650SS Alazzurra ignition coils

[Wart]

Hello All,

I am in the process of rejuvenating a 1985 650SS Alazzurra.

The bike has been disassembled for a good long while (~20 years).

I recently got around to checking the ignition coils. These coils have "Motoplat bobina AT 12V" cast in their casing. The casing is some type of red plastic. I would guess these coils to be original equipment.

The service manual advises the following resistance specs for the coils: Primary coil = 8800 Ohms, Secondary coil = 40 Ohms.
Given these specifications, the coils on the Alazzurra are way off base! The coils on my bike yield: Primary coils = 5.4 & 5.5 Ohms, Secondary coils = 11,760 & 11,790 Ohms.

It doesn't surprise me that the original coils are out of spec, but it is curious that they have gone to the same resistance neighborhood in their old age. Perhaps that's how it works? A tribute to Motoplat's QC!

Bill

[Craig in France]

Hi Bill

The specified value for the primary (low tension) side of 40 ohms can't be correct - even tho' I too see it in the factory manual, written there in black and white!

4 ohms would be more like it. So your measured value of 5.5 ohms seems a tad high. But this may be a reflection of the accuracy of your meter. Low resistances aren't so easy to measure accurately.

The specified secondary (high tension) value seems about right. So your measured value may be a bit high. But better high than low.

And hey, if they work, they work ... :-)

Btw, the Pantah engines were originally fitted with Nippon Denso coils, the same as on the bevels. Only later on were Motoplat coils used. They don't have the best of reputations.

Ciao

Craig

[Wart]

Thank you Craig for your information an observations on these coils.

I'm distracted with getting the frame and wheels in order right now. I'll get back with those coils before too long.

I would like to have the finished product be reliable so the motoplats might have to go.

Try having this much fun with a new bike!

Tally ho,

Bill