Need motobecane timing advice

I have a Motobecane Cady of unknown year. It looks a lot like the 3 pics below, which range from 1972 to 1980.

http://mopedarmy.com/photos/brand/1/1729/

http://mopedarmy.com/photos/brand/1/2466/

http://mopedarmy.com/photos/brand/1/2162/

It has no power and can't keep a 90 pound person at speed. I've cleaned the carb, changed the plug. Now I'm down to the breaker point and timing adjustment and this is the problem:

According to the service manual, you attach an ohmmeter to the grey wire that goes from the stator to the coil, and one to the ground, and you set the timing that way. Unfortunately, I'm getting a closed circuit measuring this way. Ie. the ohmeter always indicates closed circuit, no matter what the breaker point position (contacting or not). So I can't set the timing this way. Even when I put the probes on the 2 breaker points themselves(see pic), it shows a closed circuit.

The manual says that mopeds made after 1978 use a 12 volt system, and it also says that you can't use an ohmmeter for these -- you have to use a timing light tester that motobecane supplies. Maybe this moped is post 1978, and maybe I need an alternate method of adjusting timing. I don't have a timing light.

Does anyone out there know if what I've indicated above is a serious electrical problem, or do I need an alternate method of testing when breaker contact is being made? Any help would be appreciated.

Thor

1104265218_img_1780a.jpg

Re: Need motobecane timing advice

I'm pretty sure there is always some resistance in the circuit even when the points are open. So, a simple yes/no continuity check will always show continuity.

In the same way, a timing light will always be lit, but when the points begin to open the light will suddenly get dim (or is it brighter? i forget ;)

You can make a timing light.. a flashlight battery or two and it's low voltage bulb. I think you hook it up just like you would the ohmmeter. Slowly turn the flywheel and note where the bulb's brightless changes.

Before you decide it's a ignition problem, check the exhaust ports and pipes for carbon buildup... Fred's Guide (in the resources section) has lots of other tuneup checks that should be performed.

Re: Need motobecane timing advice

you can check with just a continutity tester. there are 3 wires coming off the stator plate Pull both of the removable wires off the stator plate (white and brown on a 50v). follow the 3rd (grey wire) up to the spark plug, unhitch it from everything (it continues up to the kill switch as well) put one end of the meter to the gray wire from the stator, put the other wire to ground. now you should turn the flywheel and get a good reading.

I bought a little plastic ruler with milimeters on it, I broke it to make it shorter and wraped electrical tape around one end to make it fatter. Then I could wedge the ruller in between cooling fins on the engine near the spark plug hole pointing up.

now stick an allen wrench in the hole, and watch it go up and down against the ruler. It helps if the multimeter has a beeping sound, then you do not need to look at it.

Cadys should be 1.5mm before TDC .35mm gap

Re: Need motobecane timing advice

I have that manual too, I was confused, and was getting the same results as you are untill I figured out that way to make it work. I have set timing just fine using my mulimeter on post 1978 mobies.

Re: Need motobecane timing advice

Jason Luther /

yeah, the points arent like on or off. like joes light bulb you can use a multimeter in the same fashion. the needle will just barely jump when the points break. do you have the meter in the correct range? select the range that gives a reading other than infinity or zero.-jason

Re: Need motobecane timing advice

Thank you all for the tips. I did indeed reset my ohmmeter to its most sensitive scale (0-200 ohms). And it does produce a slight, but consistent and noticeable change when the points contact. I'll try to adjust the timing this way tomorrow. I put a plastic straw into the spark plug cavity and it moves nicely against a graduated ruler, so setting the 1.5 mm should be achievable.

Thanks again.

Thor

Re: Need motobecane timing advice

Actually if you follow the instructions I wrote, you will not have to look for slight ohm changes, it should go from no resistance, to dead short.

Re: Need motobecane timing advice

Dan,

The engine manual that I downloaded (not sure exactly which engine I have though (any way to tell?), says that the gap should be .35 to.40 mm and the advance should be 2mm. Is 1.5 mm better?

Thor

Re: Need motobecane timing advice

Allen Murphy /

Dan, I went throught same problem until I realized that I had to disconnect the ground and the feed wire to the coil BOTH before I could use a VOM or test light.

If I left the ground connected, it would just back-feed through the lighting magneto, and give me no indication of when the points had opened.

Live and learn, Al Murphy

Re: Need motobecane timing advice

I have the manual that you spoke of, and I have the haynes manual that covers all models. It says 2mm for some models, and 1.5 for others. The Cady is listed as 1.5mm

The haynes manual covers mopeds built from 1965 to 1976, so maybe it is not completely accurate information.

Re: Need motobecane timing advice

I'll aim for 1.5 to 2 mm advance. I suspect that you can't set it that precisely anyway. Thanks again to everyone who contributed.

Thor

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