Does running on the speed limiter waste fuel ? By keith77rwb (Read 774 times)

[keith77rwb]

Hi Everyone.

Bought my daughter a 49cc moped for her 16th (Here in the UK you can ride a 49cc moped at 16, 125cc at 17, car at 17 if you can afford the insurance). Also here in the UK, mopeds are meant to be limited to 28mph.

The limiter works with a fairly soft cut-off so I am not clear if it is cutting the ignition or the fuel supply.
Now - if you just cut off the spark are you still pushing fuel through the engine (carburettor fed) ? i.e., wasting it ? and if not, why not ?

Note I am not asking how to disable the limiter, just should you drive just below the limiter, or does it make no difference just to keep the throttle wide open the whole time.

Cheers, Keith

[alleyoop]

The CDI cuts off the Ignition and drops the rpms on the motor. Now depending on what type of carb is on there it may waste some fuel. If the Carb that is on there has the Throttle Cable going into the top of the carb that type of carb would cause some gas to be wasted. Reason is that type of carb connects directly to the Slider which has the Needle attached to it and as long as your holding the throttle wide open it is allowing air and fuel to be sucked in. But since the CDI is cutting off the Spark to the Spark Plug it is not burning it efficiently.

On the other hand if the Carb on there is a CVK carb which operates with Vacuum then when the RPMS drop the Cylinder with the Needle ALSO drops cutting off some excess fuel from being sucked out.

But in either case the waste is minimal. A motor uses more gas when run at high RPMS speeds. So if you de-restrict and allow for higher rpms it will use more gas. Works just like a car the faster you go the more gas you use, if you go at slower speeds you use less gas.
Alleyoop

[prodigit]

If it does use gas, you'll hear the difference, of holding the throttle just before the limiter kicks in, and going WOT. the engine should sound different, with an occasional exhaust hiccup.

I do believe that most of the time, in europe, the scoots are mechanically limited, not electronically.

But also mechanical limitations waste more fuel than limitation free.

What you could do is open the throttle just under the limitation, and you'll not use more fuel than when you don't have the limiter on.