Are my lobes right?

So I pulled off the valve cover to check the clearances, and i noticed that my lobes were opposite of eachother. not the intake to exhauts, but each cams lobes. does this mean that the cylinders fire separtely? cause I thought they fired at the same time.

forgot to say that its a 76 kz750 twin.And all the spacings were good but one. its supposed to be .05-.1mm but it was .102, should i still replace it?

750 twin?

Yes.

Wasted spark ignition,it will fire on every revolution.

Spin the engine over by hand after reassembly.
Watch the lobes,they will be facing each other on overlap(that will be at the start of the intake stroke).
And away from each other on the start of the compression stroke.

KZCool wrote:

forgot to say that its a 76 kz750 twin.And all the spacings were good but one. its supposed to be .05-.1mm but it was .102, should i still replace it?

You can get by with it if you don't have the correct shim available,but it should be set to within spec.

So they do fire separately?

KZCool wrote:

So they do fire separately?

yes.

As I recall, the pistons go up and down at the same time, but one is on a power stroke (just fired) while the other is on the intake stroke, then they do the opposite. Both spark plugs fire at the same time. When the plugs fire, one cylinder is just before TDC on the compression stroke, while the other is just finishing the exhaust stroke and preparing to intake. On the next revolution, the plugs fire again, but the cylinders are on opposite cycles, which is why the cam lobes are opposite. It sounds kinda complicated, but really it isn't.

P.S. When I first saw this thread, I thought you might be e Ferengi! :laugh:

KZCool wrote:

So I pulled off the valve cover to check the clearances, and i noticed that my lobes were opposite of eachother. not the intake to exhauts, but each cams lobes. does this mean that the cylinders fire separtely? cause I thought they fired at the same time.

On a twin, the pistons move side-by-side but fire at alternating TDC strokes. You get smoother power delivery that way. The spark plugs do both fire at every TDC stroke so there is a wasted spark on each exhaust stroke.

they are 180 degrees opposite and since your crank is going twice as fast it's okay:woohoo:

So is there any actual benifit to this?

KZCool wrote:

So is there any actual benefit to this?

Benefits of wasted spark design include only needing a single coil, and only a single set of points (or other signal), and no need for a distributor.

Spark on combusting cylinder is doing it's job igniting the compressed fuel/air mixture, while simultaneous spark on the other cylinder is wasted.

Good Fortune!