A petrol (gas) question

[Cormanus]

Whenever my bike has been sitting around with fuel stabiliser in the tank while I've been away, it always burns through that tankful when I get back on it. I don't run the bike any differently.

An example: my average MPG in US gallons is 44.11. When I ran the bike with stabiliser in the tank after it had sat for 5 weeks, I got 28.48.

Any ideas? Or is this normal?

 

[Banned_imp]

I have noticed this as well on my Harley, I always have to remember in the spring that I don't have the normal range on the 1st tank of the season - the fuel gauge is fairly useless on the older models.

 

[Gumby 1100_imp]

Same here; My first tank of stabilized fuel in the spring burns off pretty fast with terrible economy.

But, I guess that is preferable to having the fuel tank, pump and injectors all gummed up with spoiled and gelled fuel.

 

[Rocky_imp]

Interesting topic.
I have never taken any particular notice of this because, after sitting for nearly six months over the winter, I burn through the old stabilized gas as fast as I can to get rid of it and don't care what mileage I get.
I just want it burned and gone so I can start the season fresh.
Unless I'm away for some reason, none of my bikes sit unused for much more than a week during the summer so I don't bother to use a stabilizer.

Same here; My first tank of stabilized fuel in the spring burns off pretty fast with terrible economy.

But, I guess that is preferable to having the fuel tank, pump and injectors all gummed up with spoiled and gelled fuel.

100% agree with that

 

[use2b_imp]

have any of you tried some seafoam fuel treatment after that 1st tank ?
that stuff cleans my carburetor bikes and keeps them running great with little to no maintenance

 

[stateboy_imp]

have any of you tried some seafoam fuel treatment after that 1st tank ?
that stuff cleans my carburetor bikes and keeps them running great with little to no maintenance

I use Seafoam exclusively over other stabilizers. I just don't have the mileage racked up on my bike like many of you do so, I am not in a position to give a competent opinion on what the mileage outcome is. I can say I try to use it year around and get over 50 mpg (but that's with fresh gas).

 

[the Ferret]

The longest time any of my bikes have sat in recent years is 3 weeks lol. However " just in case" I start Seafoaming in November and carry it thru until March.

 

[LongRanger_imp]

I use Seafoam or Stabil (whatever I have lying around) beginning in October. The bikes fire right up in April. In good years, I'm able to get in a ride in February or March, but I can't always count on that. Never had any issues with fuel or batteries.

 

[Rocky_imp]

I've heard a lot about Seafoam, but I don't think it's available around here.
Stabil is readily available, but the next time at the auto parts store I'll scan the shelves for it.
That said, I've had good results with Stabil for 25 years in carb and injector bikes so I'm not unhappy with it.

 

[Cormanus]

I have used only Stabil as I've not seen seafoam in Australia. My bike doesn't usually sit long enough to bother with it, but I've used when I've had to be away for more than a couple of weeks. Like Gumby, I'd prefer the poor economy on one tank to the gnome getting gummed up.

Interesting that others notice the same thing. Thanks for responding.

 

[alprider]

omg...this kind problems i like to have too....smile.... i guess i prefer our gas here

 

[Slow Poke_imp]

If you can find some alcohol free gas in your area, it lasts a lot longer without gumming up. Over the winter is no problem. I get a few more mpg's when I use it, added bonus.

 

[tinboatcapt_imp]

I had never thought the poor mileage on the first tank after winter storage was due to the fuel stabilizer. In this neighborhood, winter storage is four to six months. I had always chalked it up to evaporation. Pump gas has a measurable percentage of 'low boilers' that evaporate fairly quickly. Less fuel burns to get to the "I need gas" point on the gauge. Compounding that is that the remaining mix is ... well ... 'gunk'. On my personal bikes, I have been known to drain the tank and pour the 'gunk' into my pickup truck.

A trick we used when we had demo bikes and others stored at the dealership*, was to use 100 octane avgas. It's not legal for street use, but enough to keep the system wet and start a bike for a customer. (Also, the bike will run REALLY well on it.) Avgas is specified to remain stable for six months. Those 'low boilers' could be a problem in an aircraft at higher altitude by causing vapor lock. Something not of great concern in a vehicle.

*A short stint as Sales Manager.
jim

 

[flynrider]

I had never thought the poor mileage on the first tank after winter storage was due to the fuel stabilizer. In this neighborhood, winter storage is four to six months. I had always chalked it up to evaporation. Pump gas has a measurable percentage of 'low boilers' that evaporate fairly quickly. Less fuel burns to get to the "I need gas" point on the gauge. Compounding that is that the remaining mix is ... well ... 'gunk'. On my personal bikes, I have been known to drain the tank and pour the 'gunk' into my pickup truck.

A trick we used when we had demo bikes and others stored at the dealership*, was to use 100 octane avgas. It's not legal for street use, but enough to keep the system wet and start a bike for a customer. (Also, the bike will run REALLY well on it.) Avgas is specified to remain stable for six months. Those 'low boilers' could be a problem in an aircraft at higher altitude by causing vapor lock. Something not of great concern in a vehicle.

*A short stint as Sales Manager.
jim

Avgas is extremely stable compared to auto fuel. Unfortunately, using it in a modern vehicle could be disasterous. It gets its high octane from large amounts of tetraethyl lead, which will destroy catalytic converters and oxygen sensors in short order. Even in older bikes, long term use in an engine that doesn't have high compression pistons will eventually lead to unburnt lead deposits gumming up the valves.

That said, I used to use avgas quite successfully in my old Mercury convertible with a high compression V8 (originally spec'd for 98 octane auto fuel). Ironically, at the same time I had to burn 87 octane auto gas in my old Cessna with a low compression engine (originally spec'd for 80 octane avgas).

 

[Stichill]

I've always attributed the drop in winter mileage to evaporation...never considered if the stabilizer had an effect. I use Seafoam like several others here.

Just as a point of discussion, not criticism...I don't think it's strictly legal to use untaxed offroad fuel in road-going vehicles. Not that anyone would ever check a motorcycle for taxed fuel. But, for example, using red-dyed home heating oil in a road-going diesel that's supposed to be burned taxed green-dyed diesel is a no-no.

 

[tinboatcapt_imp]

Flynrider warns that leaded gas (avgas) harms catalytic converters and o2 sensors.
Stichill points out that it is illegal to use untaxed avgas on the roads.

It is true to both counts: it is illegal to use avgas on the road, and it does contain some TEL. For the shop we used a very small amount in the tank just to keep the tank and system 'wet'. That small amount would be highly diluted when the tank was filled with taxed, government approved petrol. The fuel is 'low lead' and not as heavily laden as the leaded gas of the 60's.

The small amount was sufficient as the bikes were stored inside heated space so condensation was not a problem. They all fired right up when needed in the spring.

I don't suggest that you regularly run the bike on anything but what can be dispensed from a station pump. Sorry about the confusion. One low mileage tank fill, at the start of the season isn't critical.
jim

 

[Stichill]

Something interesting, tinboatcapt, that I remember from a research paper I wrote on the detrimental effects of low-lead gasoline on engines designed to run with leaded fuel, is that the octane-boosting properties of TEL are not linear. There is a relatively large octane boost for the initial amounts of TEL, but further octane increases require ever-higher concentrations of TEL. So that seems to fit your impression that a small amount of leaded avgas would have a larger-than-expected effect on the "virgin" unleaded fuel in the tank.

 

[flynrider]

Flynrider warns that leaded gas (avgas) harms catalytic converters and o2 sensors.
Stichill points out that it is illegal to use untaxed avgas on the roads.

It is true to both counts: it is illegal to use avgas on the road, and it does contain some TEL. For the shop we used a very small amount in the tank just to keep the tank and system 'wet'. That small amount would be highly diluted when the tank was filled with taxed, government approved petrol. The fuel is 'low lead' and not as heavily laden as the leaded gas of the 60's.

The small amount was sufficient as the bikes were stored inside heated space so condensation was not a problem. They all fired right up when needed in the spring.

I don't suggest that you regularly run the bike on anything but what can be dispensed from a station pump. Sorry about the confusion. One low mileage tank fill, at the start of the season isn't critical.
jim

Actually, it's called 100LL (low lead) because it has less TEL than the green 100/135 avgas sold in the 60s and 70s (primarily for huge supercharged radial airliner engines). The TEL content of 100LL is about 10 times the amount found in the old leaded regular auto fuel.

I agree that heavily diluted and not used as a regular fuel, it's unlikely to damage exhaust components. I only posted as a warning to those who might try filling up their tank with 100LL avgas as a storage strategy.

 

[tinboatcapt_imp]

Flynrider warns that leaded gas (avgas) harms catalytic converters and o2 sensors.
Stichill points out that it is illegal to use untaxed avgas on the roads.

It is true to both counts: it is illegal to use avgas on the road, and it does contain some TEL. For the shop we used a very small amount in the tank just to keep the tank and system 'wet'. That small amount would be highly diluted when the tank was filled with taxed, government approved petrol. The fuel is 'low lead' and not as heavily laden as the leaded gas of the 60's.

The small amount was sufficient as the bikes were stored inside heated space so condensation was not a problem. They all fired right up when needed in the spring.

I don't suggest that you regularly run the bike on anything but what can be dispensed from a station pump. Sorry about the confusion. One low mileage tank fill, at the start of the season isn't critical.
jim

Actually, it's called 100LL (low lead) because it has less TEL than the green 100/135 avgas sold in the 60s and 70s (primarily for huge supercharged radial airliner engines). The TEL content of 100LL is about 10 times the amount found in the old leaded regular auto fuel.

I agree that heavily diluted and not used as a regular fuel, it's unlikely to damage exhaust components. I only posted as a warning to those who might try filling up their tank with 100LL avgas as a storage strategy.

Actually, it's called 100LL (low lead) because it has less TEL than the green 100/135 avgas sold in the 60s and 70s (primarily for huge supercharged radial airliner engines). The TEL content of 100LL is about 10 times the amount found in the old leaded regular auto fuel.

I agree that heavily diluted and not used as a regular fuel, it's unlikely to damage exhaust components. I only posted as a warning to those who might try filling up their tank with 100LL avgas as a storage strategy.
Interesting. My chemistry is polymers, and it's ancient knowledge.
jim