Repeat Condenser Failure

[shields17]

I've got a UK 1979 GS850 that has had a running issue that I've been unable to solve. Having replaced the coils, plugs, condensers and points the bike returned to running properly. A couple of rides later the issue returned. Pulling the plugs showed that 1 and 4 were not firing correctly. I then took the "new" 1&4 condenser off and put the old 2&3 condenser in its place. The bike ran well for around 3-4 miles before issues returned.

There's lots of reports of poor quality replacement condensers but as it's always the 1&4 that fails it seems like the bike is destroying that condenser repeatedly. Are there any common causes of this behaviour?

[sam000lee]

What coils did you install? I would start by inspecting the wiring + connections between the points and the coils.

[shields17]

The coils are Hendler Brand marked 540612H. Having just googled them they give P:5.11 ohms and S:17.55K ohms. This does seem a little high compared to the service manual 4 and 15K but wouldn't explain only 1&4 having issues whilst 2&3 are fine.

[roeme]

The coils are Hendler Brand marked 540612H. Having just googled them they give P:5.11 ohms and S:17.55K ohms. This does seem a little high compared to the service manual 4 and 15K but wouldn't explain only 1&4 having issues whilst 2&3 are fine.

You need to measure them, not google them.

Additionally, coil resistance while measuring with a multimeter only gives half of the picture. A slightly higher/lower resistance will result in either much more or much less work for the capacitors/condensers.

Also, measure spark plug caps. From your description, it seems you haven't replaced them - correct?

Make sure not to combine resistor plugs and caps. It's either/or. (While it may work in most cases, you won't do yourself or the ignition any favours).

[zed1015]

I would just dump the points and fit a Dyna 'S' and coils.
Fit and forget.
Stronger spark, easier starting and more power.

[Gorminrider]

The coils are Hendler Brand marked 540612H. Having just googled them they give P:5.11 ohms and S:17.55K ohms. This does seem a little high compared to the service manual 4 and 15K but wouldn't explain only 1&4 having issues whilst 2&3 are fine.

Not a big expert, but the ratio of primary to secondary is about the same...the extra windings in the Hendlers have some consequences that you can explore as a theory (maybe just a different condenser-with more uf) but I think I'd concentrate on finding a difference between why one ignition circuit is failing, and the other not, firstly through the through primarie circuit (points,coils capacitors,and wiring), secondly through your hi-tension circuit as components( hi-tension leads plugs, caps),

[shields17]

Thanks for all the ideas of places to start!

You need to measure them, not google them.

Additionally, coil resistance while measuring with a multimeter only gives half of the picture. A slightly higher/lower resistance will result in either much more or much less work for the capacitors/condensers.

Also, measure spark plug caps. From your description, it seems you haven't replaced them - correct?

Make sure not to combine resistor plugs and caps. It's either/or. (While it may work in most cases, you won't do yourself or the ignition any favours).

Sorry yes I will measure them too, I was just noting the manufacturer spec was a higher resistance than Suzuki specs. Spark plug caps have also been replaced - I will double check they are compatible with the plugs.

Not a big expert, but the ratio of primary to secondary is about the same...the extra windings in the Hendlers have some consequences that you can explore as a theory (maybe just a different condenser-with more uf) but I think I'd concentrate on finding a difference between why one ignition circuit is failing, and the other not, firstly through the through primarie circuit (points,coils capacitors,and wiring), secondly through your hi-tension circuit as components( hi-tension leads plugs, caps),

Yes this is what I was thinking as the entire ignition circuit has been replaced with identical components yet the 1&4 continue to fail. I'll do some more testing of it over the weekend.

[Gorminrider]

You could maybe swap the coils too? keeping as much "in place" as you can for the swap.....and, I guess it's possible that a new coil is defective but gee I'd have to try every thing else first..

[shields17]

All the connections were checked today and noticed that the bolt that secures the wires to the points was stripped and not tightened down properly which hadn't been spotted before. Once this was replaced the bike is now running perfectly again having been out twice for around 25 miles each time.

So perhaps it was a bit quick to presume the condenser was failing and maybe just poor quality hardware on the new non OEM points allowing the connection the break. That doesn't explain what failed the first time the bike played up but hopefully now resolved! Whilst it would be nice to keep the original style points ignition on the bike it may be a good time to look at a Dynatek system, even just for the peace of mind when taking the bike a bit further from home.

[Gorminrider]

You found it! Good man!
......There's an argument for each: "Points" have travelled many continents before the transistor was ever dreamed of....I even know people that want to get rid of the black box and re-install points! me, I'm fond of solidstate ignition but points are ..reliable and "accessible" (like baroque music) and cheap too, while a black box is just that- a blackbox. Look at it and wonder, unless you carry a spare.