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Mec Eur 42/160 Idle Jet for SI Carbs

Idle Jet (42/160); SI Carbs

$7.00
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Mec Eur 42/160 Idle Jet for SI Carbs
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  • Mec Eur 42/160 Idle Jet for SI Carbs
Idle Jet (42/160); SI Carbs

Idle Jet (42/160); SI Carbs

$7.00
Part number 183238

Check dimensions and compatibility before ordering.
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This is the smaller jet that screws in next to the main jet stack. It regulates fuel/air mixture at the bottom 1/3 of the throttle. A combination of the idle jet and the main jet handle the middle 1/3.

If your idle jet is too big or too small, it can create a flat spot in the acceleration. Idle jets have two numbers. The first number is the size of the bore that allows fuel in, and the second is the size that allows air in. Available sizes are: 38/120, 42/160, 45/120, 45/140, 48/160, 50/120, 55/160. So a 45/120 jet would run richer than a 45/140, because the 120 allows less air to pass. To make things more complicated, some vintage Vespas came with plugged idle jets, which have no air hole. These are available in sizes 42 and 50.

Jetting is something that takes trial and error.

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