Hoping someone has some two stroke wisdom to help me out. My girlfriend is starting out in the two wheeled world and has got an Adly Fox 50 moped cheap from a friend. Its a 2000 model but has hardly ever been used so runs well. However, while it pulls away fine, it has a definite flat spot and bogs down between 15mph and 25 mph, after which it pulls fine again to a heady 32 mph…
We don’t need it to faster flat out (yet), but I do want to try and get rid of this flat spot - if you hit a hill while you’re in it, it will struggle to get up it, either side, its fine.
I’m led to believe this may be down to the carb being restricted (correct me if I’m wrong). I think there may be washer of some kind in the carb that needs to be removed to help the breathing? I think there’s another step on the variator that mechanically restricts top speed, but I’m not too bothered about that yet - unless I need to be?
Any advice welcome, if I can just get rid of this bogging down it will be fine!
If it is a belt cvt bike then flat spots can arise from roller wear. It can be very noticeable on a two stroke 50 due to the lack of torque. A new belt and rollers can make acceleration much smoother and uniform. However, a 50 accellerating up a hill is never going to be fun!
BTW, I don’t think they are even the 5bhp 50cc mopeds are allowed to have. I think they are only 3.5bhp or something silly.
Hi Giuliano, well its only done about 3000kms so am hoping the rollers ought to be OK, could be them though I guess. The other thing is that the bogging down only really manifests itself once its warmed up, oddly, so I’m thinking induction / exhaust again.
It was stood for a long time and it took me a while to get it going - had to drain the tank and replace with fresh fuel etc. Its done about 100 miles since its been running again - am wondering if there’s a chance the carb could still be coked up a bit?
It is not uncommon for small two strokes to be “derestricted” in ways that do little to improve performance but create flat spots as people mess around with things like the exhaust without rejetting to compensate. The fact that when warming up it runs better does make it sound like it is a fuel problem.
As for restriction, there may simply be a CDI rev limiter. I notice the Adly website says -
“3. CAN THE 49CC SCOOTERS BE MADE TO GO FASTER?
As the importer we are not allowed to tamper with speed restrictions or emission controls. We can never recommend that anyone cut the green looped wire on the CDI to defeat the rev limiter.
There are performance parts available but any modification to the motor will void the warranty.”
Ah - nicely put by Adly, I hadn’t found that on their site, thanks.
That said I don’t really want it over revving or placing more stress on itself by doing the CDI thing, am just keen to make the best of what its got. Think I’ll have a fiddle in the carb see what I can find - also will check the exhaust as well.
Its probably just not a decent enough motor to have a linear delivery, but worth a try.
I have the same moped. Going to put new performance variator, clutch springs and torque spring. Checked exhaust and nothing there but can’t find the cdi unit to sort the green wire. Does anybody know where they are and what they look like on an adly fox year 2000
