Seafoam??

[csnyder993]

I am so glad that this question spawned such a lively, informative "discussion".  Thanks again for the good input.  

I've had this conversation on a motorcyle list also, and have copied two of the more informative pieces of information below:

All gasolines are very complex mixtures of hundreds of hydrocarbon
components (plus oxygenates these days), and plus a mix of additves to allow
the fuel to meet all specifications. Most of the hydrocarbons are very
stable when stored, but certain hydrocarbons, particularly the  chemically
unsaturated ones like olefins and certain others, like to react with each
other to form polymers. These polymers are the "gummy" material that you
find in old gas cans or in plugged up carbs or injectors.  All gasolines
sold legally (at least here in the USA) must have enough additives to slow
down this formation of gums during the expected lifetime of that gasoline.
There is a lab test which via heat and air accelerates this gum formation,
and passing the lab test means the gasloine  meets the stability
specification. But it doesn't prevent gums, it only slows it down, so long
term storage may require additional stabilizer, like the red StaBil that we
can buy in most stores that sell that sort of thing.

A couple of things accelerate gum formation, besides heat.  Air and a low
fuel/surface area ratio. Those are the main reasons that a full tank is
better than an almost empty tank. Plus, excluding air also excludes
moisture. However, in small places, like carb bowls, carb passages, or F.I.
passages, there is a relatively LOW fuel/surface area ratio, which gives
proportionally more sites for initiating polymerization.  That's the
greatest value of StaBil, preventing gum formation inside the small
passages, and that is why running the engine after addition of the
stabilizer is so important.  However, forgetting about stabilizer and riding
at least monthly will do an even better job!!

Regarding hard starting after storage. That has nothing to do with the
chemical stability of the fuel.  Even without any stabilizer, the
composition of the bulk of the fuel will change very little, and the octane
will remain virtually the same.  However, a couple of things may happen.
During the fall and winter, gasoline has more butane added to increase the
vapor pressure. This is to allow your car or motorcycle to start on a cold
morning. Without the butane, there would not be enough vaporization of the
gasoline.  So, in storage, much of the butane can evaporate off, making
starting in the springtime very difficult. If that is happening you would
notice a lower fuel level in the springtime.  Spraying some starter fluid
into the intake system can overcome this.


 

 

 

Seeing that I already have a Bultaco Streaker in my basement, I doubt my wife would be very understanding about another wheeled vehicle in the house.

But one bit of advice I've found to be true. Stable (sp?) fuel stabilizer hasn't done a very good job for me. The best trick (assuming your bike doesn't have a catalytic converter is to run out to your local rural airport and but some low-lead av-gas. It's got a great shelf life, smells great when burnt - 2nd only to Castor oil - and doesn't leave all the little bitty holes plugged up in your fuel system. And I don't think it melts polyester fuel tanks either. Just a thought although I am sure some will comment.