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A lot of the difference in how a bike responds to off-throttle has to do with the compression ratio of the particular engine, the size of the engine, and flywheel weight. A new BMW twin with approx 600cc displacement per cylinder and over 12:1 compression decellerates with the throttle closed like you threw out the anchor, especially since the BMW fuel injection shuts off on closed throttle until the engine slows to approx 2000rpm. By comparison, the Bonneville twin is very well mannered.

Think of your engine with the throttle closed at 7000rpm as a giant compressor, which the forward inertia of your bike continues to turn over. Downshift a gear and you're turning the 'compressor' faster, therefore more engine braking.

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