Main Jet #103 for SI Carbs for Scooters & Mopeds
ITEM# TT-25699
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Description
Main Jet #103 for SI Carburetors in Scooters and Mopeds
The Main Jet #103 is a precision part used to tune SI carburetors on scooters and mopeds. This small, cone-shaped piece regulates fuel delivery from the main jet stack. It suits a range of engines and is commonly chosen for vintage Vespas, which generally call for jets within the 85-116 range. You can browse more carburetor parts and jets that play a direct role in how an engine runs and how much fuel it uses.
How It Works and What It Does
This jet sets how much fuel reaches the combustion chamber. Higher numbers pass more fuel, so the size you choose has a direct effect on flow. Many riders try several sizes to find the best setup, particularly on modified engines that often need larger jets to get enough fuel through.
Fitting and Tuning
To swap it in, take out the current jet and seat the new one in the same spot. Basic hand tools are enough for the job. Dialing in the right size often takes some testing, so plan on trying a few options before settling on the one that performs best.
Specifications
- Size: 103
- Position: Main jet stack
- Fits: SI carburetors for scooters and mopeds (main jet stack, #103 size)
Compatibility
Fits:
- SI carburetors (main jet stack position, size 103)
Choosing a size: Match the jetting to your engine. Most vintage Vespas run in the 85-116 range, and finding the ideal size takes trial and error.
Browse further: Scooter Carburetors & Jets · Scooter Parts
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