Spaco

Idle Jet (38/120); SI Carbs

SKU 191884
$7.00
Shipping calculated at checkout.
Description
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. See our blog of jetting instructions for more info.

  • Same day shipping for orders placed before 2PM (CST) M-F
  • 30-day return period
  • Flat-rate shipping for orders shipped to the 48 Contiguous United States.
Since 1989

Supplying parts and accessories for vintage and modern scooters since 1989 – Over Half a Million Served and Counting!

Comprehensive Resource

From wear-and-tear items like tires and oil filters to aftermarket parts from industry-leading brands.

Dealer Focused

With a committed team of dealer-focused sales reps and streamlined pricing and shipping processes, we are dedicated to supporting your business.

Innovative

Our team constantly strives to develop and source the best new products for your scooter.