Main Jet #78 for SHA/SHB Carbs for Scooters & Mopeds
ITEM# TT-25793
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Description
Main Jet #78 for Vespa Small Frame Scooters and Mopeds
This #78 main jet suits Vespa small frame scooters running 16mm and 19mm carburetors, and it also works with PHBG models. The jet controls how much fuel moves through the carburetor, so it plays a key role in the fuel supply. You can find it alongside other scooter carburetors & jets. When it is matched to your setup, it can help the engine respond better at the throttle and run more efficiently.
How Main Jets Work
Main jets sit in the fuel delivery path of a scooter. Fuel flows through the jet once the needle is raised, which sets the air-to-fuel ratio the engine receives. Sizes run from 37 to 88, so you can adjust the tuning to suit your riding style and the conditions you ride in.
Fitting and Tuning
Swapping the main jet means taking the carburetor off, and getting the setting right may take a few attempts. Reading up on jetting methods before you start is a good idea so you can set things correctly. Changing the jet can noticeably alter how the engine performs, particularly when conditions shift.
Specifications
- Size: 78
- Position: Main jet
- Fits: Small Frame Vespa scooters with SHA/SHB carbs (16mm and 19mm), also PHBG carbs
Fitment
Fits:
- Small Frame Vespa (16mm and 19mm SHA/SHB carbs)
- Small Frame Vespa with PHBG carbs
How to choose: Install it where your carburetor specifies a #78 main jet. Main jets range from 37 to 88, so read the size stamped on your current jet before you order.
Shop more: Scooter Carburetors & Jets · Scooter Parts
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