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Stupid suggestion: New camshafts to have cyls fire together?

  • Thread starter Thread starter Skyboy8950
  • Start date Start date
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Skyboy8950

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I'm wondering, since the spark plugs already fire during the exhaust stroke, if a modified cam could make two cyls fire together? That would make for a completely different sound of the exhaust, more like a Harley. I'm wondering what would prevent someone doing this? I certainly don't want to do it, but it seems as though new camshafts would be all it takes.

Just an idea. Interested in sparking a conversation.
 
I don't think it would be nearly as smooth as it is now and although it doesn't sound terribly crazy, it would probably have a few crazy little quirks that would have to be run through.
 
Skyboy8950 said:
I'm wondering, since the spark plugs already fire during the exhaust stroke, if a modified cam could make two cyls fire together? That would make for a completely different sound of the exhaust, more like a Harley. I'm wondering what would prevent someone doing this? I certainly don't want to do it, but it seems as though new camshafts would be all it takes.

Just an idea. Interested in sparking a conversation.
Click to expand...
it has been done mate. kawasaki made the big bang engine for their motogp bike but it never made production, too expensive and unreliable.
will try and find the youtube vid. sounds absolutely awesome!
 
Big bang cams for the 1000 appear every now and then. Never seen one in action but they're around. (I've got an idea the Aussies were in to this at one time - maybe someone from downunder will confirm).
 
Man, if there were cams around, I might put them in. That would be awesome! Thanks for indulging my silly question.
 
If you want to sound like a harely, just pull number one and two spark plug wires and ride around at 1,200 rpm.
Oh, better pull the mufflers off too.
 
a.) i would think this would effect cylinder scavenging and throw the a/f way off. even further, possible high pressure on the backside of the exhaust valve from opposing cylinders. more or less a tuning nightmare.

b.) how would you modify ignition timing if you chose to go this route, or would it be left as is?

c.) increased internal harmonics would play havoc on fasteners and vital structural components, let alone bearings.

from a theoretical standpoint, i dont see how this would be in anyway more efficient as the internal combustion engine relies on the spark event/combustion to push the cylinder down. 360* of rotation. also, altering the valve events in such a manner would relieve some of the cylinder pressure needed for proper burn, which leads me back to a skewed a/f. valve timing over ignition timing is HUGE.


but for sound, maybe. i dont see the bike getting out of its own way when configured in this fashion.



but, i dont know these bikes too well yet. i may be way off base. just a motorhead rattling off.
 
there was a aussie company that made these cams called big bang cams, might still be around. It has been talked about on here before, should come up in a search.
 
We did it before Kawasaki did, with a Honda 750 dragbike. It didn't make anymore power, so it was abandoned.

Jay
 
Might want to read up on the new Yamaha R1. Their solution works and while I haven't heard one run myself those that have are impressed with the sound. I think Mr. Rossi is impressed with the performance. Involves a staggered crank, I doubt the technology is backward compatible.
 
isleoman said:
Might want to read up on the new Yamaha R1. Their solution works and while I haven't heard one run myself those that have are impressed with the sound. I think Mr. Rossi is impressed with the performance. Involves a staggered crank, I doubt the technology is backward compatible.
Click to expand...

The new R1 and those motoGP bikes don't fire the cylinders in pairs like being discussed here. Those bikes use a special crankshaft, to go with the camshafts, and stagger the firing order in a special way. Check this video for more info... http://www.youtube.com/watch?v=UvTX...amaha-r1-crosspl.html&feature=player_embedded

The main advantage to this type of engine is to optimize traction in big HP applications, or where traction is limited. Seems like a silly idea for a GS bike unless maybe for ice racing.;)
 
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Just to clarify: I don't plan to do it. I just thought it was an interesting idea I had (an apparently others have had it too).

Thanks, good discussion.
 
Skyboy8950 said:
Just to clarify: I don't plan to do it. I just thought it was an interesting idea I had (an apparently others have had it too).

Thanks, good discussion.
Click to expand...

Skyboy, I for one understood that this was a discussion of possibilities.

So Please don't try to put that R1 crank in your bike.
 
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