New to mopeds - Could use help giving my Motobecane 7 more umph

Hey everyone,

I'm new to mopeds, and the community in general. A friend got a 50 series, and it was such a blast to ride around that another friend got a Honda Express 2 and I got a 1978 Moby 7 (25mph version) so we can cruise around town.

I have some experience working on cars (not much engine work though), but this whole 2 stroke engine deal is new to me so bear with me. I've read up on the forum and wiki as much as I could, and I know the 7 isn't a favorite and seems trickier to mod than most Mobys, but I could use some advice. It seems to run great right now and I don't expect it to be super fast, but I wanna ride it to work over the summer and it struggles up hills. Hence the need for more umph.

From what I've read, the first thing recommended is to swap out the carb for an SHA 15/15. This model has that funky intake though and I guess there's no aftermarket ones, so how can I make that work? Do I need the 30mph version intake (I've looked, but couldn't find any)? Could I bore out mine? Is there a different carb that would work better on the stock intake? Any other recommended mods for more umph? Don't wanna be in over my head either (porting sounds a bit scary).

Lastly, if anyone in the Santa Cruz CA area wants to teach me some things, that would be sweet too!

Re: New to mopeds - Could use help giving my Motobecane 7 more umph

Looks like you read this already: https://www.mopedarmy.com/wiki/Motobecane_7

Sounds like the upgrades mainly consist of swapping parts from the higher horsepower models and not a lot of aftermarket stuff is available. I would say search for forum posts about people working on these bikes to get more ideas, and make a post in the Buy/Sell forum asking for the parts you need as a start

Re: New to mopeds - Could use help giving my Motobecane 7 more umph

Thanks for the reply. Yeah I read the wiki on it. I’ve done forum searches on it too, but most of what I’ve found has been people suggesting to just sell the 7 and get something easier to mod or people who lucked out and have the 30mph version. I haven’t found an intake/carb solution yet, but I’ll keep looking. I just joined Moped Army today so I haven’t tried the buy/sell yet either, but that’s a great idea. Thanks for the suggestions!

Re: New to mopeds - Could use help giving my Motobecane 7 more umph

Doing the basic maintenance like regreasing wheel bearings and all the other tips in Fred's Guide will help eke out every bit of performance currently available to you.

Might be worth reaching out to the French moped gurus:

Rebel Moby (on this forum rarely now but active on Facebook) and Tomahawk Mopeds (on this forum rarely but active on Instagram.) Bonus chance of getting help from Tomahawk if you can speak French :) (edited)

Re: New to mopeds - Could use help giving my Motobecane 7 more umph

I hadn't seen Fred's guide yet, that's helpful. I've been hankering to disassemble it and check on some of those things (gaskets, good cleaning of the carb, exhaust etc.), but obviously a little nervous to start. I was happy enough that it ran when I bought it (my friends wasn't as lucky with his 50 series), but I guess I'll have to bite the bullet eventually.

And I do speak french, but unfortunately I'm not really on Facebook or Instagram. Maybe I'll reach out to them on here and see if they reply. Thanks again!

Re: New to mopeds - Could use help giving my Motobecane 7 more umph

Yeah, the seven is more along the lines of a solex. Made to be slow on purpose.

Luckily it does have av7 cases. If I were you I'd get an av7 cylinder and Piston, 15mm intake, sha 15 carb and a standard av7 pipe. Correct carb jets.

Basically, you'll be spending all the money to make a 45mph 50v to get a 30mph 7.

Re: New to mopeds - Could use help giving my Motobecane 7 more umph

Yeah, those are all the things I was thinking of potentially doing, although I'm not sure what you mean by a "standard av7 pipe". Can you elaborate?

The issue has been trying to find the 15mm intake, but I just posted in buy/sell so we'll see if I get any bites. Also, what cylinder kits would you recommend? Would a 50cc kit (to stay legal) be better than stock, or would I have to go higher displacement?

And yeah, I understand it will never perform like a 50v, but I love this thing. It's lightweight, small and stylish! I would be quite happy with 30-35mph and the ability to go up hills. I wouldn't mind some rear suspension though!

Re: New to mopeds - Could use help giving my Motobecane 7 more umph

If you have the 15mm stock intake you can easily swap to a 15 SHA, and get a 70cc airsal kit, set ignition timing to about 1.3-1.5mm btdc, leave the rest alone actually, that should be plenty good for a solid 40 with out destroying everything.

The 25mph version has a larger rear sprocket and smaller intake, but if you can find the 35 rear and big intake then you should be good.

Re: New to mopeds - Could use help giving my Motobecane 7 more umph

Thanks for the suggestions! Is my intake (13mm) the same OD as the 15mm? I'm just thinking maybe I could get a professional to bore it out or fabricate one based on mine. I'll look into the sprocket as well.

Thanks for the kit and timing suggestion too. Is there a reason you say the 70cc kit? Is it preferrable over the 75cc? Is the 50cc kit practically the same as stock?

To you, and everyone else who has offered advice, sorry for all the questions. I'm new to this so there's a lot for me to think about.

Re: New to mopeds - Could use help giving my Motobecane 7 more umph

Its easier to read.

Re: New to mopeds - Could use help giving my Motobecane 7 more umph

In my opinion the 74cc kits vibrate too much and the 70 is good without too much vibration, the airsal is more user friendly than the parmakit and the 50 av7 kits are basically a fast stock cylinder, so not really worth it

The 15mm intakes are not too hard to find, if you don't have one, but it would be hard to fab, or cost more at least than to just get a stock one. And it's cool, this place is supposed to be helpful.

Re: New to mopeds - Could use help giving my Motobecane 7 more umph

Eric Davenport /

You are either going to have to drill out your stock intake or find one from a fast model 7. The 50v "bendy" intakes have too much bend. The aftermarket short intakes are too short.

Re: New to mopeds - Could use help giving my Motobecane 7 more umph

Is there any reason an AV7 can't be swapped? It's not necessarily the cheapest route but you have a lot more headroom if you want to go even faster, and more parts are available for either more speed or just replacing anything you wear out. More $ up front but you get it back when/if you sell it later. And if you don't sell and just keep riding forever, all the more reason to bite the AV7 bullet.

Re: New to mopeds - Could use help giving my Motobecane 7 more umph

Hugh, it is an AV7. Like the same one as the other av7 bikes. It's just mounted differently.

Re: New to mopeds - Could use help giving my Motobecane 7 more umph

Learning something new here every day. (edited)

Re: New to mopeds - Could use help giving my Motobecane 7 more umph

Hey everybody,

Thanks to everyone that offered advice! Thanks Mike for recommending I contact Rebel Moby. I did, and he's given me some sage advice already including a suggestion for modding the exhaust.

Also, thanks Jesse. You've been very helpful in this thread, as well as many older threads I've found on the Moby 7! I've looked around online and posted in the buy/sell forum and couldn't find any of the 15mm intakes. So I took it to a machine shop, and the guy should be calling me back pretty soon about whether he can bore it out safely or not. So, hopefully a 15.15 SHA is in my near future. Also, thanks for the explanation on the cylinder kits. I was wondering why I always saw the 75cc and 50cc kits at the same price while the 70cc kit at $25 more, but the vibration explains it.

To Hugh, based on the wiki it is mostly an av7. I think the main difference is just the cylinder head since it mounts differently. I was actually offered an av7 from someone in a PM, so you're not the first person to suggest that.

I'm still in the process of disassembling everything to check gaskets, seals, bearings, clean, regrease and all that fun stuff. Those damn motor mounts are just warping the washers on my homemade tool (help me PB Blaster, you're my only hope)! Now I guess I just gotta decide if I want to kit it or not, but if I'm replacing gaskets anyways it's certainly tempting...

Thanks for all the help and advice. It truly is a weird, but awesome little bike! I'm already used to car forums so I try to do as much reading as possible before asking questions, but you dudes have been very patient and helpful so thanks for that. Loving the moped community so far!

Thanks again, and feel free to keep dropping advice/suggestions on this thread if you want!

Re: New to mopeds - Could use help giving my Motobecane 7 more umph

Some great info in this thread about how to get the absolute most out of this bike: https://www.mopedarmy.com/forums/read.php?1,2849521,2850676,flat=1

/s

Re: New to mopeds - Could use help giving my Motobecane 7 more umph

Oh my god, I didn't see the "/s" and you got me sooo good! I'm jealous of the fab skills, but that thing is a death trap! What a legend, RIP.

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