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Discussion Starter #1
I am just curious why Vee and other motorcycles in general have not switched over to a single throttle body and manifold.

I assume this eliminates balancing problems and allows for injectors to be positioned over the intakes.

It would appear to be both cheaper and better
 

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FORUM GODFATHER.....R.I.P. PAT
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Performance would suffer, especially at high rpm. Harleys have a manifold feeding two cylinders and behave accordingly, making power at low rpm and requiring large displacements. Performance is mostly about air flow and intake manifolds are flow killers.
 

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I think it could work okay if the engines had even firing cycles. (In a vertical twin with 360 degree cranks) but V-Twins tend to have uneven firing cycles. (What would the crank offset be for an even firing 90 degree V-Twin? Would it be really poorly balanced?)

..Tom
 

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Honda NC700x.... What Greywolf said........................
 

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My son's CB250 has a single carb and a manifold. Easy as pie to tune, gutless as all shyte to ride at speed, still vibrates like any other parallel twin. The tuning simplicity is great for a new rider learning how to maintain their own machine but as mentioned the top end performance suffers.
 

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Discussion Starter #6
I like the uneven firing order argument

There are MANY cars making good HP with single throttle body. There may not be room for an adequate sized manifold though
 

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FORUM GODFATHER.....R.I.P. PAT
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Again, the cars are running large displacement, low revving engines compared to motorcycles. Harleys have uneven firing pulses but run off an intake manifold. I don't think any bike runs an exhaust manifold. Manifolds rob power by limiting air flow, the higher the rpms the greater the limitation. Multiple throttle bodies are touted as a hot setup for high performance cars. What is the Advantage of Multiple Throttle bodies? is a short thread on a BMW car site.
 

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Oddly enough, until recient years most single pin V45-52* engines used a dual fire ignition (single firing pulse simultaneously to both cylinders). Since the Pistons were in different strokes, this resulted in "wasted spark" for one cylinder.
 
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