Oxygenated Fuels; Emission Control System Information - Yamakoyo YK250 Owner's Manual

TECHNICAL & CONSUMER INFORMATION
Even with carburetor modification, engine horsepower will decrease about 3.5% for each
1,000-foot (300-metre) increase in altitude. The effect of altitude on horsepower will be
greater than this if no carburetor modification is made.
NOTICE
When the carburetor has been modified for high altitude operation, the air-fuel
mixture will be too lean for low altitude use. Operation at altitudes below 5,000
feet (1,500metres) with a modified carburetor may cause the engine to overheat
and result in serious engine damage. For use at low altitudes, have your
servicing dealer return the carburetor to original factory specifications.

Oxygenated Fuels

Some conventional gasolines are being blended with alcohol or an ether compound.
These gasolines are collectively referred to as oxygenated fuels.
To meet clean air standards, some areas use oxygenated fuels to help reduce emissions.
If you use an oxygenated fuel, be sure it is unleaded and meets the minimum octane
rating requirement.
Before using an oxygenated fuel, try to confirm the fuel's contents. Some areas require
this information to be posted on the pump.
The following are the EPA approved percentages of oxygenates:
ETHANOL (ethyl or grain alcohol) 10% by volume
You may use gasoline containing up to 10% ethanol by volume.
Gasoline containing ethanol may be marketed under the name "Gasohol".
MTBE (methyl tertiary butyl ether) 15% by volume
You may use gasoline containing up to 15% MTBE by volume.
METHANOL (methyl or wood alcohol) 5% by volume
You may use gasoline containing up to 5% methanol by volume, as
long as it also contains cosolvents and corrosion inhibitors to protect
the fuel system. Gasoline containing more than 5% methanol by volume
may cause starting and/or performance problems. It may also damage
metal, rubber, and plastic parts of your fuel system.
If you notice any undesirable operating symptoms, try another service station, or switch
to another brand of gasoline.
Fuel system damage or performance problems resulting from the use of an oxygenated
fuel containing more than the percentages of oxygenates mentioned above are not covered
under warranty.

Emission Control System Information

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