MPG Drop

[m_stock10506]

I'm going to share this observation. Some may find it obvious, but I've been riding Airheads for 26 years and just put this together. Dropping fuel efficiency. I noticed on both of my bikes (a '74 and '84) that over the last month or more my MPG was dropping. Not dramatic, but down about 3 mpg. I checked maintenance records and saw that carb floats were OLD. Ordered replacements. R100, went back up to 42.8 mpg (over 250 miles), and the 60/6 went to 51.5 from 48. You don't have to wait for gas to leak all over your boots to realize it's time to replace the floats. Note that the replacements from EME were sealed plastic floats, not the traditional foam that I was expecting.

 

[20774]

Snowbum has reported on this and was weighing his floats. Do you have any numbers of "bad" and "good" floats as to their weights?

 

[stevenrankin]

One of the other reasons for mpg drop is just wear and tear on the carb needles and jets. A couple of years back I started having gas mileage drop off. The carbs had a large number of miles on them and visually the needles look good but, looks can be deceiving. St.

 

[m_stock10506]

Do you have any numbers of "bad" and "good" floats as to their weights?

No I don't. And I didn't bother to try the method of putting them into a container of gas to see how much of the float stayed above the top. The new floats from EME should show gas trapped inside the float if they start to leak, since they are translucent.

 

[20774]

Do you have a gram scale? Maybe you could measure the old ones. And maybe call EME and ask them what their new ones weigh?

 

[m_stock10506]

Maybe you could measure the old ones. And maybe call EME and ask them what their new ones weigh?

Kurt. Completely different products. Old OEM floats are foam, EME shipped floats are plastic. Any weight difference between them makes no difference.

 

[20774]

I thought it was all about buoyancy which depends on weight?

My R69S, it came with original brass floats, hollow on the inside. Vech at Bench Mark Works engineered a plastic float to replace the brass which had a tendency to crack, letting the fuel inside. The weight of the brass and plastic floats were the same.

 

[stevenrankin]

They changed to the foam floats, then to the sealed floats. I believe the newest floats are alcohol proof, they came out maybe in the late 80's? St.