'77 Motobecane... clutch

Been trying to get my 77 motobecane (50V) going...

What I am refering to as the clutch in this letter is the thing that the belt goes to on the engine. The outer part turns, the middle part stays still. (I say this because I don't truly know if it's a clutch)

When pedaling or rolling downhill... is the clutch supposed to engage at some point to start turning the engine? Because the middle part is not turning on mine. I figured when I got going fast enough it would engage. Or does it not engage until the engine starts running?

Thanks!

--Brewster

Re: '77 Motobecane... clutch

Ron Brown /

Brewster,

It usually won't engage until you operate the compression relief valve on the right handlebar. Then, when the engine is turning, release the lever.

Ron

Re: '77 Motobecane... clutch

Chris Robertson /

If Ron's advice doesn't work, you might need to take apart the clutch and make sure that it is clean. Sometimes rust, dirt, or grease can get in there and cause the starting clutch to slip.

Sand off the shine on the clutch pads and drum with 100 grit sandpaper and clean it with brake parts cleaner until you can't see crud on a clean paper towel when you wipe it.

Most mopeds have two clutches in the same unit --one for starting the engine, and the other for turning the wheels.

Chris.

Re: '77 Motobecane... clutch

Ron Brown /

Chris,

You dispensed that advice so casually. Do you have any idea where I could find a puller that would get me into my Motobecane clutch?

Ron

Re: '77 Motobecane... clutch

Chris Robertson /

Hi Ron:

I'm getting to understand why people say Motobecanes are so hard to work on!

I took it for granted that the clutch would be easy to get at. How is it assembled? Would drilling and then tapping holes to allow using an harmonic balance puller work? I do that sometimes with flywheels...

Chris.

Re: '77 Motobecane... clutch

Ron Brown /

Chris,

It uses one of those pullers with an external thread to screw into the clutch flywheel and a center bolt to press on the crankshaft to pop it off. Like a Briggs and Stratton flywheel puller. I would not want to drill and tap it without knowing what was on the inside.

Ron

Re: '77 Motobecane... clutch

Ray Sanders /

So, when you pedal, the belt turns BOTH Pulleys, but the engine doesn't crank over?

Yes, at some point, the belt is supposed to turn over the engine, and once the engine starts the belt is used to transfer power to the rear wheels. Yes, it is a clutch/variable transmission.

Having a good, tight belt helps. My drive belt was near death, and died over the weekend. I bought a new belt at Autozone for $4.06 after tax, versus $21.95 + Shipping on mopedjunkyard.com. 17/32 x 31.5" long. Now the bike starts after pedaling for about 5 feet.

Weird, and yes... Motobecanes are a royal pain in the ass to fix/work on.

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