CDI Bad?

M

MrSki

X
jetdude said:
I didnt replace any coils yet, just the CDI. I did pull the spark plug boots off the other day, when I pulled the enhancer, and trimmed the wires. I didnt try it yet though.
Click to expand...

The CDI is a coil - it is the spark plug coil...and it is not really a CDI. CDI means capacitive discharge ignition. Which only means the early versions of this type of ignition used a capacitor to store energy (voltage) to fire onto the primary spark plug coil winding. This voltage was something more than 12 volts (conventional point/breaker stule distributor) and more like 300-400 volts. You start out with more and 100:1 windings on the secondary side of the coil gave you 30K to 40K spark plug voltage - up a bit from a 10K conventional ignition.

Our systems don't use a capacitor (unless you have an old roost boost) and the stator coils provide the 300 or so volts to fire the "CDI" coil.

Well you changed the coil which would have to address the plug boot ends so hopefully it wiull work for you. But don't toss that old CDI as it might still be good.
 
S

sflsurfrider

MrSki said:
The CDI is a coil - it is the spark plug coil...and it is not really a CDI. CDI means capacitive discharge ignition. Which only means the early versions of this type of ignition used a capacitor to store energy (voltage) to fire onto the primary spark plug coil winding. This voltage was something more than 12 volts (conventional point/breaker stule distributor) and more like 300-400 volts. You start out with more and 100:1 windings on the secondary side of the coil gave you 30K to 40K spark plug voltage - up a bit from a 10K conventional ignition.

Our systems don't use a capacitor (unless you have an old roost boost) and the stator coils provide the 300 or so volts to fire the "CDI" coil.

Well you changed the coil which would have to address the plug boot ends so hopefully it wiull work for you. But don't toss that old CDI as it might still be good.
Click to expand...

superjets have a CDI and a coil.
 
Mouthfulloflake

Mouthfulloflake

ISJWTA member #2
Location
NW Arkansas
Ill bet this thread just got really confusing for Jetdude.

Someone post a pic of an electrical box opened, and show JetDude, and MrsSki what the CDI unit, ignition Coil, relay, and rectifier look like in there.

I think they BOTH might learn something.

:biggthumpup:




MrSki said:
The CDI is a coil - it is the spark plug coil...and it is not really a CDI. CDI means capacitive discharge ignition. Which only means the early versions of this type of ignition used a capacitor to store energy (voltage) to fire onto the primary spark plug coil winding. This voltage was something more than 12 volts (conventional point/breaker stule distributor) and more like 300-400 volts. You start out with more and 100:1 windings on the secondary side of the coil gave you 30K to 40K spark plug voltage - up a bit from a 10K conventional ignition.

Our systems don't use a capacitor (unless you have an old roost boost) and the stator coils provide the 300 or so volts to fire the "CDI" coil.

Well you changed the coil which would have to address the plug boot ends so hopefully it wiull work for you. But don't toss that old CDI as it might still be good.
Click to expand...
 
WAB

WAB

salty nuts
Location
coastal GA
Jetdude, if you want, PM me and I'll give you my #. Sometimes this stuff is easier to explain Verbally. But yes, the 'coil' we are referring to is in the E-box that the plug wires come out of.

On Kawa 650's the coil & CDi are one unit, but not on the Yamaha's.
 
The other Alex

The other Alex

(Jetdude)
Location
Lake St. Clair--
OK, by CDI I am talking about what the MSD Enhancer replaces. Ignition coil I was talking about where the spark plugs go to. Pulser Coil on the flywheel, and charge coil on the flywheel. I realize that there are a lot of coils, I didnt realize the CDI was a coil. Yamaha refers to it as the CDI unit, so thats what I was calling it.
I didnt touch the ignition coil yet, except for trim the spark plug leads.
 
Mouthfulloflake

Mouthfulloflake

ISJWTA member #2
Location
NW Arkansas
the CDI unit is NOT simply a coi.

its alot of things, its a CDI ignition unit.




jetdude said:
OK, by CDI I am talking about what the MSD Enhancer replaces. Ignition coil I was talking about where the spark plugs go to. Pulser Coil on the flywheel, and charge coil on the flywheel. I realize that there are a lot of coils, I didnt realize the CDI was a coil. Yamaha refers to it as the CDI unit, so thats what I was calling it.
I didnt touch the ignition coil yet, except for trim the spark plug leads.
Click to expand...
 
WAB

WAB

salty nuts
Location
coastal GA
jetdude said:
I havnt pulled the spark plugs, but the rear one was nice and hot, and the front one was warm, not quite cold, but not really hot.
Click to expand...
PLEASE, swap the wires to opposite cylinders and see if you get this same result in the opposite cylinders. It takes 2 seconds and will tell you if problem is the spark plug's coil or not.
 
M

MrSki

X
jetdude said:
OK, by CDI I am talking about what the MSD Enhancer replaces. Ignition coil I was talking about where the spark plugs go to. Pulser Coil on the flywheel, and charge coil on the flywheel. I realize that there are a lot of coils, I didnt realize the CDI was a coil. Yamaha refers to it as the CDI unit, so thats what I was calling it.
I didnt touch the ignition coil yet, except for trim the spark plug leads.
Click to expand...

Oh I see the confusion. There is a seperate controller on a stock SJ...my bad, didn't know. My 550 's spark coil has "CDI" written on the side so I thought that's what you meant particularly since myself and a couple others here keep pointing to that or the boots at the plugs.

However collectively, all the components together comprise the "CDI" which as I stated means Capacitive Discharge Ignition - the entire thing.

So you changed the controler then and it looks like you addressed the spark plug ends. I don't see yet where you tried to run it yet. Same comment though, if it was a bad boot connection, the MSD controller might still be good.
 
The other Alex

The other Alex

(Jetdude)
Location
Lake St. Clair--
I will swap the spark plug leads when I test it out tomorrow. I havnt run it yet, so I havnt had the chance too.
I always though that switching the leads could damage the ignition coil, no?
 
WAB

WAB

salty nuts
Location
coastal GA
No, they spark at the same time anyway.
You are supposed to keep the plugs grounded when turning it over with them out. The CDi, as Mrski described, builds up power from the 'charging' coil on the stator, and stores it to spark the plugs. Hence the 'captive discharge' name. With the plugs out & no place to ground it builds up & cooks the CDi.

But that does not sound like your problem with the way Yamaha's coil is seperate from the CDi. I do not *think* you can only fry one side with the CDi going bad, just with the coil going bad. Somebody please correct if that's not right.
 
M

MrSki

X
Yeah if the yami's twins fire like the kawi twins, both do spark at the same time. The energy under load only goes to one plug - the one with the nice moist A/F charge compressed around it (at TDC). The other one at BDC has no good electrons to flow across so it does nothing - all energy goes to the cylinder at TDC.
 
keefer

keefer

T1
Location
Tennessee
Dude, I want some of what you are smokin:439: The coil is wired in a dipole fashion. Like you said, both plugs fire at the same time, then you go on to say that only the plug with the A/F mixture at TDC gets all the energy??? and something about "no electrons" at the other plug?? Both plugs are still going to fire, the only difference on how many actual joules of energy of the spark will be determined by the resistance of the air gap of the spark plug. If in fact the cyl at TDC with the A/F mixture present has a lower electrical resistance, then the spark will contain more energy. The other plug will still fire unless it is shorted or fouled.

If jetdude has in fact tested the resistance across the plug caps, like I mentioned earlier, and it is within spec then the coil is probably good. With a good CDI, or controller, as you call it the ski should run if the stator is doing its job. I will bet after it is all over, he will find that he has some bad plug caps or wires that are arcing and breaking down under the stress of the high voltage.
 
The other Alex

The other Alex

(Jetdude)
Location
Lake St. Clair--
keefer said:
Dude, I want some of what you are smokin:439: The coil is wired in a dipole fashion. Like you said, both plugs fire at the same time, then you go on to say that only the plug with the A/F mixture at TDC gets all the energy??? and something about "no electrons" at the other plug?? Both plugs are still going to fire, the only difference on how many actual joules of energy of the spark will be determined by the resistance of the air gap of the spark plug. If in fact the cyl at TDC with the A/F mixture present has a lower electrical resistance, then the spark will contain more energy. The other plug will still fire unless it is shorted or fouled.

If jetdude has in fact tested the resistance across the plug caps, like I mentioned earlier, and it is within spec then the coil is probably good. With a good CDI, or controller, as you call it the ski should run if the stator is doing its job. I will bet after it is all over, he will find that he has some bad plug caps or wires that are arcing and breaking down under the stress of the high voltage.
Click to expand...

Damn when did you get so smart kid. I remember when you first baught that XP of yours... :biggthumpup:
 
S

sflsurfrider

MrSki said:
Yeah if the yami's twins fire like the kawi twins, both do spark at the same time. The energy under load only goes to one plug - the one with the nice moist A/F charge compressed around it (at TDC). The other one at BDC has no good electrons to flow across so it does nothing - all energy goes to the cylinder at TDC.
Click to expand...


:haha:

some people just shouldnt try to help. your theory on how an ignition coil works sounds like it came directly from the wadmouther.
 
M

MrSki

X
keefer said:
Dude, I want some of what you are smokin:439: The coil is wired in a dipole fashion. Like you said, both plugs fire at the same time, then you go on to say that only the plug with the A/F mixture at TDC gets all the energy??? and something about "no electrons" at the other plug?? Both plugs are still going to fire, the only difference on how many actual joules of energy of the spark will be determined by the resistance of the air gap of the spark plug. If in fact the cyl at TDC with the A/F mixture present has a lower electrical resistance, then the spark will contain more energy. The other plug will still fire unless it is shorted or fouled.

If jetdude has in fact tested the resistance across the plug caps, like I mentioned earlier, and it is within spec then the coil is probably good. With a good CDI, or controller, as you call it the ski should run if the stator is doing its job. I will bet after it is all over, he will find that he has some bad plug caps or wires that are arcing and breaking down under the stress of the high voltage.
Click to expand...


Your avtar depics you perfectly. You are a moron. You obviously do not have an engineering degree as I do - enough said.
 
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