I have a Motobecane moped that wont start even after all the troubleshooting procedures, except that when i plug up the spark plug hole with my finger and turn the wheel, air is escaping from what seems to be a tiny hole in the side of the "piston-cylinder housing" ( I dont know the actual term for that piece so that's what i call it). Is there supposed to be a tiny hole there or not? and if not, can i fix it by welding it shut or to i need to replace it?
If that is the decompression port, there should be a decompression valve/switch/lever thingy. Look at some of the posts in the past and also go to somewhere like themopedjunkyard.com and look at the schematics of your motor. It should give you an indication of what you are missing.
I don't own a motobecane but figuring out your problem should be easy for you once you figure out what goes into that hole. DON'T just weld it closed before checking though. are you getting any firing even with the hole?
The have a price for the decompression release cable but I am not sure what parts you have and what is missing (they had a picture of a bag so no help with a picture). I might would give mopedwarehouse a call and see if they have the parts you need. If not, call the moped junk yard to see what parts you are in need of.
I don't know if you can get enough compression to get it to start without having the decompression switch in place. Even if you could, it wouldn't run very good. If you closed the hole, you might have a little trouble getting it to crank. (Too much compression to overcome with the pedal start?)
Jamie is about right if it is the decomp valve. This is on the head, next to the spark plug and is operated by a cable from a lever on the right handlebar. Make sure the cable is allowing it to close.
If it is, take the head off, it is easy to do, and look from the inside. I have no idea what retains the decomp valve but it only comes out of the head from the inside so if it is missing, go fishing in the crankcase with a magnet.
Post again with more details.
match and a gas can will fix it
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