Motobecane Cady - kinda slow

So I just got a Cady in the mail on friday. I put it all back together, cleaned out the carb and all that biznazz, and it runs great.


For some reason it's going pretty slow. The belt on it looks brand new, the drive chain is nice and tight. The carb is clean as a whistle. What could be causing this?

This is my first time to work on the smaller Motobecane engines. It's also kind of loud, but I can't find where you can change the crankcase oil on it.

Any help will be appreciated!



Re: Motobecane Cady - kinda slow

Not sure why it's slow, other than typical things like compression, etc. How slow is slow?

And AFAIK, there is no crankcase oil to change. Only 4-cycles have crankcase oil.. some 2-cycles have oil for the transmission, etc, but not for the crankcase. Crankcase lubrication is provided by the gas/oil premix.

Re: Motobecane Cady - kinda slow

It's going about 20mph or so. Could this be points or anything?

It seems the bike is just like it was when it was originally purchased. Original spark plug, original belt, original tires, etc. It looks like it's never been ridden either, everything is brand new.

Re: Motobecane Cady - kinda slow

Yeah I'm not much of an expert but maybe the carb should be adjusted. Does it sound like the motor is running a a low RPM? Because by adjusting the throttle and carb, you could make the top speed greater but with Higher RPMs.

Re: Motobecane Cady - kinda slow

Motobecane made some models designed to only top out around 20. Perhaps the cady is one...

Does the moped act like it wants to go faster, through noises or anything?

If I had my Cady running, I would compare speeds with you.

I'm pretty sure that your Cady is the only running one I have ever heard of, so that's something to be proud of!

Re: Motobecane Cady - kinda slow

Haha it's a beaut. I got it for my girlfriend (her second Motobecane) but I'm trying to get it running nice before she scoots off on it.

I just read somewhere that the mixture is actually 25:1 and not 50:1!! That would explain the loudness and ... possibly the speed? What do you think?

I'll put the new mix in there tomorrow morning.

Re: Motobecane Cady - kinda slow

IIRC, motobecane calls for 25:1 for break-in, and 32:1 for general use. With a modern synthetic oil, you should be fine running 40:1, or even a little higher.

If you are too lean on the oil, the initial effect is that the bike makes more power (less drag from scraping oil off of the cylinder walls, squeezing it out of bearings, etc) up until the point where it runs dry and begins to seize.

And yes, motobecane made 20mph models (which are actually rated for 24mph). If it's really pristine, take a look at the sticker on the top of the airbox. It should have the speed rating on it - 20, 25 or 30.

But the loudness is concerning me. Is it exhaust noise, or mechanical noise from the engine? The motobecane exhaust is very effective (quiet) and the motors are also mechanically quiet. If yours is clattering from the top end, it's time to check compression

Re: Motobecane Cady - kinda slow

Mike Scouty McScoutington /

if it is exhaust noise check to make sure that the exhaust gasket is good and in place. that will make a world of difference.

Re: Motobecane Cady - kinda slow

Okay, I checked the back of the airbox and it had 2 letters then 20, so I figure that means 20mph.


I took the carb off my M1, which is a 30 model and put it on the Cady. Still goes 20!! What other differences were there between the 20 and 30mph models?

Re: Motobecane Cady - kinda slow

Also, the loudness I spoke of doesn't seem to be a problem. It just rattles around a little - it could just be a loose bolt.

Re: Motobecane Cady - kinda slow

You may want to check your drive chains...The manual states that if too tight...speed will suffer.

It states to set the tension with rider on board and about a cm or so slack...

Hope this helps.....


Re: Motobecane Cady - kinda slow

on Puchs the 12mm manifold is restrictive.. maybe if you bore out the manifold to 14mm i would help! Just a thought :P

Re: Motobecane Cady - kinda slow

I'll check that out today.

What about the rear sprocket? Maybe that's smaller than the 30mph models.

That's the only other thing I can think of that would be different between the 2 models - I doubt they put different pistons on these.

Re: Motobecane Cady - kinda slow

Good point. They did put a really restricted intake on the 20mph version. Look at it and check on the size, if it looks really realy thin..and compare it to the 30mph verison you have...

Re: Motobecane Cady - kinda slow

If that's the ORIGINAL spark plug,replace it. Somtimes a problem can be as simple as an old sparkplug. Make sure no brakes are dragging. That doesn't have a variator does it? If it had a variator,the variator might be stuck,limiting top speed. don-ohio

Re: Motobecane Cady - kinda slow

No it's a new spark plug - though to tell you the truth it's possible the one I had matched wasn't the right one anyways.

No variator as far as I know.

Could it be the rear sprocket? It's an inch smaller than my M1's

Re: Motobecane Cady - kinda slow


I was comparing my 50V and 40T parts the other day, and I noticed that the 40T has a much smaller rear sprocket than the 50V. This would tend to give a higher top speed, but the 40 also lacks the gearing that the variator gives on the 50 - so I'm not sure how the ratio works out.

Re: Motobecane Cady - kinda slow

Yeah it's about an inch smaller than my M1's

Does the Cady have a variator?

Re: Motobecane Cady - kinda slow

This is probably a better question for Larry, but I'll go out on a limb and say that I'm pretty darn sure it does not.

It's easy enough to find out.. if the motor moves fore & aft in the frame as the engine is revved, then it has a variator. The variator action will pull the motor rearward as RPMs increase.

Re: Motobecane Cady - kinda slow

Yeah, no variator on this one.

Other than the rear sprocket, there's not much difference unless it's something within the engine itself.

I'm 2 steps away from just swapping engines and seeing what it does.

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account