Main Jet (#109) for SI Carb for Scooters & Mopeds
ITEM# TT-26464
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Description
Main Jet (#109) for SI Carburetors in Scooters and Mopeds
This cone-shaped piece sits at the bottom of the main jet stack inside scooter and moped carburetors. Its job is to meter fuel flow, and it is available in sizes from 82 to 165. Vintage Vespas generally run jets between 85 and 116, while engines that have been modified for more performance may call for larger jets to supply more fuel. If you are browsing for other options, see our scooter carburetors & jets range.
How the Main Jet Works
The main jet sets how much fuel gets mixed with incoming air in the carburetor, which has a direct effect on how the engine runs. Many riders try a few different sizes before settling on the one that suits them best. Whether you are running a stock setup or tuning for extra power, picking the right jet size is key to getting fuel delivered correctly.
Signs It May Be Time to Change the Main Jet
Take a look at the main jet whenever you are tuning the engine or if the scooter or moped is running poorly. If the machine has been modified or seems to be short on fuel, moving to a larger jet could be needed. Checking it regularly helps confirm that the engine is getting the right amount of fuel.
Specifications
- Size: #109
- Position: Bottom of main jet stack
- Fits: SI carburetors for scooters and mopeds, #109 main jet
Fitment
How to choose: Pick the jet whose number matches what your carburetor needs. Sizes run from 82 to 165, and most vintage Vespas use 85 to 116.
Shop more: Scooter Carburetors & Jets · Scooter Parts
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