serious motobecane Q's...

okay, i have two 51V's (parts bikes) and a 50L (which i am restoring)... i took the carb off one of the 51V's (i think this one is a 51V.. looks identical to the other one which has the faceplate that says 51V... anyways, i digress) the intake says "14" on it, which leads me to believe that it is a 14mm carb.. correct?

on the 50L (which i also think is a 20 mph moped) the carb intake looks MUCH smaller than the one off the 51V... the only markings on it that i could see (i havent taken it off yet.. i was getting woozy from all the fumes) suggested it was a 10 mm carb... is this likely or possible?

ok, what i want to do it replace the carb on the 50L with the one off the 51V... if i use the intake that goes along with the 14mm, there shouldnt be any problem, right?!

also, i dont know if this makes a difference.. but the 50L has the dimoby while the 51V's have the variator... (side note: could i put the variator on the 50L? and how do i get the variator off the 51V.. can't get it to budge)

thanks in advance... i VERY new to the motobecane thing (the motobecane seems to be a VERY different animal from what i usually work on) so any other help/hints/advice would be greatly appreciated!

take care!

casey

Re: serious motobecane Q's...

Ron Brown /

Casey,

I can't answer any of your questions directly, but no one else seems to know so here goes.

If you are unsure about the size of a carb, measure the minimum diameter in the venturi. That is, the area between the air cleaner and the intake. Often, the same carb body and slide are used, then the venturi is machined to the required diameter. If you don't have calipers, use a paper clip or a piece of wire, bend it til it just fits, then measure with a ruler.

As for the intake, compare the two of them and make sure the intake port on the cyilinder matches the size of the intake. The intakes may actually be the same.

I think the variator and dimoby are interchangeable but you need a puller to remove either one. You could try some of the moped shops for this.

You may already know, but the flywheel is attached using a left hand threaded bolt. Use a 3/8" impact driver to unscrew it for access to the points.

Good luck,

Ron

Re: serious motobecane Q's...

thanks ron! okay, you just mentioned something that brought up another problem then... =]

my dimoby seemed to be attached using only one nut... that nut was loose, i spun it off with my hand, and the cup came off (the part with the "pads" around the outside of it.... so, i assume this is broken? what part(s) do you think i am missing? when that "cup" came off, the dimoby was sitting right there inside... i looked on mopedjunkyard's engine diagrams, and mine looked to be the same... no obvious parts missing... if this isnt a good enought description, as soon as i get my dig camera back ill get a few pics so you can see exactly what i am talking about...

also, mopedjunkyard sells flywheel pullers... two different ones... one is "Flywheel Puller CEV/Ducati" and one is "Flywheel Puller CEV/Bosch/Iskra".. will either of these work? also, mopedwarehouse sells "Bosch double sided" flywheel puller....

and.. so if the intakes are the same, i can go with the larger carb? is that the only real variable?

thanks again ron!

casey

Re: serious motobecane Q's...

also.. are motobecane's 12V? from what i read on the mopedjunkyard.. they are...

casey

Re: serious motobecane Q's...

Ron Brown /

> my dimoby seemed to be attached using only one nut... that

> nut was loose, i spun it off with my hand, and the cup came

> off (the part with the "pads" around the outside of it....

> so, i assume this is broken? what part(s) do you think i am

> missing? when that "cup" came off, the dimoby was sitting

> right there inside... i looked on mopedjunkyard's engine

> diagrams, and mine looked to be the same... no obvious parts

> missing... if this isnt a good enought description, as soon

> as i get my dig camera back ill get a few pics so you can see

> exactly what i am talking about...

Caasey, this confuses me, as usual. I have never taken mine off as I have no puller. Look at the end of the crankshaft and the inside surface of the clutch housing "cup" hub. This should be a matching taper. I don't see a key of any kind in my manual, but there may be one. The crankshaft drives the clutch housing through this taper which has to be a perfect fit. The reason for the puller is to break this taper fit joint for disassembly. If this engine was ever run with the taper loose, it would screw uo the taper so you need to check it really carefully for a good fit before using it.

> also, mopedjunkyard sells flywheel pullers... two different

> ones... one is "Flywheel Puller CEV/Ducati" and one is

> "Flywheel Puller CEV/Bosch/Iskra".. will either of these

> work? also, mopedwarehouse sells "Bosch double sided"

> flywheel puller....

>

All of the pullers you are describing here are for magnetos. I would be surprised if they fit but mopedjunkyard should know if they do.

> and.. so if the intakes are the same, i can go with the

> larger carb? is that the only real variable?

>

Sure, you may want to examine the exhaust port and pipe to see if any changes were made on that end that you want to take advantage of.

Ron

Re: serious motobecane Q's...

Ron Brown /

> also.. are motobecane's 12V? from what i read on the

> mopedjunkyard.. they are...

>

After January 1 1978, they were 12 volt, I think regardless of model. I would ckeck the lamp bulbs to be sure.

Ron

Re: serious motobecane Q's...

hey ron.. thanks for all the help... i assume my dimoby is messed up in some way... and i cant even get a spark (i dont think)...

man, these peds are sorta confusing... i DID get the larger carb put on... seems to fit perfect.. just having a little trouble getting the choke cable back where its supposed to be... but thats my problem.. haha

thanks again ron... ill probably have many more questions as this progresses...

casey

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