Installed New Gas Tank...Beautiful

[joe camarda]

Several weeks ago I purchased a used tank and had it painted a beautifullly bright orange. Pulled off the Coppa tank and installed the orange one. I immediately noticed that the bike ran a lot faster (not really) and after 5 minutes I noticed an odor of....of gasoline. Checked the bike visually and saw a constant 5 second interval drip from the lowest edge of the right front side of the tank.

 

Okay, figured I hadnt tightened averthing that I should have tightened so I pulled the tank and did that, STILL the dang drip!

 

I was able to reach under the tank while the bike was running and could feel the connections at the two nipples. No leak there.

 

No leak at the pump/filter hole.

 

Turns out the leak is from the inside right front of the tank where I guess it suffered some "tank-suck" induced stress. Does anyone know if this location is prone to failure from "gas-tank suck".

 

Edit: I'm not sure this is a "Technical Topic" and I actually meant to post in the "24/7 Forum"

[jrt]

Can you take it to someone who does plastic welding? I'm not sure the paint job will live through it, but if it's underneath, then just a touchup might fix it.

 

Sorry to hear your bad news.

[joe camarda]

Hi Jason. Thats the plan now.

 

On the upside I did take the oppportunity to (1) remove the tip-over valve (maybe not a good idea considering my run of bad luck lately), and (2) install a BMW quick disconnect in the line next to the tip-over valve line.

 

So...off to the races for the plastic weld.

[JoeV11]

You can save your paint by applying a gas tank sealer to the inside of the tank. POR-15 makes a great product, it worked on two old tanks that I used it on. Best of all you won't have to remove any rust from the inside of the tank! Joe

[joe camarda]

Joe...thanks for the advice. I just visited POR15 website and it looks like what I need. However, the site did NOT mention using the "US Gas Tank Sealant" on plastic tanks.

 

Have you used it on plastic tanks?

 

Also, any recommendations re the use of a "re-inforcing material" for exterior applications? I will probably patch from inside and outside as well.

 

Thanks again

[jrt]

I'm pretty sure that POR won't bond to the tank, which is made from a fairly inert material. The POR might make a tight seal against the tank for a long time, but I am skeptical of it as a final solution.

I'm speculating here, but the tank is probably polypropylene, which is one of the cheapest and most inert polymers. There's just no way to chemically get a hold on the backbone. Very similar to plastic milk jugs. You could try some POR on a milk jug as a test run, I suppose.

 

Joe C.- if you weld the tank, there's no need for reinforcing material. It's welded- a done deal- two pieces made into one again.

[DeBenGuzzi]

too bad I can't use the Coppa tank on my bike, I'd try and take it off yer hands. 2 problems wont fit and wont connect without some mods. basically wont fit period as I have the shorty frame.

[Paul Minnaert]

the leak might come from an accident. When the forks slaps againgst the tank, it will leak there. Welding might not be easy.

[waspp]

Welding isn't the only option, you can grind out the offensive area and use the correct expoxy for a repair. Most shops should be able to fix it, also if you just zip tie your tip over valve to stay in a vertical position you won't build tank pressure.

[joe camarda]

Well, unfortunately it doesnt look like POR 15 is an option. The company rep said that it has been used on fiberglass, but he couldnt recommend it for plastic.

 

Plastic welding is another choice (but not yet my decision). The welder I contacted needs to know specifically what kind of plastic my Moto Guzzi tank is made of.

 

Does anyone know? Or know where I can go to to get this info?

[Paul Minnaert]

the material is printed in/on the bottom I think.

[joe camarda]

Thanks Paul, I'll check that when I get home.

[joe camarda]

I located the source of the leak. It is a hairline crack starting at the most forward point of the front inner radius (next to the right side of the steering head), extending rearwards .5 inches and approx parallel to the bottom of the tank.

 

Checked the bottom of the tank and aside from some MG part numbers I found PA6 printed. Does this mean anything to anyone?

 

Jason, can polypropylene be welded?

 

Wassp, you mention a "correct epoxy"...any ideas?

[joe camarda]

Doing a little research and w/ thanks to Mike Stewart and others, I located this site

http://www.urethanesupply.com/identify.php

Also to clarify, the symbol on my tank's bottom is a triangle formed by arrows. Next to it is the printing PA6, which seems to indicate a polyamide, a type of nylon.

 

And beneath this symbol is a small circle with 03 inside of it. Around the diameter there are 12 straight radiating lines (kinda like a clock) and 5 dots between the lines. I'm just guessing that this is some Italian industrial way of noting a production date in the 5th month of 2003 (?).

 

Whoeverthoughtplasticscouldbesodamnconfusing?

[joe camarda]

If (a big "if") anyone is still following this thread, I'm in contact with the urethanesupply.com people to (1) determine what my tank is made of and (2) which of their plastic welding products I should use. Unfortunately it looks like a $250 outlay for the kit I might need

 

Input is still sought and appreciated.