Differences between 50V and 50L Motobecanes

When I got started on converting my 1977 50L Moby to a 50V I thought, "How different can they be?"

I found out that they are pretty different:

Front sprocket tooth count (L=44 V=54)

Back Sprocket tooth count (L=13 V=11)

Chain length (approx. L92= V=104)

Belt tension spring (V spring is much stiffer)

Spring retaining clip (V has a longer hook)

Hopefully this will save someone else some time.

Re: Differences between 50V and 50L Motobecanes

I felt like an idiot for not figuring it out, but V stands for Variator. L... does not.

Re: Differences between 50V and 50L Motobecanes

according to the manual from france the forx are different. maybe that is a europe thing

Re: Differences between 50V and 50L Motobecanes

yeah the differences between variater and non variated bikes is big, NO VARIATOR!

Re: Differences between 50V and 50L Motobecanes

Yep, I was hoping I could just pop a variator on and be good to go.

but there was a little more involved

Re: Differences between 50V and 50L Motobecanes

u almost can u only need a, variator, u can use the old gearing but it won't run that well so gearing, the old spring should work too, just use a table vice or somthing to pry it out farther so its more taught. the hook can be bent or removed, or dermiled, and you should get a new belt anywho.

Re: Differences between 50V and 50L Motobecanes

You can switch the rear sprocket on the 50L, I did it on this m1977 model, the chain of course has to be longer

THIS IS BEFORE

See the video after the conversion the moped was able to handle the hill a lot better since the conversion and the clutch being a Dimoby, I did loose to some top speed on the flat but it did move quicker from dead stop.

Re: Differences between 50V and 50L Motobecanes

Fortunately, I had a 50V parts bike sans engine, so the conversion went pretty smooth. . .

Once I was able to get the dimoby off the 50L that is.

Re: Differences between 50V and 50L Motobecanes

Add to that list, the lever on the driven pulley, it's a different shape and the gear engagement gap is much deeper on the 50V version.

Re: Differences between 50V and 50L Motobecanes

i'm planning on rebuilding a couple of these that are engineless. if i'm rebuilding the entire engine and variating it, do i have to worry about any of the mounts being different? are there any differences (other than rigid frame) once i variate them?

Re: Differences between 50V and 50L Motobecanes

the mounts on a 50v frame are the same as a 50l, if thats what you're asking. av7s only mount in two places.... the main bolt that goes thru the flexiblocs, and the bolt on the return spring. its the same whether its variated or not.

one thing i never got was this... ive noticed, like ian posted at the beginning of this thread, that the gearing on a 50l is for higher speeds than the 50v. it seems like you'd want it to be the opposite: the 50l loses low end because of lack of variator, so gear it lower... the 50v has low end to spare cause of the variator, so gear it for higher speeds. why'd they do it the other way around?

Re: Differences between 50V and 50L Motobecanes

anybody?

Re: Differences between 50V and 50L Motobecanes

sorry but i should probably specify but they're actually 40s. lame luggage rack and all. i just wanted to make sure the frames were solid. i haven't rebuilt any of these.

Re: Differences between 50V and 50L Motobecanes

well a 40 is a bit different from a 50, but still as far as i know the engine mounts are in the same places.

40s are pretty coveted, actually... they look kinda cool (opinion i guess), theyre rare, and i'd imagine the lack of suspension in the back would make mounting pipes a bit easier.

Re: Differences between 50V and 50L Motobecanes

wow, time machine! I think the L models were purposefully designed as a cheaper model for the oldies in the US. If you don't have a variator you want to be tuned for top end as opposed to torque else you'd never reach a cruising speed of 30mph.

Re: Differences between 50V and 50L Motobecanes

that seems reverse to me. not tryin to start a fight or anything, i just dont get it.

the variator is what gives mobys their great low end. say you take a variator off a 50v and replace it with a dimoby, but leave the gearing 11:54. You took most of the punch out of the low end by removing the variator, but at least you still have gearing that is more or less for low end. Now, change that gearing to 13:44 (as with 50l) and you have a single speed ped that is geared for top end. doesnt really make sense to me that they would destroy all the low end and then not only do nothing to accomodate that change, but actually make it worse. see what im sayin?

are you saying this is one of the attributes that made them cheaper?

Re: Differences between 50V and 50L Motobecanes

if you variate the motor, you don't have to gear for better low end because you get it via the variator. think of it as accentuating the torque curve to promote a higher top speed, rather than defeating it.

i figured that these were the poor man's moby. i have a maxi n that i'm rebuilding right now. that makes half of the mopeds i've found rigid.

Re: Differences between 50V and 50L Motobecanes

The sprocket gearing is just part of the puzzle, the diameter of the pulleys also affects the gear ratio. That being said the diameter of a fully variated bike is larger than the diameter of the dimoby. I bet the total gearing is prety similar on respective speed models.

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