Cady goin' slow II

For those of you in touch with my previous post:

https://www.mopedarmy.com/forums/discuss/6/20430/20430/

I completely swapped engine, carb, intake, EVERYTHING related to the engine over from my 30mph M1 to my 20mph Cady. It still goes like 20!

Wondering if it was a clogged exhaust, I loosened it from the cylinder a juust a little to let some more air out. Didn't do much but make it slightly louder.

My only idea is the rear sprocket is 1in bigger than on the Cady. The sprocket holes on the cady are different than the M1, so I can't swap them. Would that _really_ make that much of a difference?

What else could be causing this??

Re: Cady goin' slow II

Have you settled on whether or not that Cady has a variator? If i recall, the motobecanes with variators allow the engine itself to move slightly backwards on it's mounts when the variator shifts to higher "gear". Strong springs return the engine to it's original position when engine RPM decreases. (This action keeps the drive belt taut.)

If you swapped a bunch of stuff but the engine mount system has problems and the engine cannot move, you're still gonna be stuck in "low gear".

Re: Cady goin' slow II

As far as I know-Some of the likely culprits can be as simple as a poorly adjusted throttle cable. Other than that I have a 72 Cady and it isn't very quick, a bigger sproket could do the trick?

Re: Cady goin' slow II

I don't believe it has a variator. It's got these screws to push the engine so the belt's tight. No mechanism to move it back and forth.

Re: Cady goin' slow II

I guess I'll check the throttle cable. When it's out of the carb, it pulls the slide tight up against the top - so I figured it was alright.

I wish I could find a bigger sprocket - the holes on it are very different than any one I've seen.

How fast does your Cady go? Could you measure the rear sprocket for me?

Thanks!

Re: Cady goin' slow II

You seem a bit unsure about what one is and where a variator might be.

See attachment . It is from a motobecane manual.

A variator is a belt-drive / variable-pulley unit attached to the crankshaft's end. It's belt might then drive a pully-sprocket combination and chain .. the chain would then go back and drive the rear wheel sprocket.

But there are other ways to setup a variator. For instance, some Hondas don't use a chain.. the variator belt instead directly drives a gearbox on the rear wheel... no chain or sprockets needed.

1117323257_mbvar.jpg

Re: Cady goin' slow II

I don't have the speedo on mine it's a "custom", in all honesty it was missing tonnes of parts when I got it. So I did a lot of trial and error stuff with it. I had one of those shitty bicycle speedo's on it and it would shut off at about 30kmh and I would still be gaining speed. my guess would be 40kmh tops. I am on my way out the door but I promise I will measure my sprocket Sunday afternoon and reply to the post again in the evening-- One idea i had is to find a similar sprocket (only a bit larger) from a bike store (used and cheap) and modify it? When I check out my sprocket tommorow i'll think of some ideas!

Re: Cady goin' slow II

Okay yeah, I'm not too sure I guess. I'm familiar to the Hobbit's or the Bravo's, but was unaware that motobecanes have them.

What can I look for on this bike that would tell me?

Re: Cady goin' slow II

man.. i got really no idea about mobos.. but it should be obvious if theres a variator.

you will at least see a drive V-belt coming off the engine. If so a pulley of some sort (perhaps a variator) is on the engine. This belt will then transfer power to a sprocket and to the rear wheel through the chain..

Of course some pulley-driven bikes have a simple, solid pulley, and dont have a variable pulley (variator).

Re: Cady goin' slow II

I highly doubt there is a variator on this thing. It's like the smallest moped engine I've ever seen.

There is no mechanism for moving the engine, nor any roller weights in the clutch to tighten belt slack.

Basically the engine turns the belt, which turns the huge disk that the pedals go into, which turns the rear wheel. There's not a bigger sprocket on the other side of the big disk either.

:: hrumph ::

I've tried tightening and loosening the belt. Other than maybe 1mph it didn't do anything. Would a rear sprocket slow it down 10mph?

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