Tank coating and issues thereafter

**I thought I posted this here before...but I forgot and with recent issues, figured I'd post here and get some ideas floating around from people that know these bikes**

I got my tank coated around this time last year...I forgot exactly what they used but it's cream colored.
Immediately afterwards I notice that when I fill up my tank and the fuel comes up the neck...I have to shake the bike from side to side for the gas to go down again. Air bubbles will come up and the gas level will go down.

So now my filling up process is:

-Fill tank till gas almost overflows...
-Shake bike side to side...
-Watch the gas bubble and go down a bit...
-Repeat till I lose my patience and cap it all off.

Why would coating the tank do this? Could they have possibly blocked something off?
What does the inside of the tank have that could explain this? Baffles?

Also...now whenever I fill up the tank I need to drive for a while before parking it. If I don't and I fill up and park the bike immediately afterwards, fuel will spill out of the cap.
I know this is from the heat from the engine heating up the gas....but I don't think this has ever happened before I coated the tank.

Is this a Tank coating issue?
...or a Gas Cap issue?
...or a me filling up too much issue?

 

You got me on the coating issue but yes, gasoline does expand quite a bit when it warms. My bike is always on it's side stand when I fill so it never really fills right up and I have never had any problems.. A 6th gen though

 

I have used the tank recoating in my landscaping machines and have never had a problem. I don't think it would be a problem in a bike either. I hope not cause the tank i'm working in is coated.

 

Kind of consider this a guess,but when the guy put the coating material in the tank,could he have possibly closed up the air vent orifice or the overflow tube !
With one or both of these tubes closed ,it could be a real problen to fill up and vent out all the air previously in the tank. eddie!

 

I don't dismount my bike to fill up (given the height of the keypad/nozzles/swiper dealio agree). I notice the same thing and I have no coating, but obviously I've a completely different bike with completely different tank geometry. However, if I fill the tank up with gas up to the neck, the gas will slowly empty into the empty space that's at the very top of the tank, above the lowest point of the inlet. If I shake the bike it goes faster, but it isn't 'necessary.'

 

A few things I should mention about the '86 VF500.

-You cant see directly in the tank....there seems to be baffles and such so that you can't see anything but the plate an inch from the filler hole.

-There is NO vent/drain for the gas tank. 2 holes...One that the Gas Cap covers...one that the Petcock goes into.

I assume that maybe a passage or baffle was blocked by the coating making things odd.

 

I think your deductions are spot on slow. Might have to drill/ bore out the vent holes somehow.

BZ

 

There are no vent holes on the '86 VF500 tank

 

Looking for education. Not questioning veracity.

How do you know it doesn't have vent holes? It must have some system.
On older cycles, it might be integrated into the cap. I'm not familiar with your model, but have various old engines around that have diaphrams or holes in the cap. You fill it with the cap off, though

 

Maybe the Cap is part of the venting system.....but the tank itself has no vent holes or overflow system.

So do I have a cap problem then?

 

is there anyway you can find out what type of coating the guy put in your tank? if its latex, some of it may have come off of the tank somewhere and may be trapping air which could cause your air bubbles. if this is the case i would have your tank recoated but this time using a product called POR 15, its an epoxy paint type coating that is permanent and is supposed to never delaminate from the surface of the metal, latex on the other hand can be dissolved with chemicals like mineral spirits and MEK

 

I think it was kreem or that Por stuff.

 

the kreem stuff is the latex and ive heard that it eventually breaks down, it should be white in color, the por 15 is like a gunmetal gray. ive never handled the kreem but por after it cures hard so i guess if you can feel the coating and its softer then you have the kreem

 

It's kreem then. :frown:

 

based on the fact that all of this started after you did the tank coating it is a good possibility that it is the problem... if you want to remove the coating from your tank get your hands on some MEK (methyl ethyl ketone) and it will dissolve the coating. if you do decide to do this be careful because mek is some nasty stuff, it works amazing but it very flamable, and extremely hazardous to your health so try not to breath the fumes or let it touch your skin. it attacks the central nervous system and make you dizzy and have bad motor coordination until it goes away. sorry for the disclaimer i personally hate using it even though i have to sometimes as an aircraft mechanic

 

Thanks. I don't think I'd wanna go and remove it all.

My problem is annoying but not that big a deal to go through all that trouble.