starting problems

I can`t start my motobecane.ignition and carburator works good.i don`t know how to use the decompressor cable.I want someone to help me.thanks

Re: starting problems

An open decompression valve allows the piston to move without causing high compression .. so it's really easy to pedal /crank the engine over. Some engines are very hard to crank and some people do not have the leg strength to pedal-start an engine without this compresion release.

So, first a decompression valve cable would be activated, opening the decompression valve in the head. Compression is now vented.

Pedals then easily turn the crankshaft and the piston quickly moves up and down, building up some _momentum_

Now the decompression valve cable would be suddenly released, the valve closes, engine compression is developed and the engine fires (and hopefully starts)


First check for spark. Remove the spark plug, reattach it's wire boot and clamp the plug's metal base to the engine fins, grounding the plug.. When cranking you should observe a blue spark at the plug's electrodes. If you see spark, ignition is ok. If you see no spark, first try a brand new spark plug.

After spark is tested and affirmed, spray a bit of Starter Fluid into the plug hole, reinstall the plug and attempt to start. If it starts and runs for a second, fuel delivery is the problem.. the carb is not allowing fuel into the engine.

download and study the Motobecane manuals on THIS PAGE

Re: starting problems

thanks for your instructions.i follow this and i saw more engine to the plug electrode.carb is the problem?

Re: starting problems

_i follow this and i saw more engine to the plug electrode_

can you translate that to english?

If you meant you see a good spark, and that Starter Fluid does allow the engine to run for a moment, yes.. the carburetor is not delivering fuel for some reason.

Re: starting problems

i mean that the spark plug is full of gas.i beleive that the fuel jet doesn`t work good

Re: starting problems

ok .. first you have to test and see if the ignition system can produce a spark.

Since that spark plug is fouled, go find a good spark plug.. a NEW one would be best. Test for spark as previously outlined.


There is no point in going further until you are SURE the ignition can provide a spark. (If the ignition has failed, the spark plug's tip could be soaking wet even if the carburetor is ok)

Re: starting problems

Jason Luther /

the motobecane i just bought is _real_ sensitive to plug type and gap (before the crank blew). get a new plug, the correct plug.

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