History
Most US 50V Mobylettes use the AV7 two-stroke with a variator (continuously variable transmission) — not a scooter, but not a single-speed Puch either. The base 50 model used a single-speed dimoby transmission; the 50V added the belt variator that defines most US tuning culture. Stock exhaust and variator weights often cap RPM before jetting enters the conversation.
Quintessentially French: charming, quirky, and a cult parts scene. Motobécane built millions of Mobylettes for domestic commuters; US imports skew toward late 1970s and early 1980s step-through frames with painted steel tanks. Petcock leaks and tank rust are common on barn finds.
Moby people are loyal for a reason. The bikes are light, start easily when the carb and coil are fresh, and look like nothing else on the road. Restoration threads obsess over correct decals, Gurtner rebuilds, and finding a tank that is not pinholed.
First mods most owners consider: a performance exhaust and a clean fuel system. Do both before you chase jetting — a restricted exhaust will fool you into thinking the carb is the problem.
Quick specs
| Engine | AV7 (piston-port) |
| Transmission | 50V = variator · 50 = dimoby single-speed |
| Carb | Gurtner (Encarwi on some) |
| Notable issues | Tank rust, petcock leaks |
Buying & ownership
When shopping a used Motobécane 50V (Moby), run a warm compression check against a known-good bike, confirm the engine turns freely, inspect frame rust (seat tube, down tube, dropouts), verify title and VIN match, and take a test ride for clutch grab and idle stability. Budget a carb clean, fresh plug, fuel lines, and final-drive service on any “runs good” listing.
Use the full buying guide checklist before you pay, and confirm legal class in your state via US moped laws.
Related on MopedMasters
- All 25 classic mopeds — compare platforms
- Manuals & PDFs — factory literature when available
- Guides hub — jetting, porting, maintenance
- Tuning calculators — port timing, intake, pipe, oil mix
- Maintenance hub — carb, oil, storage basics
FAQ
- Is this a moped or a scooter?
- MopedMasters focuses on pedal-capable / classic moped platforms with chain or geared drive — not modern CVT scooters. See moped vs scooter.
- Where do I start if I just bought one?
- Fresh fuel, plug, air filter, chain slack, and a careful first ride. Then work through the maintenance hub before performance parts.
- Can I use the online calculators on this bike?
- Yes for 2-stroke singles — port timing, intake length, pipe layout, and premix all apply. Start at the tools hub.
Three build paths (mild → wild) → Jetting guide Manuals & PDFs →