Motobecane V50 Sputters??

I just bought this really nice looking 1980 V50 30MPH model and got it running, kinda, it sputters constantly,I changed the plug, no change, I cleaned the points, no change, I changed the coil wire and end, no change. The carb was pretty clean inside and does not leak any gas so I think it is OK and it doen't run any better with the choke on. I believe it is an ignition problem. The engine will idle or run wide open, sputtering the whole time. Since there are no holes in the flywheel, I can't see if the points are sparking excessively. This is my first Motobecane (not counting my parts bike). Any ideas would be appreciated.

Re: Motobecane V50 Sputters??

Michael Dane /

I forgot to add that all of the lights and horn are working normally and the magneto is very clean looking inside, looks like new. Bike has always been stored indoors.

Re: Motobecane V50 Sputters??

Check the timing, and points gap

https://www.mopedarmy.com/forums/discuss/1/173041/173041/

Also check the exhaust for blockage.

Does run with you on it? How fast?

Re: Motobecane V50 Sputters??

i would suggest to put fresh gas in

Re: Motobecane V50 Sputters??

Sounds like the condenser is bad. This will cause the points to arc and the spark plug to fire inconsistently (sputter). The bike will feel like it wants to really go but has slow acceleration. DO NOT BUY THE REPLACEMENT FROM HANDY BIKES, Ive tried one from them in your same year bike and had the same problem. If you can pull it from your parts bike do so, if not try to find a novi one. hope this helps.

-backwards

Re: Motobecane V50 Sputters??

Michael Dane /

I did clean the tank and refill with fresh gas after cleaning the carb.

Re: Motobecane V50 Sputters??

Michael Dane /

It runs with me on it but there are also issues with the driven pulley at the moment. I can feel the power at times though. It probably goes 10mph. Points gap looks good. I have to assume the timing would be Ok or good enough for it to at least run smoothly. I'm going to pull the muffler off as there is a slight leak at the cylinder. Thanks for the tips

Re: Motobecane V50 Sputters??

Michael Dane /

I was thinking condenser too and also going to give Handybikes a try for replacement. The guy I got my parts bike from said it lost spark so I'm not sure it is a good candidate for a condenser. Probably worth a try. Does the points cam have to come off to replace the condenser? Thanks for the tips especially the one about the aftermarket condenser.

Re: Motobecane V50 Sputters??

_Does the points cam have to come off to replace the condenser?_

Not from what I recall. Condenser is held by two screws, and a wire lead to the points. The cam does not interfere with it.

Re: Motobecane V50 Sputters??

It depends on the year of the moped.

I think you will have to take it off on a 77,

78 and later they condenser is on the outside of the magnetto.

Try to take it off, see what happens

Re: Motobecane V50 Sputters??

Mike Scouty McScoutington /

i have pulled the internal condenser by just puling the coils and not touching the cam. its kinda a pain, but not to bad.

Re: Motobecane V50 Sputters??

Here I've been thinking all along that the condensor was the thing mounted under the gas tank that the plug wire comes out of. What's that thing?

Re: Motobecane V50 Sputters??

John Joedicke /

Coil

Re: Motobecane V50 Sputters??

Michael Dane /

I got the V50 running great! Thanks for all the help. The problem was the condenser. I took the one from my parts bike and installed it, it fired right up and runs perfectly. FWIW both condensers had the same resistance according to my two OHM meters. They both showed open or infinate. I don't think that you check them that way. I have several different NOS VW condensers and they also showed open on the meters. I really don't think 6V condensers are any different from 12V condensers. I have done many 6 to 12 volt conversions on old VW's and never had any problems with them. The coil does matter for sure though. Thanks again: DT

Re: Motobecane V50 Sputters??

All condensers will read as open on an ohmmeter, whether or not they are good. An ohmmeter uses a small DC current to measure resistance, and it's the job of a condenser (capacitor) to block the flow of DC - hence, open or infinite resistance.

If a condenser reads as anything other than open, it is bad. But, if it does read open, this does not mean that it is good.

The only real way to test one is with a capacitor checker - and the old-fashioned style (that allows you to apply a high voltage) is the best type. I have an old Heathkit LCR tester for this use.

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