CDI box wears out

socialdistortionkid

socialdistortionkid

New Member
I am having a strange issue with my bike.

It runs for a about a tank of gas then out of nowhere it dies and will not restart because it has no spark. A New CDI makes it fire right up then it does the same thing.
It cant be the Spark plug because it works fine on my dirt bike.


Im thinking too much voltage is frying the CDI?

Anyone else ever had the same issue?
 
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Nobody seems be much help on this forum. I guess im the only motorized bicycle owner having this problem so i will be taking it to the bike shop tomarrow and letting Ez-Cruizer fix it =(
 
My hunch is that the magneto is heating up and when hot it develops either an open circuit or a short circuit internally. Either way it cannot send a signal to the CDI box until it cools back down.

If you let it cool down will it run again?
Problem only arises when the engine is hot?
 
GearNut said:
My hunch is that the magneto is heating up and when hot it develops either an open circuit or a short circuit internally. Either way it cannot send a signal to the CDI box until it cools back down.

If you let it cool down will it run again?
Problem only arises when the engine is hot?
Click to expand...

I can run this engine for 20 miles with a brand new CDI and it wont miss a beat. But after about a tank of gas it will just stop sparking while im riding leaving me stranded.

New CDI makes it run for a awhile. Im guessing it is grabbing too much voltage from it and slowly killing the CDI. Going to try new CDI and magneto and if thats not the fix i am going to buy a new engine.
 
If you build your own CDI, you can use heavy duty components that are less likely to fail, and you can tailor it to your riding habits.
 
I bought a new magneto and rotor. It never ran this good, it starts up sooner and has better acceleration.

I think this did the trick since it runs so good. I dont know which item fixed the problem because the mechanic installed both at the same time cause i wanted it fixed.

Salvaged the CDI box, he told me my CDI is fine. Now i have two extra CDI boxes just in case one takes a crap on me.
 
Try a spark plug with the letter "R" in it. Stands for Resistor.
So if it's a NGK B6HS, then ask them to look up the Resistor version of that plug.
So it may be B6HS R.
I am not sure of the terminology, but something to do with the high voltage electrical current flowing back through the lead.

The makers of another type of MB engine insist on a specific resistor plug for their CDI system or it won't run for long either.
 
Yes, i am familiar with The "R" series NGK plugs. I have run racing plugs in my dirtbikes and sea doos. Ive been using a BR8EG in my YZ125 for a few years with no problems whatsoever and thats the stock plug. The R stands for resistor, it resists plug fouling than the non racing plugs. Thats the only difference between the two plugs and i got that information on NGK`s website.

I running a NGK BR4HS plug in my bike currently. I also use autolite platinum plugs and i dont see any difference in power.
 
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Ok, that's good..process of elimination is what I'm getting at.

If you currently using the R plug and the CDI still stops working, keep it there and go on to the next probable cause, that might be wires and connections.
I solder the crimps on mine and never use the kit's handle bar kill switch, simply because I disagree with the way it "kills" the engine, (personal choice).
It's either direct wiring black on black, blue on blue, soldered and insulated.
If I choose to use a switch, then it's after market On/Off good quality toggle switch. And the blue wires are used to break the circuit.

If it still wrecks the CDI, then geez, can it be the magneto coil?
Chances are slim, but that's the only thing left, something faulty in that component that causes some sort of current flow disruption and it may cause that problem you mention with the CDI.
 
bikeroz said:
Ok, that's good..process of elimination is what I'm getting at.

If you currently using the R plug and the CDI still stops working, keep it there and go on to the next probable cause, that might be wires and connections.
I solder the crimps on mine and never use the kit's handle bar kill switch, simply because I disagree with the way it "kills" the engine, (personal choice).
It's either direct wiring black on black, blue on blue, soldered and insulated.
If I choose to use a switch, then it's after market On/Off good quality toggle switch. And the blue wires are used to break the circuit.

If it still wrecks the CDI, then geez, can it be the magneto coil?
Chances are slim, but that's the only thing left, something faulty in that component that causes some sort of current flow disruption and it may cause that problem you mention with the CDI.
Click to expand...

Well the shop put a new rotor and magneto and it runs better than before so i dont think it should quit this time. It has an air leak but thats off topic
 
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