Motobecane Mobylette 1978 Rev up and bog down

Hello!

Long time lurker, first time poster (please lemme know if I'm missing any information) and first year rider/mechanic.

So, I rev my Moby up for a spin and it feels fine for a while, 27-30 on flat.

But after a bit (10/15 mins) , it feels very boggy, especially going from a stop. Pedaling even at 10mphish is a struggle.

The exhaust has be cleaned twice and I've seafoamed my pistons twice. I've cleaned from one end of the bike to the other as best I could.

I'm running 4oz oil/Gallon in my mix with a splash of engine cleaner additives.

It revs up and then down in a few second intervals and I'm unsure what causes it.

I'm waiting on the local shop to open in a week here in Vancouver (BC) for a new belt thinking that that may be an issue, such as it fails to grip. Currently using a Dayco 5L320.

Everything is stock except for a fresh Dellorta SHA 15.15 carb with a 68 jet

I'm waiting on some tools from Treats to swap out the clutch for a new stock one and to do my points/timing.

Any advice is greatly appreciated

J

Re: Motobecane Mobylette 1978 Rev up and bog down

Downhill Harvey (OFMC) /

https://www.mopedarmy.com/wiki/Vacuum_leak

https://www.mopedarmy.com/wiki/Plug_chop

Jet could be too big.

Search rebelmoby, he's the guru.

Re: Motobecane Mobylette 1978 Rev up and bog down

heat messes with electronics, if your coil is chalky its bad or look up condenser. Id first add an extra ground wire from frame to motor might help.

Re: Motobecane Mobylette 1978 Rev up and bog down

Downhill Harvey (OFMC) /

4oz/gal is too much, use 2.5oz

Re: Motobecane Mobylette 1978 Rev up and bog down

jacob, this is a diy forum, learn how to work on your own bike, do not take it in to a shop unless you have zero coordination.

Re: Motobecane Mobylette 1978 Rev up and bog down

I'm trying bud, but this has got me stumped.

Re: Motobecane Mobylette 1978 Rev up and bog down

Staring at the bike will not fix it, the belt is not the problem. you know how to take a spark plug off right? To help tell if its running rich like dh^ take it off and post a pict. color etc tells whats happening insidewhere the action is, everone likes picts.

Re: Motobecane Mobylette 1978 Rev up and bog down

> Downhill Harvey (OFMC) Wrote:

> -------------------------------------------------------

> 4oz/gal is too much, use 2.5oz

4oz is stock mix, will not cause running issues.

Re: Motobecane Mobylette 1978 Rev up and bog down

Looks like it's points/electrical - I havent done a full air check, but I've tighten up my carb a bit more. Also found my tire rubbed my brake light cable out - so I've gotta fix that and my horn connections.

Re: Motobecane Mobylette 1978 Rev up and bog down

I had a similar experience and found that the breather hole in the gas cap was blocked. it was creating negative pressure preventing good flow of fuel.

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