Motorcycle Forum / General / Yamaha / February 2005

Hi all,

I don't suppose anyone out there knows how I can check out if there is a
problem with my CDI unit on my '80 250MX.  A week ago I used the kill switch
to cut the engine and - no more sparks.  Unfortunately that is how it has
stayed since.   I have checked out everything I can think of, the bike was
rebuilt recently and the wiring is in good condition.  I have checked for
breaks and bad earths but it all seems fine.  The rectifier and regulator
check out OK so I am left with the magneto or CDI (as I see it - suggestions
welcome).  I only have a Clymer manual which says 'get the CDI unit checked
out by a main dealer' but I don't think any of my local 'pile em high, sell
em cheap' dealers are worth a visit.

The CDI has 6 wires coming out - Orange, Black, Black/White, White/Red,
Brown and another unused black.  Does anyone know how I can check out the
CDI unit or the magneto.

Any advice appreciated, Paulie

PS - I am in the UK but I am pretty sure the UK and US models are very
similar.