Motobecane 50 V help?!

I just got my hands on a '79 mobylette 50V. This is my first moped and I'm defintiely a novice with any type of engines.

I got the 25 mph model and on a good stretch of flat it barely hits 20 (according to the Moby speedometer). After riding it for a few hours the first night, it was running considerably slower on the second day, topping out around 10-15 mph.

The carb could use a good cleaning I'm sure, but I'd rather just buy a new Dellorto at this point. I'd like to get it running 35-40mph consistently with good acceleration. It's currently running off the stock Gurtner and the AV 7 engine. What's the best upgrades to get it running solid and a little faster at this point?

The first step I'm thinking of is pick up a 15.15mm Dellorto SHA Carb, replace some cables and throttle assembly, and slap on a new fuel petcock. Any suggestions/advice?

Once I get through those upgrades, I'd like to put on a performance exhaust and then, further down the road upgrade to the AV 10 engine and put in a speed kit. With thsi in mind, is it wiser to go with a bigger carb or will that not work properly with the current engine?

I'm already in love with this little fox and I really want to learn everything there is learn about her so I can get her nice and speedy.

Motobecane 50 V help?!


1. SEARCH. Seriously. Not being mean or anything. If you want to learn about moby's this is the perfect place, and hundreds of people have been in your shoes already, so look in the forums and Wiki for info. All your questions can be answered easily by searching for a couple hours. Keep in mind that the wiki has a huge wealth of info on mobys, so use it!

2. Ditch the gurtner carb and get an SHA. Do not be totally sold on the 15.15; it will kill your low end a bit but give you reliabilty, simplicity and some mid/top end. Look around and consider a 14.12 carb as well.

3. 35-40 is easyily done on stock parts: Currently I am running about 40 or a bit better RELIABLY on a ported stock 30mph cylinder and a dellorto carb, stock exaust and matched case. Similar results are easy with a 25mph cylinder too. Get yer dremel out!

4. Hardwire hardwire hardwire. No excuses. It will make your life easier and more fun. Look in the wiki. Also look at Mabecane's website for a guide on putting in a new condensor.

5. If you are inexperienced with mopeds and engines in general, I urge you to take a step back from thinking about AV10's quite yet. Not to discourage you, but dropping bux on expensive AV10 goodies is a bad way to introduce yourself to mopeds. Why skip all the fun of learning stock AV7's? They can be great, and are a perfect engine to learn on. Master the basics before moving on to master blaster status

6. New cables: Yes New throttle assembly: only if it is broken; most likely it will be fine. Drop the variator down to 2 balls; clean everything and lubricate. It takes a lot of work to revive an old moby, but the results are worth the work. If you have specific quetions don't hesitate to email me

Motobecane 50 V help?!

Oh yeah, and don't worry about performance until your bike is a solid running reliable stock bike.

Re: Motobecane 50 V help?!

Is the belt beat up and old??

Re: Motobecane 50 V help?!

In terms of porting, are you talking about just matching up the exhaust, intake, and transfer ports?

Re: Motobecane 50 V help?!

READ. Period. Just read about it and you will figure it all out. And by "porting" I mean enlarging the intake an exhaust. Case matching refers to matching the case transfers to the transfers in the cylinder.

Use the wiki

Re: Motobecane 50 V help?!

julians post should be the home page for sage words people, sage words.

Re: Motobecane 50 V help?!

To me it sounds like your gurtner carb. the choke is very critical realy critical. after the motobecane is running like yours is you have about 1/8th in to play with. start the moped and start driving down the road and start fouling around with the lever on the left hand side thats the choke. you can loosen it or tighten it but very little to much it will cut off and to less it well cut off. this happens on all my gurtner carbs but there very reliable when you get them running. if you get rid of it contact me.

but this usually the choke if it not its a whole nother thing but i bet it the carb

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account