Motorcycle Repair: kymco 500 cc exciting scooter, air filter system, fuel mileage

Question
Hi Wayne

I was wondering if you can help. I bought a 2009 500cc Kymco 4 stoke scooter (craborator). Its an awesome bike and I really enjoy the ride, but I was shocked to find out how heavy it is on fuel/ gas.

The guy that owned it before me was a bit of a biker type so he changed the standard exhaust to a type of racing exhaust, I am not sure if he messed with the needle/ carb to maybe make it go faster. I dont need speed, I need it to be cost effective to ride.

This bike is suppose to give good millage per tank. The problem is I have to run to the gas station every day almost to keep it full. It uses almost 3 times as much gas as my Honda 250 foresight scooter.

Before I have to sell this bike due to the fact that I cannot afford the gas anymore, pl can you tell me where to start looking to try and solve the problem.  

Thanks
Mike

Answer
Hi Mike,

There are a few things to consider.
One is the fuel tank is only about 3 gallons and the
bike normally gets about 50 miles per gallon.
That is only 150 miles per tank which might feel
like you are adding fuel frequently.

The stock exhaust is designed to have some backpressure
which can help to improve fuel mileage especially if the
engine is unmodified and the air filter system is also stock.
If the previous owner changed the air box, carburetor
or exhaust those could influence mileage.

The other thing that can hinder mileage on a acooter is
a worn drive belt or any rolling resistance like
dragging brakes or low tire pressures.

Your weight and climate can also factor in the fuel usage.

If you check the spark plug color it should be light brownish
color. If it is dark colored or black then the jets are either
too large or the air filter is plugged.
Also a faulty choke or enrichener can lower mileage significantly.

Decreasing the main jet can only be done if the plug is very black
most of the time as leaning the fuel mixture too much can cause
overheating and engine damage.

The carb slide needle clip can sometimes be raised to lean the
mid-throttle fuel mixture a bit.
By dropping the needles position  it leans the fuel/air
but may result in hesitation.

You want to have the bike running as lean as possible without the
spark plug getting too light colored which can cause harm.

The spark plug will always tell you what the engine is doing
so if it is a tan or light brown color the engine is running normally.
Running too much fuel would be indicated by a black or sooty plug color.

If the plug color is good then there is not too much you can change
other than check the belt etc.

http://www.verrill.com/moto/sellingguide/sparkplugs/plugcolorchart.htm


WS
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