Speed

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tony.mon
Posts: 16022
Joined: Wed Jul 25, 2007 10:46 pm
Location: Norf Kent

Re: Speed

Post by tony.mon »

The Yam doesn't quite fire in pairs- I don't have the exact firing sequence and degrees of the Yam to hand but it fires either two or three pulses in quick succession then the other two or one later, hence a twin-like sound.

If it genuinely fired say, cylinders 1 and 3 at the same time, then 180 crankshaft degrees later fired 2 and 4 simultaneously, that'd be interesting, and WOULD sound like a vee twin, or at least a 180 degree crank parallel twin.

But of course the Storm doesn't have equally-spaced firing either; to maintain good primary and secondary balance it has to fire 0-450 and back to the first cylinder 270 degrees later.

So it'll fire one cylinder; then the other after 270 degrees, then a long pause (while the tyre regains traction) of 450 degrees, etc, etc.

Bear in mind that because it's a four-stroke the crankshaft will turn two complete revolutions for a full cycle of firing, i.e. 720 degrees.

What would be really, truly interesting is if the engine could be persuaded to run properly with the timing 180 degrees out, as it gets to try occasionally when people don't get the cam timing set up properly.
Then it would run 0- 90-630, so would have two power pulses almost together, then a LOOOOONNG pause of 630 degrees of crankshaft rotation to recover traction before all hell breaks loose again.

It would vibrate, but run similar to a 1 litre single.....gotta be fun, surely.........

But it would need separate exhausts and a separate airbox for each carb to make it runs ok at higher revs, and with two airboxes you probably only have enough space for 5-10 litres of fuel, and it's already below par on that front.

BTW, have had a wee drinky or to, so feel free to correct my timing quotes from memory to accurate ones :beer:
Last edited by tony.mon on Thu Feb 03, 2011 6:29 pm, edited 1 time in total.
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alec
Posts: 681
Joined: Fri Jan 21, 2011 3:36 pm
Location: Aylesford, Kent

Re: Speed

Post by alec »

tony.mon wrote:The Yam doesn't quite fire in pairs- I don't have the exact firing sequence and degrees of the Yam to hand but it fires either two or three pules in quick succession then the other two or one later, hence a twin-like sound.

If it genuinely fired say, cylinders 1 and 3 at the same time, then 180 crankshaft degrees later fired 2 and 4 simultaneously, that'd be interesting, and WOULD sound like a vee twin, or at least a 180 degree crank parallel twin.

But of course the Storm doesn't have equally-spaced firing either; to maintain good primary and secondary balance it has to fire 0-450 and back to the first cylinder 270 degrees later.

So it'll fire one cylinder; then the other after 270 degrees, then a long pause (while the tyre regains traction) of 450 degrees, etc, etc.

Bear in mind that because it's a four-stroke the crankshaft will turn two complete revolutions for a full cycle of firing, i.e. 720 degrees.

What would be really, truly interesting is if the engine could be persuaded to run properly with the timing 180 degrees out, as it gets to try occasionally when people don't get the cam timing set up properly.
Then it would run 0- 90-630, so would have two power pulses almost together, then a LOOOOONNG pause of 630 degrees of crankshaft rotation to recover traction before all hell breaks loose again.

It would vibrate, but run similar to a 1 litre single.....gotta be fun, surely.........

But it would need separate exhausts and a separate airbox for each carb to make it runs ok at higher revs, and with two airboxes you probably only have enough space for 5-10 litres of fuel, and it's already below par on that front.

BTW, have had a wee drinky or to, so feel free to correct my timing quotes from memory to accurate ones :beer:
What the F**k does all this mean lol
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storminateacup
Posts: 715
Joined: Wed Jun 20, 2007 3:38 pm
Location: Maldon

Re: Speed

Post by storminateacup »

alec wrote:
tony.mon wrote:The Yam doesn't quite fire in pairs- I don't have the exact firing sequence and degrees of the Yam to hand but it fires either two or three pules in quick succession then the other two or one later, hence a twin-like sound.

If it genuinely fired say, cylinders 1 and 3 at the same time, then 180 crankshaft degrees later fired 2 and 4 simultaneously, that'd be interesting, and WOULD sound like a vee twin, or at least a 180 degree crank parallel twin.

But of course the Storm doesn't have equally-spaced firing either; to maintain good primary and secondary balance it has to fire 0-450 and back to the first cylinder 270 degrees later.

So it'll fire one cylinder; then the other after 270 degrees, then a long pause (while the tyre regains traction) of 450 degrees, etc, etc.

Bear in mind that because it's a four-stroke the crankshaft will turn two complete revolutions for a full cycle of firing, i.e. 720 degrees.

What would be really, truly interesting is if the engine could be persuaded to run properly with the timing 180 degrees out, as it gets to try occasionally when people don't get the cam timing set up properly.
Then it would run 0- 90-630, so would have two power pulses almost together, then a LOOOOONNG pause of 630 degrees of crankshaft rotation to recover traction before all hell breaks loose again.

It would vibrate, but run similar to a 1 litre single.....gotta be fun, surely.........

But it would need separate exhausts and a separate airbox for each carb to make it runs ok at higher revs, and with two airboxes you probably only have enough space for 5-10 litres of fuel, and it's already below par on that front.

BTW, have had a wee drinky or to, so feel free to correct my timing quotes from memory to accurate ones :beer:
What the F**k does all this mean lol
Didn't you read what he said, he's pissed and hasn't a clue what he's talking about it's that bloody cider. :beer:
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