Starting problems

ringer · Post by **ringer** » 26 Oct 2009 22:33

Currently experiencing problems getting the bike started - once going, it runs fine. Each time I get on the bike, it seems to be a lottery whether it will start or not. When it won't start, I try bumping it, and eventually it gets going (but this can take up to 30 mins and a lot of effort). When it does eventually fire, it does it so easily, it is as if there never was a problem! I suspect a dodgy connection somewhere in the ignition circuit.

It seems there is no spark produced at the plugs. I want to analyse the ignition system, as detailed in the blue book, but that refers to an obsolete discharger (Siemens BI-C90). What can I use instead of this component that is both freely available and relatively cheap?

3potjohn · Post by **3potjohn** » 27 Oct 2009 06:43

What is the resistance from the green wire coming from the generator? I pull the wire from the fuse terminal and check between it and earth, mine was 185 ohms originally and the bike would need a few kicks,certainly never on the electric start, though it ran ok whereas now it is rewound it's 300 ohms and the bike starts without issue.

Steve Brown · Post by **Steve Brown** » 27 Oct 2009 18:28

Agree with threepot, and would add that if the coil checks out ok, maybe a de-magnetised flywheel? If this is the case, the battery charge rate will be reduced as well. Mine was like that from new, I think the battery was connected back to front at the pdi. Morphy Motors near Tring. They couldn't diagnose it and didn't really want to know. They aren't there now , wonder why?

ringer · Post by **ringer** » 13 Nov 2009 20:39

My ignition coil measures 236 ohms. Am now planning to rewind it to get it up to 300 ohms. Have purchased the wire from my local Maplins - they had it on the shelf at Â£8.40 for 250g of 0.125mm solderable enamelled wire. Just need to pluck up the courage to start the job - this bike is my daily runabout and I want to be sure I can dismantle the coil, rewind it and refit it quickly. Have been unable to find a source for new formers/bobbins so have to trust to luck that the original former will be ok to reuse.

But before I get started I want to analyse the ignition circuit as it is now, for later comparison. As in my original post, does anyone know of a suitable component to use to indicate if the coil is outputting the required 90V?

Another question - I'm sure I read a reference somewhere recently about the ignition circuit not producing a spark if the engine is spinning at less than 400rpm. Can anyone confirm this, or was I mistaken?