Firing order

Patton wrote:

....

The gif image moves pretty fast.
Here's a step-by-step.







Good Fortune!

I think it is running backwards. Take a look at the valve timing. The right hand valve opens immediately after the spark plug fires; but that is the power strike so both valves should be closed. Ed

I love that Patton has pictures for everything, always helpful. And he's right, one piston firing at a time, but the one matched with it is getting a spark anyways. The other just won't have anything to combust.

650ed wrote: I think it is running backwards. Take a look at the valve timing. The right hand valve opens immediately after the spark plug fires; but that is the power strike so both valves should be closed. Ed

As known, the compression stroke is where the piston rises to compress the mixture (both valves closed). Followed by the power stroke where the spark plug fires and drives the pistons downward (both valves closed).

Am thinking the image is trying to show both valves closed during the upward compression stroke and both valves also closed during the downward power stroke. At beginning of the exhaust stroke, the piston is already down (power stroke has ended) and the piston is just beginning to rise on the exhaust stroke and continue rising to push combustion residue out through the open exhaust valve.

Am not seeing the right hand valve opening until after conclusion of the power stroke.

But I may be missing Ed's point, as he has enjoyed considerable experience with the "backwards" running 650 BSA engine. :lol:
And don't KZ750 twin engines also run "backwards?"

Good Fortune!