Both coils failed?

[Magster]

Hi all, if any of you happened to see my intro I have just about completed my F2 cafe racer build.
It has not had a proper run yet as it has been running mainly on 3 cylinders. I was trying to narrow it down today and all plugs and checked sparks again which I knew I had before but after removing them and cleaning them I discovered I was only running on 2 and 3.  No spark on 1 and 4. Checked points and timing was ok although they were sparking not sure if good or not. Tried swapping condensers around as they seemed to be identical. Then no spark whatsoever! Swapped back again nothing. I am not sure how to test condensers but read up on how to check coils.
Checked voltage at coils black and whites 12v getting there. Checked resistance of primary coils b/w to yellow and b/w to blue and around 7 ohms at both ( ok I think?)  but no secondary  whatsoever. I gather I should be on 20k and should be able to use either wire to ht end but nothing at all. I am very close to ordering a couple but would like to check I have not done anything stupid. I have gone from a bike running on 3 mostly to 0 in the space of a day.
Would switching condensers have killed the coils? I guess it is nearly 40 and hasn't been run in 20 years but I was under the impression coils rarely actually failed.
Any help appreciated
Cheers, Magnus.

[JamesH]

Check the impedance (on the 20 kOhm meter setting) across each pair of ht leads coming from each coil (so stick the probes on the core wire in each ht lead with the plug caps removed). Should read 14-15 kOhms. Then go from there...

[Magster]

Thanks for that.
I have done it now and get 19k is that passable?
So does that mean my coils are ok and something else has gone wrong?
Would bad condensers stop it from sparking comlpetely at the plug?

Cheers,

Magnus.

[royhall]

19K is probably close enough if your using a cheap multimeter as they are not too accurate in that setting. A damaged condenser wouldn't stop a spark being generated in a test situation, whilst running the points would arc like mad if the condenser has gone. I would check the low tension circuit first as Honda coils are very reliable (although they do break), you may just have a bad connection. Are you HT leads long enough to be able to swap your coils around temporarily to see if the problem swaps to the other cylinders. I assume you have cleaned and set the points correctly?

[Bryanj]

Possible you put the condenser leads in the wrong place when you swapped them?

[Chris400F]

Possible you put the condenser leads in the wrong place when you swapped them?

If that is the case then we have been here before ....
See page 3 of this thread for the correct order for connections: http://www.sohc.co.uk/index.php/topic,10679.msg80415.html#msg80415

[Magster]

Thanks for the info.

I checked the condenser wires and sure enough I had pushed them on a bit too far and the connector was just touching the bracket.
Success I thought. Checked for sparks and was getting them on 2 and 3 but not 1 and 4. Double checked timing redid connections for 1 and 4 and tried all again. No sparks anywhere.
Must be something going on at the timing side. I should probably buy new points and condensers and set the whole thing up again.

Thanks for the comments.

Magnus.

[royhall]

In a test situation you could remove the points and short the circuit with a piece of wire and see if you get a spark.

[Magster]

Could you explain in more detail how you would go about that spark test?

I appreciate you all taking the time to respond to my plea for help.

Cheers,

Magnus.

[royhall]

All a set of points is, is a mechanical switch. If you remove the points you can then use the supply cable that goes to the points to short to earth manually. Do that and see if the coils discharge. If they do, you then know the ignition circuits are good and its therefore the points or condensers that can then be renewed. Hope that makes sense, works for me but a little difficult to put into words.

[Magster]

Thanks for that but I think I have just discovered the problem.
I had the spark plug caps reomved and when I was turning the engine over I saw the spark jump fully 10mm from the end of the cable to the cam cover.
I tried them all off and got a big spark from every one.
I assume it must be the plug caps. These were new a few months ago and I have had the bike running so unless they have gone faulty it must be the wire to cap connection being poor.

Thanks for taking the time to help me.

Cheers,

Magnus.

[royhall]

Glad you got sorted. Easy fix in the end!

[JamesH]

Well done magnus...