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Older models such as the Honda C50 used a simple centrifugal governor as part of the transmission , which progressively and severely advanced the ignition as speed rose past a set point , causing engine power to fall off rapidly at higher rpm and road speed , but maintaining the low - and moderate-speed hill climbing ability of the unrestricted version .
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Please list all entity words in the text that fit the category. Output format is "word1, word2". 
Option: location, person, organization 
Text: {0} 
Answer:
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