Jetting in Seattle for me 79 Moby

Did it again... bought another moped.

Motobecanes are new to me and I'm having a bitch of a time getting it running after the teardown and rebuild of the top end. It was running very poorly beforehand so I know it runs. Can't get that stupid NOVI nut off to check the points and timing but since I have a strong spark on a properly gapped plug, I'm chillin on that for now. Solid compression. At this point, I think its the jetting due to my spark plug being all wet n' stuff and fuel finding its way down and out of the exhaust when I try to start it.

It weakly backfired once while trying to start it after letting the gas in the engine housing evaporate then nothing...

Just want to know if anyone is running the sameish setup in Seattle's elevation. I need some halp.

Here is what I'm runnin'

- 1979 50V stock AV7

- tossed the Gertner cuz that shit drove me up a wall and bought a Dellorto 14.12 to keep it stock like and it came with a 57 jet. Float bowl works.

- stock pipe (thinking about boring out wider internal side holes??!!?!?! but that could be stupid???)

- front headlight is not working yet but I know its not an issue with this bike. Tail light is.

I have the 50's even # jet pack from treats to down jet in my cart but wanted to reach out beforehand. Thinking Ill need a 55 or 53. I'm feeling anything in the 40's range is too small but I want to make sure I'm diagnosing this properly because sometimes I'm stupid .... or maybe it's timing... and yes, I know about the decomp.

Also, I hope this is is the right forum. It's kinda borderline on a repair I guess.

Thanks ahead of time and hope to make it to a Moped Monday at Magic Touch soooooooooooooooooooon.


Re: Jetting in Seattle for me 79 Moby

Jessica! Nice score! Motobecanes can have some weird gremlins, I have a few tips for ya. I always ditch the novi ignition coil and replace it with the generic red coil that treatland sells. Works great and the holes line up perfect, make sure you grab a new plug cap too. The novi nut is reverse thread and will come off pretty easy with an impact gun. A 56-62 is usually right for seattle with the black cover and filter screen. Dont go hacking up the pipe, you get minimal gains and just end up making it louder. Come on by the shop next Monday if you have time, I'm there all day, but people usually start trickling in around 7 or 8.

Re: Jetting in Seattle for me 79 Moby

second the white novi coil, they are almost always cracked and shot inside.

the other thing i'd check is those white square-ish plug connections down by the engine, they can get corrosion up in there and give you a weak spark.

i would definitely try to get access to an impact wrench to pop off that flywheel. if they aren't stuck too bad i can usually get them with my M18 cordless but the 1/2" air impact always gets them off with a quickness.

Re: Jetting in Seattle for me 79 Moby

Ok so I have a Peugeot 103 (not a motobecane) but there are allot of similarities. You probabaly don't have to worry about the decomp. unless your hearing an occasional wheezy backfire noise when you turn the engine over. the decomp. just lets the pressure escape the cylinder to make it easier to turn over. if its running right, there will be detonation and you will hear that noise. your current jet size doesn't sound wrong... So I would check your ignition coil and timing.

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