Fried my CDI?

jayjmarlo

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Dec 1, 2012
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So I left my bike with the gas valve open and though I may have done so before this time a few days later I found gas coming out of the exhaust pipe dripping out. When I went to start it, it ran very rough and would barely even run at all. I acting like it was flooded or had gas in the system so I tried to keep on peddling and just run it clean for like 20 minutes but it never changed. Later I tried changing the spark plug and it seemed to almost try and run again but sounded like it wasn't getting spark or gas. Than it just quit, I pulled the spark plug and it acted the exact same. I tried to test the spark plug and it didn't look like it was getting spark (I un-threaded it and taped it to the head of the engine and pedaled looking for spark and saw none. My theory is I fried the CDI, coil or spark plug and it isn't getting spark. I was thinking the CDI the little black box that feeds the spark plug. Can anyone confirm before I order a new one? If you agree any recommendations on a good one?
 
if you think there is no spark, then hold the plug in your hand and your hand on the motor and roll the bike forward - if it bites your hand, the plug is bad - if it doesn't bite, then it's the CDI or magneto
 
those stock CDIs have weak spark which is hard to see in the daylight.
try it again at night.
and turn your bike upside down and turn the engine over to get the gas out of the crankcase.
 
throw out china plug, buy japanese plug (ngk)

check that the boot and lead are good. they rarely are. once again. new new, ngk!

check that all wires are well connected, that magneto (its on the engine...search) is well mounted to engine... you need a solid earth! ie, undo the screw that holds wire, sand spot, do back up...

check resistances on magneto... between black and frame-0, between black and blue, around 400, and if it has the white wire, cut it off!

rarely does the cdi itself fry. does happen, but its more just to do with component manufacturing.... theres always a certain percentage that die in the first five minutes. just like i-phones. theyre worse though, they have more bits to die! (and really do make people look stupid! :giggle:) )


just prop plug on cylinder head, lift rear wheel and give the pedal on your side of bike a quick kick...


the "weak spark" on a stock cdi still seems capable of jumping 10mm or more in my experience... over an inch at full throttle... then they fry!
 
I try and TRY, And ya do it again Headsmess, calling a COIL a magneto. The magneto has NO wires connected to it, IT's just a magnet that spins inside the coil;.And just so ya know Jayjmarlo, 99% of the time IT'S THE COIL. Yeah, CDI's go out too, IN ten years I've seen maybe two bad ones, Coils are $12 and sometimes free shipping. IF ya think ya got a lot of fuel in the case, Drain the tank and turn it upside down, pull the plug and turn the peddals turning the engine till no more gas comes out. And remember to ALWAYS turn off the petcock when ya park it.
Big Red.
 
no.

http://www.thefreedictionary.com/magneto

a MAGNETO is ANY device using a magnet and coil to produce alternating current, commonly in relation to ignition systems. the bit that spins is the ROTOR, be it a magnet or not.

the entire unit, that horseshoe bit of steel, the magnet, AND the coil of wire, are collectively called a magneto.

can also be called a dynamo, which is usually when its used simply as a generator.

the step up transformer that changes the low voltage to a high gap jumping voltage for the spark, is commonly called a coil. from "induction" or "rhumkorff" coil)

otherwise, i completely agree. more often than not the magneto is fried. the CDI unit itself, almost never!
 
if you think there is no spark, then hold the plug in your hand and your hand on the motor and roll the bike forward - if it bites your hand, the plug is bad - if it doesn't bite, then it's the CDI or magneto

frirend can u give me more detail as to what you mean ??? so if i get zapped by the plug in my hand holding it against the engine case and turn engine // does that mean the spark plug is bad??? i thought it meant it was ok??? because its producing spark
 
if you can feel the spark in your hand, but can't see a spark at the plug, then the problem is either a bad plug or you aren't turning the engine fast enough to see the spark

this test will not tell you if the CDI is timed right tho
 
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