Because the slow rate of combustion of natural gas, it's easy to produce the phenomenon of cyclic variations, when taking lean burn technology, the cyclic variations will be increased.

由于天然气的燃烧速率较慢，易产生燃烧循环变动现象，采用稀燃技术时会加剧燃烧循环变动。

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The intake port and combustion chamber of CA6102 SI engine were improved aiming at its slow burn-rate and big cyclic variability in this paper.

本文针对CA6102发动机燃烧慢、循环变动率偏大等问题，对进气道和燃烧室进行了改进。

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The combustion is slow and rich, using just enough oxygen to bust apart the diesel molecules into hydrogen and carbon monoxide without burning off the diesel entirely.

FORBES: Clearing the Air

But if, as many predict, the shift from cars with conventional combustion engines to electric cars is set to remain slow for years yet, there is another, less visible, electric motoring revolution taking place.

BBC: Electric motoring: a quiet revolution