Sparking ignition points

[Allie]

Well this is a great thread. I was actually looking to see if people were having trouble finding replacement points for our bikes, cause the ones for the 79 750 seem to be pretty scarce. Especially LH ones.

I'm not anxious to convert to electronic ignition but maybe I'll have to - unless it's just covid related shortage like millions of other things. I am already looking at going to resistor plugs as soon as I decide on leads and whether to replace the coil or not. I was thinking just caps at first but one of my leads has breaks in the insulation so...

I -did- replace my condensers recently after one of them obviously (to me anyway) was bad. It seemed to fix the problem for a red hot minute, then the misfiring returned. I looked at the plug caps and found a dead one (infinite resistance is, like, not groovy) -YES! But, it still runs rough. I messed around with point gap, got it to run better, then sanded the contacts with wet/dry - doesn't run??? Well this thread illuminated THAT issue. I've had that happen before now that I think of it, and didn't know why.

SO, although even a fuss penny such as myself just wants to replace the points and have done with it at this point, I guess I'm forced to go out and try to file the points with something else, and double check the condenser leads to make sure they're making good contact.

The day my condenser failed I could see crazy arcing on one side (especially at night) and the other points had occasional sparks. After replacing with aftermarket, both sides had more arcing than I am used to seeing, but nowhere near the Nikola Tesla Fever Dream that was happening before.

Today I was checking the timing and noted the timing light cutting out on Cyl 4, coinciding with low speed misfires. Cyl 3 was rock steady, along with Cyl 2 on the other side. Cyl 1, you guessed it, made the timing light flicker. That's what led me to widen the gap on the 1-4 points as it was a bit tight, and at the same time ruin the points with some we/dry. Now there's no sparking at the points, or the plugs, and no flicker from timing light - yay! For such a simple system there sure are a lot of ways to mess it up.

Hahah while I was waiting for the new plug cap I knocked the valve cover off and checked my clearances - I hadn't done that in a million years but they don't move as much these days. All quite acceptable except 3 and 4 exhaust are getting really close to bottom of tolerance. Too bad I have completely totally lost my little stash of shims. DAMN! I'm sure I have no possible idea where they are. That's really frustrating. Welp it's good till winter I'm sure...

Well thanks for letting me think out loud.

[Allie]

After replacing the bad plug cap, and replacing two plugs that had stupid high resistance, and finding some NOS points from Cycle Recycle, the bike ran, but like crap. Grrr... Just for fun I placed a .1 uf cap in parallel with the 1-4 condenser, and the bike perked right up! I found a decent condenser from a previous tune-up and replaced the band new one, and took it around the block. It didn't run great but at least it went. I pulled over and took that capacitor out of my pocket and jimmied it into the 2-3 circuit, and it ran MUCH better. I went back home and found another decent condenser and put that in, and it runs perfect now. So both of those aftermarket condensers are junk. So now I have do figure out which way to go before one of these goes, they're not spring chickens after all. Electronic ignition is looking better and better. For now I'll be carrying a couple of spare capacitors with clips soldered onto the leads...

This *@%^$*@%^$*@%^$*@%^$ has basically blown my summer.

[Big T]

Barring any more hurricanes, you should be able to get a lot of riding in before the snow flies

Your ordeal is what I try to explain to the " you can fix points on the road side, you can't fix a Dyna S" crowd
You can't fix a condenser, either, and that's more likely to fail.

[Allie]

I'll get my son to Hot Dog Johnnie's this year, for sure!

[Allie]

I've concluded that I will go with a Dyna S in the near future. I just don't see the point in staying with the stock system any more. In the mean time I've made a spare condenser out of two .1 uf 630v caps soldered in parallel to two alligator clips. If one of my old condensers go it's easy to clip into place as needed. These caps are rated to something like 105C but I guess it gets REALLY hot in that little space... I'd probably leave the cover off to get myself home. There's probably better (remote) options but this is a good stop gap.

Casual reading indicates that your condensers 'ring' at 300 ish volts so you actually want them rated much higher. I don't know exactly what that means except I guess when they discharge in use the 'pressure' is much higher than 12 volts and making close personal contact will really 'ring' your bell. Also most point ignitions use a condenser between .18 - .22 uf, and these are no different. I think Kokusan uses .19 and ND uses .21, something like that. It's in the shop manual. Also while too little capacitance causes arcing as the points open, too much can cause arcing as they close and discharge. So there is an optimal value, tho at casual riding I'd imagine it's pretty forgiving.

Lastly, with the good condensers installed I took careful note with the garage light out of the amount of arcing taking place at idle and moderate revving of the engine. That value = ZERO. At higher revs obviously you can get occasional arcs and bouncing but the baseline is no sparks!

This is just personal research and observation as I strive to better understand what's going on. YMMV.

Now for those front forks....

[gs11ezrydr]

I've concluded that I will go with a Dyna S in the near future. I just don't see the point in staying with the stock system any more. In the mean time I've made a spare condenser out of two .1 uf 630v caps soldered in parallel to two alligator clips. If one of my old condensers go it's easy to clip into place as needed. These caps are rated to something like 105C but I guess it gets REALLY hot in that little space... I'd probably leave the cover off to get myself home. There's probably better (remote) options but this is a good stop gap.

Casual reading indicates that your condensers 'ring' at 300 ish volts so you actually want them rated much higher. I don't know exactly what that means except I guess when they discharge in use the 'pressure' is much higher than 12 volts and making close personal contact will really 'ring' your bell. Also most point ignitions use a condenser between .18 - .22 uf, and these are no different. I think Kokusan uses .19 and ND uses .21, something like that. It's in the shop manual. Also while too little capacitance causes arcing as the points open, too much can cause arcing as they close and discharge. So there is an optimal value, tho at casual riding I'd imagine it's pretty forgiving.

Lastly, with the good condensers installed I took careful note with the garage light out of the amount of arcing taking place at idle and moderate revving of the engine. That value = ZERO. At higher revs obviously you can get occasional arcs and bouncing but the baseline is no sparks!

This is just personal research and observation as I strive to better understand what's going on. YMMV.

Now for those front forks....

Very good observations..The differences between ND and KOK....Thanks..Good info..I learned how much timing was important,when adding a little nitro with points in a 2 stroke, Constant headache ..Holed a lota pistons..lol..But yep a Dyna S probably the way to go..

[tatu]

If the points are not scrupulously clean they will arc. I clean mine with paper. I would not go with electronic. There's nothing wrong with points on these old bikes.
You can usually do something on the side of the road in the event of a problem with points ignition. A CDI there's no chance of a fix.

[Brendan W]

If the points are not scrupulously clean they will arc. I clean mine with paper. I would not go with electronic. There's nothing wrong with points on these old bikes.
You can usually do something on the side of the road in the event of a problem with points ignition. A CDI there's no chance of a fix.

Reminds me of a conversation with a dealer when I bought a new Citroen BX in 1990.
Why is there no tool kit ?
They are so reliable you won't need it and so complicated it wouldn't be of any use anyway!

[Allie]

If the points are not scrupulously clean they will arc. I clean mine with paper. I would not go with electronic. There's nothing wrong with points on these old bikes.
You can usually do something on the side of the road in the event of a problem with points ignition. A CDI there's no chance of a fix.

I hear what you're saying but right now at least, availability seems to be an issue with points AND condensers. Quality too.

[Big T]

If the points are not scrupulously clean they will arc. I clean mine with paper. I would not go with electronic. There's nothing wrong with points on these old bikes.
You can usually do something on the side of the road in the event of a problem with points ignition. A CDI there's no chance of a fix.

You can't fix bad condensers on the side of the road. That was Allies problem.

I haven't had to fix my Dyna in almost 40 years. I did check my timing back in 2008, it was still good

[Allie]

You can't fix bad condensers on the side of the road. That was Allies problem.

I haven't had to fix my Dyna in almost 40 years. I did check my timing back in 2008, it was still good

Well you can't fix them but you can replace them, there is that. The real issue right now is buying new ones, waiting for them to come, putting them in, and having them both fail half way to work your first trip. Not to mention the scarcity of points... I found a pair for less than $75 finally, and they turned out to be NOS... for a GS400. They do work just fine. After I ground one of the chassis down so it would slide past the adjustment nubs on my breaker plate. I'm happy enough with that but what happens when I can't even find that? Me, I'm stepping into the 1980s. YMMV.

[tatu]

Well you can't fix them but you can replace them, there is that. The real issue right now is buying new ones, waiting for them to come, putting them in, and having them both fail half way to work your first trip. Not to mention the scarcity of points... I found a pair for less than $75 finally, and they turned out to be NOS... for a GS400. They do work just fine. After I ground one of the chassis down so it would slide past the adjustment nubs on my breaker plate. I'm happy enough with that but what happens when I can't even find that? Me, I'm stepping into the 1980s. YMMV.

ebay.com comes up with heaps. I believe the same points are used 1000, 750, 550. I think the condensers vary a little but it doesn't matter they will all work. For those kinds of parts I would ALWAYS fit OEM certainly not cheapo copies. I know what you say about failing condensers, here in Kenya I've fitted new replacement ones in the past and they've failed in ultra quick time on the odd car. Though condensers you could probably source from an electronics shop that are probably made in a much better and modern way, the thing that cooks older ignitions is leaving the ignition switch on and not running the engine. I've never had any kind of ignition failure on my bikes, apart from worn points, I can't remember swapping the points often.

Look there's more on ebay than you can shake a stick at, in the US you're lucky because it's all at reasonable cost and plenty of it..
gs1000 ignition points | eBay
gs750 ignition points | eBay
gs750 condenser | eBay

[Allie]

ebay.com comes up with heaps. I believe the same points are used 1000, 750, 550. I think the condensers vary a little but it doesn't matter they will all work. For those kinds of parts I would ALWAYS fit OEM certainly not cheapo copies. I know what you say about failing condensers, here in Kenya I've fitted new replacement ones in the past and they've failed in ultra quick time on the odd car. Though condensers you could probably source from an electronics shop that are probably made in a much better and modern way, the thing that cooks older ignitions is leaving the ignition switch on and not running the engine. I've never had any kind of ignition failure on my bikes, apart from worn points, I can't remember swapping the points often.

Look there's more on ebay than you can shake a stick at, in the US you're lucky because it's all at reasonable cost and plenty of it..
gs1000 ignition points | eBay
gs750 ignition points | eBay
gs750 condenser | eBay

Points are less problematic than condensers granted. My issue right now is that I just don't trust what's out there in the way of condensers. If I really wanted to I could buy reliable substitutes from my local electronics store (THOSE are rare as hell these days too!) and try them out under the points cover or even mount them up by the coils. Both Mallory and IC make yellow axial lead polypropylene caps with a 105C temp and 600V rating... and self healing windings. I'm sure a way could be found to mount them permanently, and keep using points. For me I just don't think it's worth the hassle. I will be converting to the Dyna S soon, and I think the odds are pretty good that I'll never have to worry about it again. Hey if I'm wrong, I'm not throwing away my breaker plate or anything... but by then maybe I'll have an e-bike!

[tatu]

... but by then maybe I'll have an e-bike!

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[Allie]

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Santa's gonna end up in a e-Sleigh...