Firing order, etc., for VFR800Fi (180° crank)

My spreadsheet for the firing order of the VFR800Fi is below. For comparison, I've included one for the V4 Ducati. I originally had the wrong locations for the cylinders, which threw everything else off. I corrected the error. Thanks, Grum.

There are two critical differences between the Ducati and the Honda. One is the firing order for the cylinders on the same side. In a 90-degree V4 whose pair of pistons on each side share a crankpin, there are only two possible firing orders for that pair. One is 90--630, and the other is 270--450. The firing order of the VFR is 270--450. The firing order of the Ducati is 90--630. The other critical difference is the crank offset. The VFR crank has a 180 degree offset. The Ducati crank has a 70 degree offset.

 

VFR doesn't look right! Firing order is correct 1-3-2-4 But....
No.3 power stroke should commence at 180deg.
No. 2 power stroke should commence at 450deg.
No. 4 power stroke should commence at 630deg.
Then another 90deg back to No. 1 equals the 720deg complete cycle.

 

Yes, you are right about the locations. I've fixed that, but the new locations change the firings. Fixing that now. Thanks.

 

I made the corrections in the original post. Have a look.

 

I found a source that claims the "firing interval" is
1 at zero degrees, 3 at 180 degrees, 2 at 270 degrees, and 4 at 450 degrees. He says this below the video, but you have to go to youtube to see it. I just checked the service manual. I think your info is correct.

 

The figures I gave you were the additive firing angles over 720deg of a complete cycle.

You can also just mention the firing angle differences. Like 180 from 1 to 3, 270 from 3 to 2, 180 from 2 to 4, and 90 from 4 to 1. That all equals 720deg as well!

Video is not right. Longest duration should be between 3 to 2. Shortest duration should be 4 back to 1.

Your Spreedsheet looks correct now for the VFR.

 

I had a chat with the author of the video. He said his numbers don't match ours because he has his own numbering system for the cylinders, where his #1 cylinder is the front right.

 

Makes No Sense, his numbering system is correct, bit hard to see the cylinder numbers on the video but they are there - top of the video equals 1 and 3 (being the Rear) bottom equals 2 and 4 (being the Front).
But, by his graphic, the diagonal path from the Rear cylinders to the Front cylinder (3 to 2) Should be the Longest duration. And, the end of the sequence back to the start (4 back to 1) Should be the Shortest duration. He appears to have this reversed!

 

Like this from the service manual:

 

Moser (the author of the youtube video) says he isn't describing a VFR, just a hypothetical V4 that differs from a VFR only in the numbering of its cylinders. He has his engine turned 180 degrees as if you were looking at it from the front, not as if you were sitting on the bike looking down. At the moment, Grum and I figure if that's the only difference from a VFR, his claim that the "Firing interval is...

1 at zero degrees, 3 at 180 degrees, 2 at 270 degrees, 4 at 450 degrees" is still wrong.

His "firing interval" would still have to be the same as the "firing interval" of a VFR:

1 at zero degrees, 3 at 180 degrees, 2 at 450 degrees, 4 at 630 degrees.

 

Here's a spreadsheet for Moser's engine. Is this possible with a 180 degree, forward-rotating crank?



Edit: According to this wikipedia page, the 1986 VFR had the firing order of Moser's engine. Is the Wikipedia page wrong? Not really. It just lists the VFR twice, once starting its firing order with 180-90, and again starting with 180-270. But, that whole page is screwed up because it's supposed to be a list of big-bang engines, and half of them are not. The stock VFR certainly isn't. It only has a 90 degree overlap of 2 power strokes. If you want to see a real big bang, look at the VFR built by Langdon.

 

Think you should have a good look at this. Early VFR's had a 360deg crank.!

 

Moser's engine and the VFR both go:

180 - 90 - 180 - 270 -180 - 90 -180 - 270 ...or
...............-180 - 270 - 180 - 90 - 180 - 270 - 180 - 90...

depending on where you start counting.

The real difference is that different cylinders are firing:

Moser: ..RF180 - LF90 - RR180 - LR270 - RF180 - LF90...
The VFR engine.............: LR180 - RR270 - LF180 - RF90 - LR180 - RR270...

It may seem impossible that the Moser engine fires at 0, 180, 270, and 450 degrees and the VFR fires at 0, 180, 450, and 630 degrees, but I think it's not. It all depends on where you start counting the fires. If you start counting, as Moser does in the examples above, at 0 degrees with a fire whose 180 degree interval is followed by a fire with a 90 degree interval, then you get Moser's 0, 180. 270, 450 firing pattern. If you start counting, as Honda does, at 0 degrees with a fire whose 180 degree interval is followed by a fire with a 270 degree interval, like this: 180 - 270 - 180 - 90...then you get Honda's 0, 180, 450, 630 firing pattern. But that's trivial. The more interesting question is what would you have to do to a VFR to make it fire the same cylinders, at the same time, as Moser's engine? Different cams? I don't think it would be as simple as the cam mod discussed in the post about making a big bang.

 

Those weren't VFRs ... those Interceptors were "VF"s. The earliest VFR was the 1986 Rc24, and that has a 180 crank.