coil testing

[wayno]

hi all, hope you had a merry xmas, been playing in the garage with my z1000 after reading various threads about carb set ups etc, firing on 3 cylinders when cold etc and decided to look at the plugs as it can run a bit lumpy when cold and found 1.2.3 are a bit sooty and 4 was wetwith petrol but this was cold, started up and it was sparking but i was not convinced that it was a good spark. put the plug back and started up put my hand on 1st exhaust and was getting hot fast tried 4 and was still cold but after about 30 secs started to get hot. decided after reading a bit more to look at the coils themselves and found this dont know if it will work!! [img]<a><img></a>[/img] is this normal as it appears to have melted/leaked from the coil on both. is there a way of checking these and what cylinders do each coil feed?

[wayno]

[knut]

doesn,t look good in photo but my eye sight is fading ,need a better photo when sitting on bike ,the lhs coil should be feeding cylinders 1&4 ,and rhs 2&3 if thats any help

[Garn 1]

Wayno, that leaking of goo from the coil, is a classic "tell-tale" that the coil has overheated. The usual cause is the regulator not working or not controlling the voltage enough. It is usual accompanied by a boiling dry battery.
However, this may have happened years ago and has been fixed, leaving the coil in this state, but still working. I would.......

Check battery (level & voltage... fully charged about 12.5V).
Start bike and check voltage across terminals is around 14.5 Volts at 3000RPM.... No more.
Check coil by measuring resistance as per manual and also check the there is no continuity between the primary and secondary. Check both coils so that you can compare.

Checking coils can be difficult as sometimes the trouble doesn't show until they are at working temperature. You might try swapping the coils so that they feed the opposite spark plugs (1&4 to 2&3 and vice-versa), if plug leads are long enough. I agree with you that if that spark doesn't look good, it usually isn't.
RegardZ

[wayno]

garn 1, the battery is new so level and voltage are ok, before i replace the tank to check the reg, how can i checkthe coil as the manual said to use a 3point coil tester, can it be done with a multimeter? do you mean to check continuity between primary and secondary by the 2 leads attatched to the coil?

[wayno]

if by continuity between primary and secondary you mean the 2 small soldered leads, then with the multimeter set to ohms i get 3.9 on one and 4.2 on the other

[Garn 1]

Wayno, forget about the 3 point coil tester... I think only auto electrians have those.

Check the primary resistance by connecting to the red/yellow and black, then check between the red/yellow and green, should be about 4 ohms (which is approx what you read) with multi meter.
Check the secondary resistance by connecting to the ends of both spak-plug leads from that coil (change the scale on multimeter to read kilo-ohms. should read about 30-40 kohms.

Both coils should read approx the same for both checks above.
Note: that these check do not check for breakdowns in insulation when working. hence, are not conclusive that is why we often swap the coils and check if problem is still on the same spark plugs.

One further check, is to check (singularly) the contuinuity beween the red/yellow, black and green wire to the disconnected spark-plug leads separately. I once found a new coil that gave me a reading on this test... it was replaced. Getting a reading meant that the primary and secondary insulation (from one another) had broken down and current could pass from the secondary to the primary. ....RegardZ

[wayno]

garn 1, checked secondary by setting multimeter to k2000 ohms and get about 24 on each coil, no continuity between red/yellow and black and green, checked voltage at 3000 rpm and got 16.9 volts so looks like the regulator is faulty

[Pigford]

A similar (hi-jack) question.... hope you don't mund chaps.....

Just checked my Lawson, and it only has a reading of 8.5 volts at the coils when ignition is switched on......

I did turn it over and it sort of ran for a few seconds and the volts jumped up, but as I'm still sorting the carbs & things it ain't running properly.

Is this normal

[chrisu]

sounds low.

seems like you're getting a big loss between battery and coils.

the wired george relay mod might be a useful way to go - or check/clean up all connectors/switchgear.

http://www.wgcarbs.com/index.php?option=com_content&task=view&id=12&Itemid=26