Flashback wrote:
I think your reasoning is sound texasscott, my only question is does the r* fire the wasted spark? In todays world the signal being generated once every 360 doesn't mean that both coils get energized at the same time, I figure the ECM chooses which coil gets the signal.. I don't see the purpose for putting 2 coils in a bike if you run a dual fire ignition..like you said in your first/previous post, they did it cause it was simple back when the signal was generated with ignition points, now days with all the electronics it seems as tho it would be just as easy to do the single fire..In the old days, they used to have dual point setups that would change a dual fire to single fire...

And thats all I know about that...and still didn't come up with a definitive answer....

But I can promise ya that old 350 was triple fire....

The GM ignition will definitly make you hurt yourself. Been there done that more times than I can remember.

The ECM does in fact choose which coil gets the signal but because our engine doesn't have a cam angle/position sensor to tell the ECM when the piston is on compression it fires each coil/piston pair every time that piston is up and gets it right half the time. Simplicity and lower cost.

Scott B.

Pfluegerak wrote:
IMO you've got the cycle theory correct, just don't count the last spark on the same cyliner you started with. The third spark your counting is the beginning of another full cycle.
So Harley's would have 2 pulses per 2 crank revolutions.
I don't think our coils fire on the exhaust stroke, just the compression stroke. For ours, a coil would produce 1 pulse per 2 crank revolutions. I guess I need to test this per Curt's instruction. Defibrillator?

That's just it our's does fire on the exhaust stroke. Think about it a minute - how does the computer know the piston is on the compression stroke? Since there is no signal from the cam telling the computer when the compression stroke is, the computer has to fire on every stroke in order to catch the piston on compression otherwise it wouldn't start.

I used the 3 pulse because they both add up to 720 degrees. If you compare 2 pulses then the Harley, starting with #1, has 2 in 405 degrees and the Road Star has, in one coil, 2 in 360 degrees.

Scott B.

As Curt said there are two timing marks on the pickup rotor, one for each cylinder. The pickup coil senses the position of the rotor and sends a signal to the ignitor which fires the appropriate coil.

Each cylinder only fires once per cycle ... on the compression stroke.

Doc

Thanks Doc if I have to prove it when I get my front end all wired back up I will take the right front and rear plugs out and tape them together. Then I will ground them with a cable and crank the bike while I make a video of it. With both plugs side by side I should be able to capture the spark and then there will be no question.

Curt,

how to figure out if it fires on a cyclinder in both the compression and exhaust stroke? besides the defibrillator method.

DocShadow wrote:
As Curt said there are two timing marks on the pickup rotor, one for each cylinder. The pickup coil senses the position of the rotor and sends a signal to the ignitor which fires the appropriate coil.

Each cylinder only fires once per cycle ... on the compression stroke.

Doc

If that is indeed the case, then why does Agpilot's tach that he ordered for a twin fire bike work??? I just keep getting confuseder and confuseder

Cause somebody is wrong or he got shipped the wrong tach from what he ordered. Ether way I am going to find out for sure. I can't believe that Yamaha has designed the R* to fire 4 plus every stroke. Also to finally put this thing to rest.

The tach I bought wired right up with no problems or adapter. I did not state the type I wanted just clicked on buy it now, because I assumed the R* was a dual fire. It was on sale for $47.95 . I noticed thay have almost doubled the price now... But here is what they say.


This listing is for a Mini Tachometer that features a white face and reads to 8000 RPM. It has a stainless steel housing and is designed for 2 cylinder 4 stroke motorcycles. It works with dual-fire ignition systems, but will work with most newer bikes if a tach adapter is added for a single-fire ignition. Buyer must verify which type of system their application has. The handlebar mount's 2-piece design mounts directly to the handlebar with no secondary mounting system needed. It will fit on 1" bars only and requires 2" of space on the bars.


I repeat I used no tach adapter.... I don't know what else to say..But don't get me into this discussion because I don't have a clue... Butch P.S It could be the way I wired it. Or???????

That may be where my difference in definition is Curt. I am thinking that dual fire is when each cylinder fires on every revolution as opposed to your car which fires each cylinder once every other revolution. Since the Road Star has a coil for each cylinder it's not going to fire all 4 plugs at once just the 2 in the cylinder that is approaching TDC whether that TDC is exhaust or compression doesn't matter.

If firing twice during the 4 cycles of a cylinder isn't dual fire then I apologize for my mistake.

Ride safe.

Scott B.

When I ordered my Mini-Tach last year I was told by the salesman I needed the single-fire model for the Yamaha. He confirmed dual-fires are for the H-D's. I got the single-fire and it works fine. What's the problem here?