Ignition Question

I have a question for those who understand bike electrics, specifically the
ignition system.

A mate has just bought a Husky 610TE, 1993 model. It's had a tough life and
has been abused by previous owners and I'm currently helping him to get it
back to a good, reliable state.

Needless to say, it was running OK when we bought it (Friday last week) but
now refuses to start. To cut a long story short, the spark was getting
weaker over the course of the day (Satruday - we fixed a few oil leaks,
repacked mufflers, replaced stripped bolts, etc. etc, but did nothing to
stop it working, other than cleaning and gapping the original plug, to
specifications).

Eventually, we lost all spark. I was getting a weak spark through other
(incorrect size) plugs, so the first thing I did was replace the plug. $20
later, and a new Iridium plug (the bike shop saw my mate coming) we had it
running... like a beast!

This lasted for exactly 3 laps of the block, until a few nasty backfires and
then dead... no spark at all.

I am suspecting the coil, but I want to be sure that the stator is OK. I
don't know that I'm going to be able to get hold of another Husky coil for
testing without actually buying one, so I want to know if there's any way of
testing the output from the stator first.

Can someone point me in the right direction please?

 

Measure the coil resistance. Both 'sides' - primary and secondary.
eg - just some figures I made up so you have an idea of what to measure
Primary continuity - 20 ohms
Secondary continuity - 100,000 ohms

Primary to secondary insulation - 2,000,000 ohms (or more - depends on
how high you meter reads)
Primary to mount insulation - 2,000,000 ohms (or more - depends on how
high you meter reads)
Secondary to mount insulation - 2,000,000 ohms (or more - depends on how
high you meter reads)

Your measurements would have been done 'cold'. Warm the coil up - ride
the bike or use a hair dryer to get it warm .. not hot so it burns your
hand. Repeat the measurements and see if there is a 'significant change
(significant ? say more than 20% change)

While you measureing - check the stator resistance and any pick up coil
resistance .. while it is cold.
I think your saying that when the bike is cold everything is fine ..
once it warms up you have a problem?

 

Err, usually on single coils one end of the secondary has to be connected either
to ground or to one end of the primary. Secondary continuity is what you'll
measure between the HV (plug cable connection) of the coil and either of the
primary connections.

--
// Rik Steenwinkel '85 R80ST Skippy bike
// Enschede '91 R100GS/PD The Great Unwashed
// Netherlands '90 K75C Kommutabike
// "Far away is only far away '81 MZ TS250/1+LSW Badkuip
// if you don't go there" '79 Honda XL250S TBD
// N 52.2158 E 6.88589

 

Yep, yer correct there Rik.
I think the mount is still insulated from the coils though so that is
the only insulation test you can carry out with a simple ohm meter.