Restoring a 1978 Motobecane 50V

Thought you all may be interested in seeing my restoration efforts on my 78 Mobylette. My neighbor gave me this moped as she didn't know what to do with it. The bike had been sitting for the last 15 years in her garage and was covered with sawdust, cobwebs and lots of surface rust. The speedo cable was busted and the speedo was removed and bungee corded to the seat. No idea if it ran or not so I brought it out into the daylight for the first time in mid October of 2022.

Here is what it looked like first in her garage and then outside. Pretty rough but I could see the potential for a restoration. I am retired so I have plenty of time to work on it. Also, I have been a motorcycle rider most of my life starting on a Rupp mini bike back in the 60's. I've owned street bikes and dirt bikes so I know how to work on motorcycles.

Of course the tank was empty and rusty but surprisingly not horrible. After a washdown and overall inspection, I found everything the bike came with from the factory to be present. The engine turned over and a thumb on the sparkplug hole proved some compression. Of course there was no spark, no surprise there. But mechanically the bike looked in very good shape.

After photographing every possible angle I could think of for reference, I decided to just tear the bike down for a restoration. Bagging and marking parts, testing electrical components, and cleaning the tank were first on the list. Took a week of washing out, adding simple green, washing again and filling with Evaporust for several days all the while using at least a hundred BB gun BBs and agitating the frame like crazy, finally it cleaned up well with no leaks or debris present. I then soaked down the interior of the tank with WD40 to keep it from surface rusting till it's time for the gasoline mix.

The lower part of the frame where the kick stand mounts was heavily encrusted with oil and road dirt. I got a little too ambitious and used Gunk engine degreaser on that area which not only removed the filth but took some of the paint with it. So glad I didn't spray that stuff anywhere else.

Overall the paint was in excellent shape and I was not planning on a repaint so touchup will be in order. I am planning on rebuilding the engine and have ordered the parts.

I have started reassembly and the difference from start till now is striking, so stay tuned if interested....

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Re: Restoring a 1978 Motobecane 50V

I am! I have a yellow one w/ small seat.

Re: Restoring a 1978 Motobecane 50V

Bob Chesarek /

Hey Ryan,

A few more photos of the teardown and clean up of parts. I will not be using the stock Gurtner carb and have purchased a Dellorto SHA 15 and the new manifold. The speedo drive unit was trashed and frozen solid and the speedo was stuck. A new drive was purchased and the speedo taken apart and cleaned and after a good number of days soaking the lower half in Acetone and then using Breakfree CLP, it spins freely now. I cleaned all the carbon out of the muffler as well as a mud wasp nest in the tail pipe and surprisingly the chrome polished up like new. All the cables will be replaced as well as a new Variator, drive belt, tires and tubes.

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Re: Restoring a 1978 Motobecane 50V

mine was in better condition, kind of. what did you pay for it?

Re: Restoring a 1978 Motobecane 50V

> Ryan Sadler wrote:

> -------------------------------------------------------

> mine was in better condition, kind of. what did you pay for it?

The second thing he wrote :

"> Bob Chesarek wrote:

> -------------------------------------------------------

> My neighbor gave me this moped as she didn't know what to

> do with it. " (edited)

Re: Restoring a 1978 Motobecane 50V

woops! I was speed reading.

Re: Restoring a 1978 Motobecane 50V

> Ryan Sadler wrote:

> -------------------------------------------------------

> woops! I was speed reading.

And his is variated unlike yours.

Re: Restoring a 1978 Motobecane 50V

damn

Re: Restoring a 1978 Motobecane 50V

Bob Chesarek /

Spent a few weeks on degreasing, rust removal, cleaning and polishing chrome, touching up paint and painting some parts that were scratched up. I painted the center stand silver to brighten it up a bit. Boxes full of bagged and tagged parts to go over.

Having the same problem a lot of you have had removing the fly wheel. Since the engine is off the bike, there really isn't any way to hold it still. I have a 1/2" breaker bar with a 3/8" reducer that I tried to use along with the hose clamp around the fly wheel and a block of wood. No luck. Gonna see if a neighbor has a 3/8" impact driver and that along with heat on the nut and penetrate oil will get the job done.

The table full of cleaned parts is in my downstairs game room which we don't use any more. It's a great place to keep finished parts out of harms way. The tool box covers look really bad, lots of pits so I may end up painting them. The fender braces, wheels, package rack, front fender rods and the handlebars cleaned up much better.

I polished the stainless front fender on the buffing wheel and it looks like new.

The forks and front wheel are back on the bike as I am into reassembly this week.

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Re: Restoring a 1978 Motobecane 50V

Bob Chesarek /

A little preview of coming attractions ;-)

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Re: Restoring a 1978 Motobecane 50V

Mike McScoutington /

Don’t forget the Novi nut is reverse threaded.

Re: Restoring a 1978 Motobecane 50V

Bob Chesarek /

Thank you Mike, so that's why it wouldn't budge ;-)) Just kidding. I have downloaded the parts and maintenance manuals for the bike as well as watched a hundred YouTube videos so I have seen a lot of the problems associated with the Moby. I will still have questions as I get into the engine rebuild and testing the coil and other parts.

I appreciate any helpful hints or tips you may have. Thanks again, Bob

Re: Restoring a 1978 Motobecane 50V

Looking fabulous , Bob . ;)

Re: Restoring a 1978 Motobecane 50V

Mike McScoutington /

First off, it looks like you are doing some great work. Secondly, are you using a piston stop or just a strap wrench? I’ve been able to remove some stuck ass magnetos with the motor off using a piston stop and my fat ass to hold the motor in place. You could also try pulling the jug and cutting some pieces of wood to brace under the piston. You can cut them long so you can use those to hold things down while you work it.

Note: supporting from the under side puts a lot of strain on the piston skirt. Not ideal, but also an option.

Re: Restoring a 1978 Motobecane 50V

Bob Chesarek /

Thanks much PD!

Re: Restoring a 1978 Motobecane 50V

Bob Chesarek /

From what I have read, I am nervous about putting that much stress/force on the piston, pin bearings and crank. If I can't get it loose with an impact gun, I will have to try one of your suggested methods. Thank you for the message Mike and the complement on the restoration.

Once I get it apart, I can access the moving parts and see if they just need cleaned or replaced.

Re: Restoring a 1978 Motobecane 50V

Mike McScoutington /

For what it’s worth in 2 years playing with these things, including some time as a mechanic at 1977 Mopeds back in the day, I’ve only see a piston stop ruin someone’s day like once. Rope in the spark plug hole as a piston stop, real bad idea.

Best of luck on this, and reach out if you have any questions.

Re: Restoring a 1978 Motobecane 50V

Bob Chesarek /

If I get a piston stop Mike, what method did you use to crack the nut? Impact, heat, breaker bar? Thanks again.

Re: Restoring a 1978 Motobecane 50V

Mike McScoutington /

Just a 3/8” ratchet and a good ol’ hingggfffph. I would stay clear of heat in this instance. Maybe a few drops of penetrating oil to see why that gets you and then. You can also try the tighten it a touch to see if you can get things moving. An impact would do alright, but I didn’t have one until recently. A whack on the end of the ratchet with mallet is essentially the same thing while being slightly less aggressive. Jerk they call that, 3rd derivative of position…#PhysicsShit

Re: Restoring a 1978 Motobecane 50V

You're going through all of Rebel Moby's stuff in the wiki, right? There is no substitute for his suggestions combined with some proper tools. Soak with Kano Kroil or a 50/60 mix of ATF and acetone penetrant, proper motorcycle flywheel holder ($25 on flea-bay) and an impact (in reverse!) should bust it loose. Don't hesitate to give it a nudge with a hammer and chisel if needed. Get the aftermarket hex replacement nut in your basket at treats--no more Novi nuts!. Keep at it, man. Mobys are worth the trouble.

Re: Restoring a 1978 Motobecane 50V

> Gen Xer wrote:

> -------------------------------------------------------

> You're going through all of Rebel Moby's stuff in the wiki, right? There

> is no substitute for his suggestions combined with some proper tools.

> Soak with Kano Kroil or a 50/60 mix of ATF and acetone penetrant, proper

> motorcycle flywheel holder ($25 on flea-bay) and an impact (in reverse!)

> should bust it loose. Don't hesitate to give it a nudge with a hammer

> and chisel if needed. Get the aftermarket hex replacement nut in your

> basket at treats--no more Novi nuts!. Keep at it, man. Mobys are worth

> the trouble.

good to know! because everyone keeps calling mine a "piece of shit"! I myself am getting mine running (100% ripping) first, and then i will worry about cosmetics.

Re: Restoring a 1978 Motobecane 50V

> P D wrote:

> -------------------------------------------------------

> Looking fabulous , Bob . ;)

X2

Re: Restoring a 1978 Motobecane 50V

> P D wrote:

> -------------------------------------------------------

> Looking fabulous , Bob . ;)

X3

Re: Restoring a 1978 Motobecane 50V

Bob Chesarek /

Thanks for the tips. I ordered a flywheel holder from Ebay today. Looks like that will work well and provide some leverage too.

And yes, I have referred to the Rebel Moby Wiki many times, very helpful.

Something that has worked well for me over the years when it comes to cleaning parts, removing surface rust on chrome without scratching or corrosion on brass connectors is this super fine BRASS wire wheel. Was about 5" diameter when I bought it many years ago and it's worn to about half it's original size now but I love this thing. It's so soft you can hold your finger against it at full speed and doesn't make a scratch. I made the arbor from a piece of 3/8" all thread. Couldn't tell you where I purchased the wheel now but I'm sure a search on the web will produce results.

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Re: Restoring a 1978 Motobecane 50V

Bob Chesarek /

Thanks for the complements guys.

Today I restored the stuck and oxidized stock headlight switch. The center movable contact bar had a crack at one end but I repaired / reinforced it with epoxy. Polished all the contacts and applied silicone dielectric grease on the contacts as well as the slider and reassembled. Tested with a meter after installation back in the headlight bucket and it slides and functions as new.

Added a shot of the rear wheel. Looking pretty nice!

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Re: Restoring a 1978 Motobecane 50V

looks great!

Re: Restoring a 1978 Motobecane 50V

Bob Chesarek /

Thanks Ryan!

Re: Restoring a 1978 Motobecane 50V

this is mine, now:

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Re: Restoring a 1978 Motobecane 50V

and this was before:

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Re: Restoring a 1978 Motobecane 50V

same.jpeg

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