motobecane 51V upgrades

hi all, got some motobecane newbie questions...

i looked a bit in the wiki and did some searches, but was looking for the latest answers and such...

so i've got a reed valve av10 on a 51V from france (see buy/sell for my recent acquisition).

it's all stock and runs well this way, but i was wondering what simple upgrades are possible with this setup. i'm looking mostly for dellorto carb upgrades, reed cages, variators, pipes that allow me to keep stand/pedals.

i've got some experience with vespa engine rebuilds, kitting of puch/vespa, variator stuff but never with a motobecane.

any tips/advice on this is definitely appreciated.

Re: motobecane 51V upgrades

If you are talking about the blue 51v you just bought on the forum then don't upgrade it. Buy another motobecane and upgrade that to an av10. The stock setup and story that go with it are too much to ruin.

Re: motobecane 51V upgrades

Yea right!

It came over from france with a motobecane honcho so he could ride it around America only to end up with someone who wont be satisfied with it the way it is.

Sad Sad times.

Makes me want to cry a little.

Re: motobecane 51V upgrades

yes, it is beautiful and has a touching story to it, but i have never been against simple non-invasive changes. like maybe a dellorto carb with matching intake which i have a lot of happy experiences with. but i would certainly not get any large pipe that would require loss of pedals or center stand. i'm against any cutting, grinding, or hacking of any kind to this bike.

if i were to do anything (which i'm not sure i will) i would make any change reversible to original.

anyway, you bring up an interesting philosophical point. i got this moped primarily not because it was a collectors item, but because i know it is a solid moped with the best of features. but i am respectful of this (and all) mopeds so i never repaint, and avoid permanent irreversible changes. if you think this is overly sad, tell me why, maybe i'll understand better.

i'm more interested in careful quality and a bit less about sentiment.

Re: motobecane 51V upgrades

also, i'll share that i also intent to replace the rear taillight lens that has a slight crack with a NOS one when i find it and am looking for a replacement neck lock. i intend to keep this in top shape.

Re: motobecane 51V upgrades

I agree with those above, but can also understand why you wanna go a little faster. I'd say 15mm SHA, port the stock cylinder, keep the pipe, and maybe get a varplus. I am still very skeptical of any changes.

Re: motobecane 51V upgrades

thanks for your input motobee. i was considering something along those lines. the 15mm sha with matching malossi reed valve intake. i'm guessing the malossi variator would give greater gear range (with perhaps higher top speed), but i'm not sure.

i agree it does run well as is, but i sense that the gurtner isn't quite giving enough mixture to the cylinder.

i don't think i want to port the cylinder because that would be cutting or grinding and that would be a permanent modification that i'm not comfortable with.

Re: motobecane 51V upgrades

That Malossi variator would require a lot more work then just putting it on, unless you are talking about the varplus, the modified movable cheek for the stock variator, it does help with tuning but it's also a pain in the ass in terms with reliability. I've had the roller weights get stuck all the way out before and had to get a screwdriver to punch them back down.

Porting out the stock cylinder will net you a decent performance boost. There was a very informative post on about porting out the stock av10 cylinder, it gave detailed transfer timings, carb/pipe matching for different degrees of porting AND fuel consumption, but alas, my bookmark of the thread no longer works. Take a look around that site, it's got a lot of very knowledgeable tunes on it.

Re: motobecane 51V upgrades

ventilxp crashed and is now a shadow of its former self. they lost all their content.

you want to do this:

dellorto 15:15 carb with a jet in the mid to upper 70s.

doppler ER3 reed setup. these are carbon fiber and let in waay more air than the stock setup.

check and see if that bike has a 3 or 4 ball variator. i'm betting its a 4. if it is, take it apart and take two of those balls out.

widen the exhaust port about 1mm on each side, raise it about 1-2mm. this wont hurt anything, and stock AV10 cylinders are a dime a dozen.

get a 50cc malossi hi-comp head with the decompression valve.

i bet that bike has points too. make sure all that stuff is in good shape, and you may want to retard the timing just a 'lil bit. none of this will change the appearance of the bike whatsoever and you'll be very pleased with the results.

Re: motobecane 51V upgrades

thanks shaler.

i ordered the 15.15 carb (with cable choke), and got the 50cc malossi hi-comp head with decompression hole, as well as the malossi reed intake for the av10 from malossidirect. where would one get the doppler intake? i see easyparts in holland has them, but nothing in the states?

Re: motobecane 51V upgrades

nothing but doppler variators, crankshafts and pipes are being sold stateside right now that i know of. if you got the malossi you should be golden.

Re: motobecane 51V upgrades

hi it's been a couple of months and i've made some changes. the attached pic shows what it looks like now.

here's what i've done in terms of tuning

1 parmakit 15mm intake but with stock reeds & cage

2 15.15 dellorto

3 malossi hi comp head

i kept the stock reed cage because it looked a bit better made and fit for the engine, but i may try out the parmakit one.

so far, it is a lot peppier and the carburetion is very reliable (definite improvement over the gurtner). but acceleration from start isn't great so my next step will be to take a look at the variator. any tips on opening it up? so 2/4 balls in there is enough? i hear a bit of rattling coming from the variator...if this is abnormal, let me know.

so just for clarification, the ninja g3 requires loss of center stand, but i've heard that the stand mount also has to be cut off...anyone verify this? i wouldn't want to cut this.


Re: motobecane 51V upgrades

What a beautiful and rare find stateside. Love that shit and lock it up all the time. Get one of those big kryptonite chains or a werewolf

So yes, G3 requires loss of kickstand, and while it is not totally necessary to lose part of the frame, it makes it fit much nicer and keeps it from rubbing.

That variator will work fine with 2 balls in, and will give you a big improvement in acceleration. Do it! If the rattling is just as you come to a stop, that is normal as the balls fall down when the rpms get very low, not enough force to keep them pushed out against the cheek. Lots of noise at higher speeds is questionable.

Re: motobecane 51V upgrades

thanks carpy. yeah, the rattling comes when i come to a stop, so hopefully it's not big issue. i'll take a closer look when i open the variator.

i think i'm gonna avoid the ninja g3...i'd love fast performance (together with the doppler 50) but i'd just feel too bad to cut the frame.

i have this ABUS serious motorcycle chain lock so i think it's the best i can do for now...

also have a 60 jet in the dellorto (downjetted from 68 after i noticed i was fouling b9hs plugs (all i had around for my kitted magnum) but yesterday put in a b7hs with 60 and it seems fine. just bad acceleration).

Re: motobecane 51V upgrades

Malossi varplus...

The best upgrade for the money in the moped world.

Re: motobecane 51V upgrades

Are those the side plates that came with it?

Maybe you should get a kit for this moped. That way you could put the original jug off to the side for posterity.

If you want to come down to Bmore and ride we would love to see this Moby.

Re: motobecane 51V upgrades

Yeah the varplus is absolutely awesome for the money. Very good.

Re: motobecane 51V upgrades

those side plates are not original to the moped...they are the correct fit but have the "le moped" paint job, since the le moped is just the usa version of the 51v. it came with incorrect side panels so this was the best i could find...maybe one day i'll get the ones with the right paint job too...

also the seat and rack are from a le moped

yeah so i've been reading about the malossi multivar...i have a malossi multivar for my piaggio's great.

but that's strange that they wear out for the motobecane ones.

Re: motobecane 51V upgrades

mickr...i'm planning a trip down to dc this summer...perhaps i'll make a stop in bmore? looks like you've got a good collection yourself

Re: motobecane 51V upgrades

naaa dude, you should put some clubmans on it, powder-coat the frame, chop the rear fender, get a puch 1.5, hellyea siiiiiiick.

Re: motobecane 51V upgrades

my newest addition AV51 mbk not finished found in parts



Re: motobecane 51V upgrades

cool, now that is a rare one...

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