Motobecane problem...

Ok, I'm new at the moped game. On the left side of my Motobecane 50 Mobylette, there is a nob with labels, "On," "Off," and "RES." What does said nob do? The nob itself is labeled "fuel," but it didn't do anything notecible when tinkering with it.

Also, could this tinkering have antything to do with the fact that the moped was maxing out at around 22mph today on a flat road? I'm so confused, and don't have a ton fo cash for repairs.

Re: Motobecane problem...

i dont have a motobecanebut this sounds like a fuel tank valve, properly known as a 'petcock'.

Off turns the fuel off at the tank.

"On" allows the tank to drain down to the 'RES' level. (there is still some fuel in the tank but the bike will run out of gas at this point)

The "res' is Reserve. There is probably about 20 ounces of fuel in the tank accessible when 'RES' is selected. When you run out of gas with the "ON" setting, switch to RES and restart the bike.

To check/see if this petcock and it's slow fuel flow is responsible for the slow road speed, remove the fuel line from the carb and drain some fuel into a container . A steady stream of fuel should flow at both the ON and RES settings.

If not, it's a good idea to clean the tank, cap (make sure it vents), fuel lines ... may as well clean that carburetor too and get that entire fuel pathways working properly..

Get yourself a manual ASAP and learn about your bike... might be one available in the "resources" up there at ths top of this page..

Re: Motobecane problem...

here is the manual

but first read freds guide,

good luck If it goes 22mph well, you are in good shape just read freds guide

Re: Motobecane problem...

Keith Hannah /

Good advice from both. Joew is right about your petcock.

There were 3 versions of the mobylette; 20, 25 and 30mph. If you max out at 22, you MIGHT have the 20mph version. Check everything before accepting that though.

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