Main Jet #125, SI Carbs for Scooters & Mopeds
ITEM# TT-26286
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Description
Main Jet #125 for SI Carburetors in Scooters and Mopeds
The #125 Main Jet is made for large-frame SI carburetors used on many scooters and mopeds. It controls how much fuel reaches the engine, so it has a direct effect on performance and efficiency. You can find it among our carburetor parts and jets for scooters. On vintage Vespas, jets usually fall between 85 and 116, while modified engines often need larger jets to supply more fuel.
How It Works and Its Build
This jet is a small, cone-shaped piece that sits at the bottom of the main jet assembly. It sets the fuel mixture going into the engine, which matters for good running. A higher jet number lets more fuel through, something that may be needed after performance work. Getting the jetting right is essential when you tune the fuel system, particularly after engine upgrades or adjustments.
Signs It May Be Time to Swap the Main Jet
Think about changing the main jet if the scooter starts to lose power or if the engine has been modified. Finding the right jetting often takes some trial and error, since each setup is different. For guidance on reaching the best fuel mixture for your scooter or moped, look through available jetting instructions.
Specifications
- Size: #125
- Position: Bottom of main jet stack
- Fits: Large frame SI carburetors (main jet stack, #125 size)
Fitment
How to choose: Install a #125 main jet only when your tuning requires that size. Jet numbers run from 82 to 165, and a bigger number allows more fuel to flow.
Shop more: Scooter Carburetors & Jets · Scooter Parts
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