This has been around for four years or so.

Two Saito 56's at 90 degrees

[youtube]http://www.youtube.com/watch?v=8VJVbaWg994&list=UUdwTxf4mXHbQ31tR3i-aTnw&index=15&feature=plcp[/youtube]


[youtube]http://www.youtube.com/watch?v=FhFziitv4EM&feature=BFa&list=UUdwT xf4mXHbQ31tR3i-aTnw[/youtube]

Now that is cool. Looks like someone wanted a Saito version of the Enya VT-240, except the 240 is twice as big. Very cool that the crankshaft, rods, and crankcase are homemade. I'm drooling.

I found the comment comparing that engine to a "Harley" being corrected amusing. "build a mini harley W/that motor""A harley has not the 90 degree angel bud only 60 dergee. So that's not good".


Wouldn't a version using 180 or 220 pots be awesome?

It also sounds like the cylinders fire opposite, unlike a harley engine that fires both cylinders together... It looks and sounds very smooth. Is there any other information about the engine around, w8ye?

Harleys fire 1 cylinder per revolution, not "together". That's how they could use a single set of points on a non-symetrical cam lobe in the distributor @ 1/2 crank speed to fire both cylinders.

The difference from 45* to 90* would explain the difference in sound.

Actually the Harley fires the rear cylinder then 45 degrees later the front cylinder then about 540 degrees before the rear again.

Maybe your's does, but my '64 Panhead fired 315*- 405*. That = 720*

Front cylinder fires, 315* later, rear cylinder fires, 415* later, front cylinder fires again. Once every revolution, 720* crank rotation.

45* less than 360* (315*) separates the F/R firing order, then 360 + 45* (405*) separates R/F firing order.

45*+ 540*+ 45* = 630* You're missing 90* there somewhere. [X(]

That 90 degrees is there whether or not I wrote it down. This from Kevin Cameron of Cycle World, the reason for the famous Harley lope at idle was that when the rear cylinder was on its intake stroke the air fuel mix turned 90 degrees left after leaving the carb, as the front cylinder began its intake the air fuel mix had to stop abruptly then change directions to the right. The cams could be arranged to make one fire like yours but that was not normal.

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

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

In this link they do reference the XR-750 as a "V Twingle" having a firing sequence of 45*-675*, but the Harley Davidson street "V" Twins" are 315*-405*

http://en.wikipedia.org/wiki/Big-bang_firing_order

BTW: I was never aware that the XR750 ("V Twingle") had a different firing sequence that the Harley Davidson "V Twin".

Sorry about that, the XR had two carbs for that reason because both cylinders would be intake at the same time, partly anyway. Back to Saitos.

Techincally, the (standard) Harley does fire during the same crank rotation when one considers that there is only 305* between the F&R power strokes. The common misconception is the 45* firing sequence.

As for the XR750 45*- 675* sequence? I have read that the long pause between the power cycles aids "hookup" on dirt tracks allowing the rear tire to recover grip between power pulses., much like a large single cylinder.

As well as the induction benefits, an added beneifit of the dual carbs is that it allowed the exhaust ports on both cylinders to be located forward to help somewhat in the rear cylinder cooling. The rearward location of the rear exhaust port contributes emmensely to the rear cylinder running hotter than the front.

Back to Saitos.

The firing sequence of the Saito 90* "V" twin in the clip should be 270*- 450*. The alternative would be 90*- 630*.

Jim, I can't make out whether that thing has one or two carbs, Thanks, Dave

At 0:47 in the top clip you can see dual carbs situated right next to each other W/the throttle arms actuated via a joining link.