh most likely it didn't trip the stupid whatever in the CDI box. I give up. Wait a week only to have the same deal with the new CDI.
I even got an extra Magneto just in case.

I don't get it. If it isn't the CDI box then I have no clue at all what is going on. I get **** loads of gas dripping out the pipe and a "sort of run" condition where I pedal for 100 feet, stop and the engine just goes.. Brrrrrmmm brmmmmm put put duh...dead. It's a very week sounding run, but it does try to run, sort of muffled like half the gas is igniting.

I don't know man....this is frustrating beyond belief with people looking at me like "is it running yet?" Pisses me off

Eric2.0 · May 11, 2011

To add insult to injury, My Neighbor asked me if I wanted a Huffy Big Daddy he got from the air base(Soldiers leave things behind)

Nice bike, but I told him I have my hands full with my current. I'd rather let a kid have the Huffy.

rohmell · May 11, 2011

Tomorrow I am gonna take the measurements off of my magneto and CDI using various different types of analog and digital meters and post a chart.

Electronic devices can sometimes be tricky to teat and diagnose out of circuit, so don't be upset about your test results.

This problem WILL be solved, and you WILL be riding very soon.

Eric2.0 · May 11, 2011

rohmell said:
Tomorrow I am gonna take the measurements off of my magneto and CDI using various different types of analog and digital meters and post a chart.

Electronic devices can sometimes be tricky to teat and diagnose out of circuit, so don't be upset about your test results.

This problem WILL be solved, and you WILL be riding very soon.

That would be very appreciated and great. Not only for me, but for others wanting to test these right. I assumed red positive black negative always....go figure...I just don't get why they would switch it.
Also my meter is new from Harbor Frieght(the best one they had) and it has vF-and all that stuff. Also a temperature meter and audible continuity test.
Again, thanks for taking measurements....I need to compare to something and know how to do it better.

At least the CDI is cheap $$ and I'll throw it on to see if it works...I just need to remember to not kick something if it doesn't work. :-||

rohmell · May 12, 2011

Here are the measurements that I took using three different digital multimeters that were at hand.
I did not have a chance to go into the warehouse and dig up the other digital and analog meters yet.

Here is the configuration of the probes, leads and meters:

1) Meter red to CDI blue, meter black to CDI black
2) Meter black to CDI blue, meter red to CDI black

3) Meter red to CDI HV,meter black to CDI black
4) Meter black to CDI HV, meter red to CDI black

5) Meter red to CDI HV, meter black to CDI blue
6) Meter black to CDI HV, meter red to CDI blue

1st reading is using Ohms function, 2nd reading is using diode test function.

Fluke 87V| DT-830B| Sears Craftsman # 82324

1) OL,OL | OL,OL | 1.3M,OL
2) 359.8K, .623 | OL, 640 | 1.3M, 601
3) 2.276K, 2.181 |2.27K, 1776 | 2.304K, 1156
4) 2.276K, 2.181 |2.27K, 1776 |2.304K, 1156
5) 361.7K,2.632 |OL, OL|9.39M, OL
6) OL,OL|OL,OL|OL,OL

I hope you can understand the above data chart.
The results you got are similar to my results when I used the DT-830B meter in Ohms function.

Try the diode test function on you meter and do the tests again.

Eric2.0 · May 12, 2011

Ok I'm using a Cen-Tech P37772 digital Multimeter. I turned the knob to the Diode symbol as that is all I saw having to do with diode testing. It was in the area of the ohm ranges.

This is what I got from following your guide to the tee.

1. Nothing, it just said 1
2. .592
3. 1.366
4. 1.367
5.1.610
6. Nothing, just says one.

I hope I did it right.... I used the function with the diode symbol...

Here's my ohms test.

1. 0
2. 196.2K
3. 2.47K
4. 2.48K
5. 198.4K
6. 0

Did my test with a brand new copper-top 9volt battery.

rohmell · May 12, 2011

On test #2 your resistance readings are lower than mine, suggesting some sort of internal difference but the diode test is the same looks like a silicon junction there (probably the input rectifier) but being defective is not conclusive.

On test #5, both your readings are lower than mine, suggesting some sort of internal difference (maybe defect?) with the CDI.
Your diode test reading shows something like one less junction in the Vf, so there might be one diode inside the CDI that is shorted internally.

My opinion is that the CDI has at least one component internally that is defective.

I have seen brand new diodes that have been shorted, possibly due to poor handling during shipping, assembly, etc, so it is possible that the diode was defective at the time of the assembly of the CDI.

I guess that they just put them together and throw them into the box without any pre shipment testing.

I think a replacement CDI will make your bike run correctly.

Eric2.0 · May 12, 2011

I'm so glad to hear you say that lol.

I have two CDI and one Coil coming in the mail(extra parts are good) since I'll be doing this forever once I get it going.

This explains the weak spark... It has a little something, but not quite enough.

rohmell · May 12, 2011

The resistance tests that you did on the coil look good, I think that part is OK, but it is always good to have spares.

Very sneaky trick, starting a new thread, to avoid exceeding you free 15 page limit.

biknut · May 12, 2011

When it comes to electronic parts testing with a multimeter isn't very reliable. Substituting is better.

Buy a CDI and magneto just in case.

Eric2.0 · May 12, 2011

rohmell said:
The resistance tests that you did on the coil look good, I think that part is OK, but it is always good to have spares.

Very sneaky trick, starting a new thread, to avoid exceeding you free 15 page limit.

For spares, yes...saves on shipping in the long run. Gotta be savvy these days.
A moderator should take my thread and this one, merge them and clean up chatter and make a nice "Frustrations of a new China Girl owner and his determined goal to get the B'tch started/plus how to use a multimeter"

lol.

biknut said:
When it comes to electronic parts testing with a multimeter isn't very reliable. Substituting is better.

Buy a CDI and magneto just in case.

I bought two CDI, one mag coil and a upgraded air filter from BFG(BoyGoFast)
I asked for a combined shipping, but I payed before that could be determined...crap...Shipping is expensive. I left BFG a note asking for combined shipping. Mayby he'll give me a return on the shipping.

Why doesn't Ebay have a cart option so you can add stuff and browse?

Spent over 17 dollars shipping on those items....

rohmell · May 12, 2011

Eric2.0 said:
Why doesn't Ebay have a cart option so you can add stuff and browse?

Spent over 17 dollars shipping on those items....

It does, kinda..after 'Buy It Now' you should have an option somewhere to continue shopping...
When all is said and done, there is another option "Request Total From Seller'

The seller can then combine shipping and whatnot, and then email you you an invoice.

I found the problem!

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