Motorcycle tank: Leaking fumes theory.

C

cbpayne87

Hey this is my first post, I didn't see an introduction area so. I have been working on a custom motorcycle project for the past year. At the moment I'm working painting the tank.
I was told about Harley Davidsons require a special paint or sealer to prevent later problems because their tanks are known for leaking fumes underneath the paint. Well I don't have a HD tank, but I have done some mods to my current one. I have Yamaha virago 920 fuel tank that had a flat flip top countersunk into the body of the tank. I found the right size exhaust tube piece at advance to braze on the tank so I could jb weld a brass collar for the new Monza style flip top could screw on to. I filled the countersunk with evercoat's z-grip. So my question is this something I need to remove and put some kind of special sealer around the brazed area? I have the inside of the tank sealed with KBS. Thanks brazin1.jpg

brazin2.jpg

brazin3.jpg
 
SPI epoxy on brass before any other products, clean it well to make sure there isn't any traces of flux, I usually spot blast stuff like that.
 
Thanks Bob, but im not painting that brass collar. I'm going to jb weld that collar onto that exhaust pipe that I brazed onto my tank. Now the exhaust pipe will be painted an I've clean up the flux hopefully good enough. There body filler in that spot now. I'll post a pic of it when I get home. Thanks for commenting.
 
ok i do this stuff everyday and may be able to help. first question....concerning that flip top gas cap, where does it vent? harley style caps destroy the paint because the cap breathes and the raw paint edge is exposed to gas fumes and many times actual gas when filling because its right there on the corner before it drops down into the tank. with your pipe sticking up out of the tank it doesnt appear that you will have an issue unless your cap is vented in a way where its blowing fumes down on the paint where it butts up against that brass/gold ring. what is very important with this stuff is that you dont use any 1k products like self etch primers and you add catalyst to your basecoat. this will help resist lifting greatly. epoxy primer should go on all bare metal, then filler. if you would like to seal that paint edge anyway when your done you will use a novalac epoxy. its super chemical resistant and used as a tank liner. not sure what kbs is but the epoxy is what you should have lined the tank with as well. if the kbs isnt an epoxy coating that required a catalyst then if i were you i would remove it all. you can get the epoxy from www.caswellplating.com. it is their fuel tank sealer kit. if the kbs is anything like kreem or the por stuff its pretty much junk and will cause more problems than it corrects. i have never seen a tank in my life where kreem was used and it wasnt peeling and rust forming under it. chips and bit come off causing fuel blockages. its terrible. the novalac stuff is also immune to the ethanol in the fuel.
 
Jim C;30145 said:
ok i do this stuff everyday and may be able to help. first question....concerning that flip top gas cap, where does it vent? harley style caps destroy the paint because the cap breathes and the raw paint edge is exposed to gas fumes and many times actual gas when filling because its right there on the corner before it drops down into the tank. with your pipe sticking up out of the tank it doesnt appear that you will have an issue unless your cap is vented in a way where its blowing fumes down on the paint where it butts up against that brass/gold ring. what is very important with this stuff is that you dont use any 1k products like self etch primers and you add catalyst to your basecoat. this will help resist lifting greatly. epoxy primer should go on all bare metal, then filler. if you would like to seal that paint edge anyway when your done you will use a novalac epoxy. its super chemical resistant and used as a tank liner. not sure what kbs is but the epoxy is what you should have lined the tank with as well. if the kbs isnt an epoxy coating that required a catalyst then if i were you i would remove it all. you can get the epoxy from www.caswellplating.com. it is their fuel tank sealer kit. if the kbs is anything like kreem or the por stuff its pretty much junk and will cause more problems than it corrects. i have never seen a tank in my life where kreem was used and it wasnt peeling and rust forming under it. chips and bit come off causing fuel blockages. its terrible. the novalac stuff is also immune to the ethanol in the fuel.
Click to expand...


Amen brother.
 
Hey Jim C I'm not really sure how the new cap will exhaust out fumes. I called the kbs tech, I wasn't told what the makeup of the product is but that it is stronger than epoxy. Now I don't know how it compares to caswellplating stuff, which I have heard was good stuff, but I know for a fact its stronger than that kreem kit. I have a kreem kit for sale... any takers? I want show quality on my paint job but didn't have the knowledge to know not to put body filler on bare metal. Even the evercoat tech said to put it on bare metal and spray etching primer on top. Well I learn the hard way not to use etching primer, I cracked up my 2k. Now I'm going back and sanding all the cracked 2k and etching primer off. I'm leaving the body filler on but will spray over it with the SPI epoxy. Though first I will clean the etching primer off the body filler two to three times with some harsh wax and grease remover then let the tank sit out in the hot sun for a day. Thanks... Collin
 
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