I was studying the Harley firing sequence and became confused as to how (or when) the old dual fire was occuring at one point in the cycle. But now I think I have figured out my delimna since the actual ignition usually occurs several degrees before TDC.

 

If you can find me the part number for a radiator on a 72 Volkswagen Bug I will tell ya.....

 

I think what they mean by single fire is that although one piston is on the exhaust stoke and the other is coming up to fire, the coil fires both cylinders simultaneously. One is to fire the fuel load and the other helps to burn any unburned fuel before it gets out of the cylinder on the exhaust side in order to help epa and it means less wiring in the ignition sytem. They don't fire the power stroke on the same revolution, they fire each time but the power is one revolution apart from each other. Dang-- I hope that made sense

 

I so wanted to say 1, 2
I agree with JAXDWG. although I don't know if it was for epa reasons.

 

I'm not positive about the epa thing but they do the double fire thing on a lot of 4 cylinder cars for the epa reason. 2.3 ford dual fire 8 plug 4 cylinder as an example and the same dual firing takes place on the chevy 2.2-----

 

That would be part # zero as in never made.
So then now it's your turn to comment on the sequence.

(I still say VWs are the best 4 wheel buy on the rode nowadays, selling for $17000.oo as opposed to $22,000.oo and up for some of the other glorified go carts.) And the VW has loads of head room for a tall person.

 

I bought a brand new Super Beetle in 1971 from a Volkswagen dealer. Out the door it was $1700. And as I peeled off those 17 one hundred dollar bills I thought man, this is a lot of frigging money, LOL!

 

Here is a decent explanation of the Harley firing order. This is what HD has a patent on that gives a HD it's distinct sound.

http://www.wildwestcycle.com/f_firing.html

http://www.freerepublic.com/focus/f-chat/1464309/posts

 

[quote=R_W_B;7660701]That would be part # zero as in never made.
So then now it's your turn to comment on the sequence.

Well I said that as you answered your own question. A "dual fire" ignition is just that when either hole needs lit both plugs get zapped. So in essence there truly is no firing order on that particular engine. Like there is no radiator on a VW Bug. One hole is always firing 45 degrees off. Here is the basics from 8541Hogs link.

So here's the firing order.
Front Bang, rotate 315 degrees - Rear Bang, rotate 405 degrees - Front Bang, rotate 315 degrees, - Rear Bang, etc.
So there it is. The engine sounds like it does because the firing order is irregular, it kind of lopes along, as it has since 1903. And probably will until the next century, if the traditionalists have their way. I hope so.

 

113117021 - now spill it.