Motobecane tune ups?

Andrew Spoering /

I rececently got a '77 Motobecane 50v that's in beautiful condition. It wasn't running when I got it, but a new plug, a little cleaning, and a carb rebuild later and the thing is running awesome. However, I'd kinda like it to run a little faster (it's the 30mph model, and accually tops out at around 32-33). I know that with a 2-stroke engine you really shouldn't deconstrict the air intake or the exhaust for fear of messing up the balance of the exhaust/intake, and I'm pretty sure that even if I did that the gearing (that huge pie-plate of a gear) wouldn't allow greater speed anyway. So is there any way that anyone can think of that'll get me another couple mph out of it? Thanks!

Re: Motobecane tune ups?

That huge `pie plate' gear will still get you close to 40mph because of the variable drive the bike has.I would say an exhaust mod would help,but wait for Ron to answer.

Re: Motobecane tune ups?

I have a '78 Motobecane 50V basket job I'm working on. Does your 77 fhave the variator clutch, or the fixed pulley? I'm assembling mine with the fixed pulley clutch, but I have the variator clutch as well.

Andrew Spoering wrote:

>

> I rececently got a '77 Motobecane 50v that's in beautiful

> condition. It wasn't running when I got it, but a new plug, a

> little cleaning, and a carb rebuild later and the thing is

> running awesome. However, I'd kinda like it to run a little

> faster (it's the 30mph model, and accually tops out at around

> 32-33). I know that with a 2-stroke engine you really

> shouldn't deconstrict the air intake or the exhaust for fear

> of messing up the balance of the exhaust/intake, and I'm

> pretty sure that even if I did that the gearing (that huge

> pie-plate of a gear) wouldn't allow greater speed anyway. So

> is there any way that anyone can think of that'll get me

> another couple mph out of it? Thanks!

Re: Motobecane tune ups?

Shotgun,don't take that variator pulley off there! That's what gives that bike power and versatility.And guys,that `V' in 50V means variable drive(variator equipped) so if it just says 50,it's probably not got the variator.

Re: Motobecane tune ups?

Ron Brown /

Andrew,

If you search the forum using Motobecane, Mixture, all words and go back several months, you will find a detailed description of how I tuned mine.

In a nutshell, I removed the air box and screen, leaned the main jet to optimum, then modified the air box to remove restriction to air flow. This got me an easy 5 mph.

Ron

Re: Motobecane tune ups?

Yep. But the original "V" motor has crank seal problems, so I've built a lower end together with the other motor which appears to be in great shape. The other lower end had a disassembled single speed clutch, so I may be stuck using that since I can't get the variator clutch off the other crank end.

I need a special clutch hub tool, and I don't have any that fit in the garage. I also don't have any source to buy one, so I may be stuck with the single speed clutch. I've tried everything short of damaging it including soaking overnight in penetrating oil and shocking the shaft with hammer; no luck.

I also may have to use the older pre-77 carburator, since the original post-78 is in really, really bad shape. I may not get the speed using a slower carb and clutch assembly, but hey, it oughta run! I've got new piston rings on the way.

Thanks for the advice. I've had this project only two days, but learning fast.

Re: Motobecane tune ups?

Ron Brown /

Try some of the suppliers in the resources section. I am sure I have seen a puller for about $15.00.

Ron

Re: Motobecane tune ups?

Andrew Spoering /

Thanks. I did the search and got some great ideas. I may have a problem getting to much more as I live in Denver CO at 5280 ft above sea level, so oxygen is tough to come by up here, but even 2-3 more mph will be nice.

In response to Shotgun's question, yeah, my Motobecane is the one with the variator. I think that all of the 30mph models are.

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