Tank repair?

[wence]

I have realised now why there was so much fine silt in my tank and why the carby and petcock keep getting clogged with silt and make the bike starve of fuel.
The reason is that where the return for the fuel cap(Indented portion) and thread for the cap meet I have a small split.
I found this by chance as I was trying to check if there was much crap in my tank. I tipped the tank( off the bike of course), and had fuel up just up to the inside of the lip.Fuel began seeping out .I checked again and found that the threaded portion has a split which I assume would suck in water and dirt that sits in the hollow around the cap. This is why whenever it rains my bike runs fine then starts to splutter(water in the fuel). I have checked after each wet race and there was water in there.
Anyway , that is the problem.
Now I need to know :
1). Has anyone had a similar problem?
2). How do I fix the split in this location?

I have tried silicon which lasts for a little while until the petrol gets into it.
I have tried that metal kneaded gear that is petrol safe but it did not seal the leak.
I am thinking some sort of plastic weld or something???
Any help would be appreciated,
Thanks Mark

 

[einsteingarage]

I have a clarke oversized tank that has a crack, so I am looking for a solution also.

I think I am going to try the plastic welding. Although a friend did suggest the flexible epoxy used to resurface the bottom of skis.

 

[wence]

Would that work?
Is it resistant to fuel?
Maybe resin( as in surfboard)?
Cheers Mark

 

[einsteingarage]

Resin sounds right. He seemed to think it would work.


I have adjustable heat guns at work that can go to 1000 degrees F I may just buy some plastic welding rods and give that a go.

Anyone know what type of plastic the tanks are made from?

 

[HydroDog]

I believe tanks are made from polyethylene. I have heard of guys using repair kits for kayaks.
I would think if you drilled a small hole at each end of the crack to stop it from cracking farther and heat weld it with a small butane torch and use a piece of old fender plastic for filler material if needed would work. Just make sure you rinse out the tank and fill with water up to close to the point of repair before starting with the heat.

 

[widebear]

P tex stick for repairing snow ski bases. You light it on fire and drop a flaming drop of molten plastic into the repair.Caveat not required for obvious reasons.

 

[Eric K]

I repaired a leak on a KX80 tank with JB Weld. May be worth a try. Sand and clean well before using JB.

 

[jostby]

P tex stick for repairing snow ski bases. You light it on fire and drop a flaming drop of molten plastic into the repair.Caveat not required for obvious reasons.

I have repaired several different types of plastic things this way. Get the same type plastic and light it with a torch. Then let it drip in the crack and it melts in to the crack and makes a fair repair. Never used the P-Tex sticks, good idea.

Gas impregnates the plastic though, that may cause problems making any type of repair. Because of that I don't think even a high quality epoxy will last very long.

 

[wence]

I ended up using a heat gun, heating the shroud plug area on the tank and then heating the litlle plug that had come out of the hole until it was very soft and tacky. Kept heating both until they were about the same and then pushed it in the hole.
I used the end of o socket wrench to smooth it and blend it together.
Left it for a while and then screwed the shroud back on .... all ok so far, haven't ridden yet though.
As for the thread split... I rechecked the leak and the split was fixed( all be it temporarily), with quick steel. The reason it was leaking was because I had so much in the base of the threaded section that the cap could not seal.
Hopefully all fixed now.
Thanks for your replies,
Mark

 

[einsteingarage]

That's good news Wence. Hopefully it is permanent

I am going to go the heat gun route.