Can a Moby 50V engine fit a 40V?

Kiel the Canuck /

Hi everyone!

Long time lurker, finally got myself a moped. It's a 1970 Motobecane 40V basketcase... with a badly seized engine. The previous owner attempted to un-seize it, but it's basically dead (water got into the case, got rust all over the crank too.

I found a 50V engine on the 'bay ( ), but would it work on mine?

You can see a pic of mine from the seller's ad on CL here:

Re: Can a Moby 50V engine fit a 40V?

CL link does not work

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(The title on the listings page will be removed in just a few minutes.)

Yes the 50V motor will fir on your 40V

Re: Can a Moby 50V engine fit a 40V?

Kiel the Canuck /

Thanks for the quick answer! I'll admit I'm quite the newbie to these bikes, and my engine is currently a box of parts...

If it's not too much bother, what would you say the engine in that auction would need in order to run? I'm trying to work out if I can buy that engine and combine it with the parts I have on hand.



Re: Can a Moby 50V engine fit a 40V?

Sorry I did not look before at the link to eBay you posted...


It is overpriced for a misrepresented motor. The coils have been cut from the ignition, it is not from a 50V because the V means Variator and it has the Dimoby single speed clutch. It is a 20mph motor with the undersize intake and will have feeble size transfers.

Post on the Buy/Sell section of MA and look there often, someone will have a goodly motor for you that is not a ripoff.

On a motor with no history you can expect to change all the gaskets (head, base, carter half, intake, exhause) as well as the spi seals on the crank. Refreshing the main bearings would be a good idea as well. Run you about $12 for the gaskets set and $30 for bearing and spi seal.

Also get the crank/clutch puller tool which is under $20 if you dont have one or there is not someone that you can beg one from near you. (edited)

Re: Can a Moby 50V engine fit a 40V?

Kiel the Canuck /

Wow, thanks for helping me dodge that bullet!

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