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View Full Version : How long does it take before gas gunks up your fuel system ?


WildKat
12-02-2004, 08:55 AM
I know its important to keep a full tank of good, high octane gas in your bike if you're gonna winterize, and of course use stabilizer as well.

But how long can a bike sit, before that gas breaks down enough to cause rust in the tank, deposits and gunk in the fuel lines, carbs etc.

Reason is, my old yamaha that I sold to my Father in law, hasnt gotten ridden much at all since about august and probably wont be until atleast next summer. I mentioned to him about keeping good gas in it, using stabil, etc.

trinc
12-02-2004, 09:03 AM
The current shelf life of today's fuels is pegged at about three months. After that, the additives begin to separate, the octane level drops, and the gas begins the process of ‘going bad' and varnishing fuel system components (including gumming up the carb).

this was lifted from another site - i had heard as soon as 6 weeks.

tim

jhugh
12-02-2004, 09:59 AM
If it was stored w/o any stabilizer in August and you aren't going to ride it until next summer I would drain the old fuel out of there and replace it with fresh gas + stabilizer. Run it to get the treated fuel through the lines and into the carbs then top off the tank.

Sta-bil claims that fuel starts to deteriorate in as soon as 2 months.
They also claim that treated fuel will last up to 15 months.

Matt
12-02-2004, 11:53 AM
If you live in the northeast or other cold regions, the gas is already treated with alcohol or something to reduce freeze problems. Stabil only seems to gum things up for me and I'll never use it again.

My bike sits for no longer than 90 days (winter) and it does better without Stabil, than with. Mixed according to the directions, I had to RING the daylights out of my bike to get it to clear out.

It took one year for the (untreated) gas in my generator to varnish - and man did it ever. The gas inside the float bowl was GUMMY. Simple drain the bowl and refill and it fired up on the first pull.

Living near Boston, our stock rotates quickly, (stations get tankers weekly) so I have no concern of aging gas in the pumps.

The CyberPoet
12-02-2004, 05:37 PM
A lot of it depends on the altitude, the relative humidity and temp, and the type of gas.

The higher you are, the faster fuel evaporates.
The dryer the air is, and the warmer the air is, the faster fuel evaporates.
Alcohol evaporates much faster than gasoline.
Custom "botique blends" of gas to match EPA and local regulations can alter the amount of varnish left behind and alter the evap rate heavily.

Gasoline in general contains up to 35% aeromatics by volume, and these will evaporate off first in an unsealed container often within a week or two unless treated with a fuel stabilizer (Kat gas tanks are not vapor-sealed except possibly on the California models). Fuel stabilizers help bond to the aeromatics to keep them trapped.

General rules:
The gas in the carbs, because it's exposed to air constantly and has a small container, gunks up in just a couple of weeks with no fresh flow. Always leave the drains open or at least run the carbs dry.

The gas in the tank on the 49-state model should be good for up to 70 days if it is NOT botique blend AND does NOT contain alcohol/ethanol AND does have a fuel stabilizer. Capping off the vapor vent tube from the tank if it has one will reduce the evap rate. If storing over 45 days, I recommend replacing the gas at the end of the storage period before firing up the bike -- for the cost of five gals of gas, it's easy peace of mind. Always keep a tank on the bike filled to keep air out -- air forms condensation, which drips into the tank, causing rust and increasing the rate of bacterial contamination.

Never use fuel with alcohol/ethanol in it for winter storage, as both can readily cause rust by being both hydroscopic (attracting water) and by inducing rust themselves.

For storage periods over 6 months, seriously consider draining the gas tank and leaving it open, hanging inside a garage or other "dry" storage. If you don't store the tank "dry", always insure that it is totally topped off with either fuel or oil (both will displace air which will prevent condensation -- oil is useful for very long term storage as it doesn't evaporate nearly as fast as gas, but needs to be rinsed out with fresh gas afterwards before filling up).

If you find rust, follow these instructions:
CyberPoet's How to Deal with Rust in your Motorcycle Gas Tank, at MotorcycleAnchor.com (http://www.motorcycleanchor.com/motorcycle/how_to/mc_tankrust.html)

Always use a fuel system cleaner after storage to clean out possible varnishes. Some varnishes will form strictly because of contact and lack of aggitation (and not necessarily from evaporation). The other big issue is that both gasoline and condensation can grow bacterial growths that eat the fuel and degrade it over time (other than evaporation, this is the biggest source of fuel contamination, and all fuels normally have some bacterial content -- we just burn through them fast enough for it to normally not be a factor). Someone out there makes a drop-in gas catalyst (a titanium-based one) that should, at least in theory, kill the bacteria, helping keep the fuel from degrading during storage due to bacterial contamination.

Cheers
=-= The CyberPoet

WildKat
12-03-2004, 08:43 AM
my bike will probably be sitting for the better part of atleast 90 + days before I "de-winterize" it for spring. I try to usually do it in late march. draining out the fuel is definately a safe idea. Thanks!

jhugh
12-03-2004, 10:46 AM
... I recommend replacing the gas at the end of the storage period before firing up the bike -- for the cost of five gals of gas, it's easy peace of mind.
That's good advice. I have noticed that the bike runs a little 'off'
when using stabilized fuel that's sat for 4 months. It clears right up
with the next fresh thankful. Use the old gas in the cage - it mixes with
what's in the tank and the cage won't know the difference.

As for fuel system cleaner, Chevron Techron comes highly recommended
especially for fuel injection systems. See if you can find the real stuff not
some other brand that says it contains some % of Techron.

illinoiskat
12-07-2004, 09:10 PM
For cold wet areas like Chicago and Boston, wont the tank rust if it is empty? I know the amount of 40 degree days with 100% humidity are high in November and December. I was allways told to fill the gas tank up in winter, since you can get a wet 40 degree day and then have a cold snap in the 20s and old that wet air in the tank sheds it water on the interior of the tank as it cools. And, whala you have water in the tank and the fuel lines and you have to put a can of heat in it to make it run right. I allways figured the moisture shedding action of wet air cooling into the 20s could also cause the tank to rust if you let it sit for months, but dont really know, since i normally leave the tank full.

SweetLou
12-07-2004, 10:43 PM
If you do leave fuel in the tank, I highly recommend the Chevron Techron. I would say it cleans about 75% of the carbs, running a full bottle thorugh. (Run three tanks through, using about a 3rd of the bottle each time) Worked very well on mine last season. As for the tank, I had the same understanding about the rust issue, but it also depends on how long it is sitting like that. Here winter can last from 4 to 6 months.

The CyberPoet
12-07-2004, 11:17 PM
And, whala you have water in the tank and the fuel lines and you have to put a can of heat in it to make it run right. I allways figured the moisture shedding action of wet air cooling into the 20s could also cause the tank to rust if you let it sit for months, but dont really know, since i normally leave the tank full.

Either leave it totally full, or take it off and leave it empty (taking it off lets it drain any condensation). Remember to go back and refill occasionally if it months -- to offset evaporation.

Cheers
=-= The CyberPoet