Main Jet #120, SI Carbs for Scooters & Mopeds
ITEM# TT-26373
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Description
Main Jet #120 for SI Carbs in Scooters and Mopeds
The Main Jet #120 is an essential tuning part for SI carburetors used in many scooters and mopeds. This small, cone-shaped piece sits at the bottom of the main jet and governs how much fuel passes through, which affects how well the engine runs. If your engine setup changes, this is one of the carburetor parts and jets for scooters you might need to adjust.
What Main Jets Do
Main jets are sold in a range of sizes, usually from 82 to 165. Vintage Vespas generally call for jets between 85 and 116, while engines built for more power often need larger sizes to supply the extra fuel they burn. Picking the right size matters for getting the correct fuel-to-air ratio, which keeps your scooter or moped running smoothly and efficiently.
Deciding When to Swap the Main Jet
You may need a different main jet after modifying your engine for more performance, or if you notice poor acceleration or higher fuel use. Tuning a jet usually takes some experimenting, so expect to make a few changes before you land on the setting that works best. For help with jetting, look for guides that explain how to choose the right size.
Specifications
- Size: 120
- Position: Main jet
- Fits: SI carburetors (large frame carbs) with a main jet stack, size #120
Fitment
How to choose: Check the number stamped on the jet and make sure it matches the size your engine calls for. This listing is for size 120. Most vintage Vespas use a size within the 85-116 range.
Shop more: Scooter Carburetors & Jets · Scooter Parts
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