Gas mileage too low?

[Torques]

When I first got my Robins/Suburu motor new in mid August I was getting around 138 mpg. 2200 miles later I seem to getting around 114 mpg. I have a Robins/Subura eho53 friction drive system on my cruiser. I have run unleaded regular in it. Performance is good. I change oil around every 3-400 miles with Mobile 1. I have run some Seafoam thru it in case of some carbon buildup. Any ideas? Thanks.

 

[davidsis]

Bad gas milage

Maybe some adjustments on your carburator need to be made. Usually the vibration on engines will loosen up a screw on your carberator and make it burn more rich.

 

[Tom]

There are a bunch of factors that could play a role in this problem.

Tire pressure
Riding conditions
Riding style
Engine wear?
Drive pully wear?

You should tune your bike up and then try checking your mileage again. Maybe you didn't use the exact same amounts of gas when you checked the first time vs the last time.

 

[mrsaxman99]

how about replacing the spark plug?

 

[Torques]

The motor is only 4 months old with 2200 miles on it. Should a new spark plug be nccessary that soon?