Failed CDI Unit

Hi All,

I own a '99 cbr900 whose cdi unit appears to be stuffed.

The bike wont start and the spark seems very weak across all cylinders.

What can cause these units to fail. Before I got to the expense of
replacing such an expensive item, I want to be sure their isnt another
underlying problem that has caused the unit to break.

Thanks,
Adam

 

Did you tour on it?

Hammo

 

Monkey says "boo hoo hoo".

Hammo

 

dog ... bone ...

 

I would maybe check somehere else 1st. Usully when the CDI unit fails it
fails completely.

Grab a multimeter and a Service Manual it will tell you have to check the
CDI unit.

 

yer...wot he said

multimeter, manual

check um pickup coils, wiring, ignition coils themselves, volts,
amps...but if its the CDI box its probably borked

what causes them to blow...being used an stuff

 

FUCKWIT!!

It's harsh week you know.

Hammo

 

Depending on the unit, it may need to be load tested, or you'll get
erroneous results.

Mind you, there isn't much room for luggage, so it can't be a tourer.

Hammo

 

Hammo toured on his Z1300... it caused almost exactly the same problem
as you have!


G-S

 

Before replacing the "mysterious black box":

a) clean all connectors with electrical contact cleaner.
b) disconnect kill switch wire at the CDI and see if problem
goes away. Sometimes it's just a leak in that
circuit.
c) make sure whatever feeds it power is working (are there
seperate CDI exciter windings on the generator? Are
they producing the specified voltage/resistance?)

It's suspicious that it's across all cylinders, because the thingummy
which usually seems to go is in the output stage.

-----sharks

 

Hammo also has spare CDIs. They are probably worth more than his bike!

Hammo

 

As has been said, bit sus cause usually when the CDI goes you don't get
anything (although I had a CDI get fried on my KR1 which gave an
erratic spark and some impressive backfiring). Betta Bikes in SA (look
em up, they're in the phonebook and online) can test and repair CDIs
and would be worth talking to given the price of a new unit.

 

Ditto Small Coil Rewinds in Geelong