Yamaha Serow CDI

[Hugh]

Many thanks Ian, much appreciated.

TTFN

Hugh.

[bill_qaz]

Hugh, have you pulled the flywheel off and checked the ignition trigger

[Hugh]

Bill,

Thanks for the idea, yes it was sent away with the magneto and both were retuned within specification.

Ian has kindly sent to me a w/shop manual with some test specs. I am away until the weekend but when I return I will recheck. I will also recheck that the flywheel is rotating with the crankshaft, which I am sure that it is

My main thoughts are that the CDI is faulty but then I might be grasping at straws

Anybody out there got a spare 4JG 66A

TTFN

Hugh.

[steve the grease]

With respect , you should carry out all the checks and tests as per the manual before splashing out money on a new CDI, Just simple things but try undoing every plug in the ignition and spraying the contacts with contact cleaner , and then fit and unplug the connector a few times. There is probably a pulse generator, the earth connection , the live feed, the cut out switch, an altenator feed. If it was put away working , there is a good chance that the fault is just a poor connection on a pin somewhere, rather than a failed electronic circuit board. Was the bike put away wet, or in a damp shed maybe?

There is nothing more satisfying than fixing something for free, or peanuts, that would have cost a fortune at a dealers, and nothing more dissappointing than spending £80 on a part , that turns out not to be needed.

[SHarper]

I’ve come across a dodgy worn out ignition barrel before on an old Yamaha causing all sorts of problems.

[Hugh]

Greetings, thanks for the ideas folks. I will work on it again at the weekend and let you know if I find anything.

TTFN

[Hugh]

Greetings fellow head scratchers,

Update. Out of desperation and simply to rule it out of the equation I have had the magneto coil replaced, looks like a slightly stronger spark now but still only one spark

I have rechecked everything I can think of and every wire but still the original problem exists. I do not have any AC current out of the orange wire leading from the CDI to the coil so I am pretty sure that the CDI unit must be faulty. There is a firm over in Europe that advertises a test/replace service but before I throw any more money at this problem I wonder if anybody out there has a spare CDI for sale (or loan)? Alternatively, could I send my CDI to substitute and test on your bike?

I think that there may be slight differences in models depending upon the build so I am specifically looking for one marked 4JG 66A as per the photo on page 1. If you have an alternative unit then I might be able to figure out the wiring code

TTFN

Hugh.

[Hugh]

Greetings,

Finally it runs

Well, after replacing the battery, replacing the ignition coil, stripping the wiring loom, removing connectors and replacing by soldering wires together, rewiring the magneto coil, replacing the CDI with the very last one known in captivity in Europe, testing and retesting everything I finally removed and totally stripped down the ignition switch to give it a physical clean, put the switch back together (after spending 30 minutes looking for the key lock spring that flew out) and guess what - it started perfectly first push of the button.

I was about to give up, give my tools away and start think about taking up chess

Just goes to prove that you cannot simply trust meters and test readings.

TTFN

Hugh.

[garyboy]

.. and the prize goes to .. ..

I’ve come across a dodgy worn out ignition barrel before on an old Yamaha causing all sorts of problems.

[SHarper]

.. and the prize goes to .. ..

I’ve come across a dodgy worn out ignition barrel before on an old Yamaha causing all sorts of problems.

Yay! Do I win a prize?