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80 gs450: convert to points?

  • Thread starter Thread starter mlc216
  • Start date Start date
Ok I have another question... In the 4 stroke cycle there is an intake stroke (down), compression stroke (up), power stroke (down), and exhaust stroke (up)...

On a 180 deg crank:
If you look at one cylinder, it only needs the sparkplug to fire at the top of the compression stroke... as this fire happens and sends cylinder 1 into the power stroke, then cylinder two is coming up in its compression stroke. This creates a syncopated rythym instead of a steady beat. In other words it only needs to fire 2 of every 4 cycles... so does it actually fire every cycle and just have no effect when it fires at the top of the exhaust stroke? Or does the igniter take the signal and tell the coils only to fire every other signal for each cylinder?
 
Ok so this is the simple xs650 setup...
hei3ut4.gif
 
Ok... Cowboy has it, it's a wasted spark setup.

On a car, distributors don't run at crank speed, so are able to spark only when required.

As bikes generally are timed directly off the crank, they generally have a wasted spark setup.

This is a very simplified explanation but best I can do, I ain't a guru.

As to one or two circuits, the 180 degree firing order requires two separate circuits to function.

If you used one module, it would fire both cylinders simultaneously, meaning one cylinder would be firing 180 degrees out and you'd only end up running on one cylinder.

I suspect that would also result in other far more destructive results too, although not sure exactly what they would be.
 
I still don't understand how a system with two pickups and one pole fires any different than a system with one pickup and two poles.
 
Actually I just looked at your diagram again...

The way you have the second diagram will have both plugs firing at the same time.

The problem with this is that when the left cylinder is at the bottom of its stroke and the right cylinder is at the top of its stroke (180 degree crank remember), the spark will fire on both cylinders, which is 180 degrees out of time for the left cylinder. It needs to spark only at the top of its stroke.

Does that help at all?

I'm not very good at explaining this, although it does make sense in my head...
 
Yeah I don't know why it is so hard for me to understand. I guess with two pickups and one pole it fires two different signals so even though it has a wasted spark, the plug always fires at the top of the stroke. Got it. I think haha.
 
Yup you got it! Sorry my explanation was such crap... oh well... haha
 
pete said:
Yup you got it! Sorry my explanation was such crap... oh well... haha
Click to expand...

Aww pete your explanation was great man... But, I'm a mechanical engineer... not a electrical guy at all! :D
 
Haha I'm an IT geek... I occassionally remember to have some social skills... :rolleyes:
 
Maybe something like this would be handy? considering all advance is taken care of mechanically you dont have to be concerned about adjusting the timing curve and just taking that input and sending a pulse to the ignition coils. if you wanted to get really fancy and fix the mechanical advance and put in a computerised advance then you could consider something like this. I've considered doing it, but as it takes a fair amount of mucking with the harness and a bit of using the old grey matter i've left well enough alone and just stuck with the existing & functioning unit.
 
The only problem if you go down that path is the price... nearly half the price of the Boyer Bransden and it's a fully supported product.

However, I'm always a fan of the DIY stuff which is why I've persevered so far with the HEI modules. Now if only I could find a way to get my exhaust done and start testing that again...
 
Yeah I'm thinking that's a bit over my head for now... I'm more of a mechanical guy to begin with, so I think the last thing I want to do is add more complicated computer controlled modules to my bike...
 
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