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Topping off gas

3K views 12 replies 10 participants last post by  xantonin 
#1 ·
Hi
This time of year in the north east it starts getting into the 40s at night. I've been told by a few people to top off the gas after riding so that the bike doesn't collect condensation and rust. I've also read that filling the tank too much can cause a vapor lock.

I was wondering what people consider topped off. I've been filling to the bottom of the collar while the bike is on the side stand. Does anyone fill it any higher than that.

Thanks
Joe
 
#4 ·
If you know you'll be out again within a week or two you can fill up as needed. If your taking advantage of a nice day then letting it sit for a while I would add stabilizer and fill to the bottom of the neck collar. When you stand the bike up right you'll see how the gas comes up to the bottom of the gas cap.
 
#5 ·
a week or two? that's at least 2-4 tanks down the road.. wher r u Alaska?
topping off tanks; I don't fill up when the motor is hot and putting it up for the nite. but then it doesn't get to single digits here.. ever?
if you keep a short wedge of 2x4 in yor saddlebag, you can stand yor bike near uprite for topping off and checking Erl.
full up to the bottom of the gas bung is at least a half gallon shy of full. on my v2k, I could squeeze perty near a whole gallon more in that air gap that resides top of the tank. you have to wait, jiggle and burp it. but can be done. all tanks are same. big air pocket on top.
I do this when I am actually riding.. and particular far long distance.. every extra bit of fuel is comfort out in the boonies.. I go ther a lot. poncho
 
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#7 ·
I'm with Bill. Folks that pretend gas does not expand often have gas cans with round bottoms, or major gas leaks. The best way to prevent rust in a gas tank is to ride that baby often. Next best is to ride as often as you can without invoking frostbite or divorce. Tom
 
#11 ·
I used to know a guy that would add a VERY low ratio of 2-cycle oil to his gasoline on his car periodically to keep the fuel system lubricated. We're talking like 200:1 or even less.

Anyway, I bring this up because it might not be a bad idea to help prevent rust in the gas tank. You'll have to play with the ratio. The manual says if you are storing the bike to drain the tank and add some motor oil and roll it around. So, I see no reason 2 cycle oil would be any worse. If anything, it would be better.

I'll probably try this myself. Just keep in mind the bike will run a slight bit leaner.
 
#12 · (Edited)
Rather than experiment, just stick with what works.

For long term storage, you have two options. Drain the fuel tank and carbs, and spray the carbs with fogging oil, and pour some motor oil in the fuel tank and swish it around to coat the walls.

OR

Add sta-bil or seafoam to the fuel. Drain the carbs and add fogging oil. Keep the fuel tank full to prevent internal corrosion.

What you do NOT want is any combination of unstabilized fuel or fuel tank metal exposed to moisture and corrosion.

Your friend with his two cycle oil is doing exactly nothing. The fuel system doesn't "need" lubricating and it's DESIGNED to work with gasoline. A fuel stabilizer can help prevent the fuel from varnishing with long term storage. Gasoline is also a solvent, meaning any tiny bits of two-cycle oil that might cling to some component would then immediately get flushed out and burned in the engine by the gasoline. I can't even begin to fathom what your friend thinks is "happening" by adding two cycle oil to the fuel tank, other than risking his fuel pump and injectors (a carbed engine can tolerate oil, such as fogging oil, in ways that a high pressure fuel injection system cannot) and wasting some money. Absolutely nothing positive will happen or could happen.

I'm genuinely scratching my head as to why someone things the internal fuel system needs "lubricating" and why they think oil is what'll lubricate it. Take some motor oil, just a dab (which is an order of magnitude more than the oil that would actually touch the fuel lines in that situation), and pour some gasoline on it. No more oil. Even if he ran a straight up 40:1 two cycle oil setup and, through some miracle, his fuel system survived such abuse; the very next tank of gas would completely break down and dissolve all of the oil within the first few minutes of driving. (And then it would run MUCH better because it wouldn't have the added FRICTION and TENSION of oil doing the OPPOSITE of lubricating. Fuel running through tubing is not the same as two metal parts rubbing against each other). No offense to your friend but that's just... the weirdest thing I've ever heard of and kind of the strangest example of the at-home chemist I can think of. It's not uncommon for people to want to mix up magic potions in their oil and gas tank to give some perceived advantage (usually, they are doing more harm than good); but that one takes the cake, ha!

AND, if the idea is to add oil to the fuel to protect the tank; again, gasoline is a solvent. If the tank is full, it will not rust. If the tank is half-full with oil and gas, the top half could still rust because no matter WHAT is in the tank, if it isn't touching the walls of the tank, it can't protect it. The manual suggests motor oil because STRAIGHT motor oil not in the presence of a solvent like gasoline will cling to the walls of the tank. However, leaving the tank full is just easier because when the walls of the tank are covered with gasoline, moisture won't harm it then either.
 
#13 ·
Your friend with his two cycle oil is doing exactly nothing. The fuel system doesn't "need" lubricating and it's DESIGNED to work with gasoline.
Well, I did originally state he did this for a car, which would have a fuel pump (which is not the case with gravity fed motorcycles).

The idea was also for top-end lubrication, something more critical on older vehicles, which I believe this guy owned.

LUBRICATION
 
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