To do or not to do?

General Composites Discussions Composites Talk
#1

I received a call from a potential customer this morning. He has a stock KTM gas tank with the internal resin flaking off. This tank has a history. He purchased the bike new and the first tank began to leak after a couple of weeks. KTM replaced it with this one but it began to leak as well. He sent it in and after 8 months it came back with a new internal coating. Apparently, they use an incompatible resin system, which is being broken down by gasoline. The OEM that produced the tank went out of business and so he is stuck with the potion of replacing with a different tank, which is smaller. He wants to keep this one and asked me if it is repairable.

Has anyone here tried a repair like this before? If yes how did you do it? It’s going to be impossible to remove the old resin without cutting the tank open so my first thought would be to split the tank, sand out the old coating, reassemble it and re-coat it. I don’t see any reason why that wouldn’t work but maybe someone here has a better idea.

Likely the safest option would be to make new tank using the old a plug.

#2

Check out the POR 15 fuel system coating - also, take a look at their Marine Clean. It’s not phosphoric acid (naval jelly) and their products are fiberglass safe and styrene free.

http://www.por15.com/Fuel-System-Restoration/products/12/

#3

Sandblasting could be an option, fine grit or walnut shells (oldtimer car restoration shops use this blast media), it is on the inside anyway. May be then you hit two birds with one stone, the grit leaves a good surface preperation for a coating. In Germany Timeout sells some epoxy resin compatible with fuels.
Second idea, go to a company with a big tumbler, vibration machine. In German called " Gleitschleifen oder Trowalisieren", they have tons of different ceramic or other materials for grinding/ polishing. Wrap the tank in some bubble wrap or anything to protect the surface. Fill the tank with the tumbling media, let the machine do the job.

#4

regarding the por15, ive seen some hit or miss stories on the product actually working.
i think one of the deciding factors is what type of fuel will he be using. seems from my reading that ethanol based fuels, as well as high octane race gas will eventually eat most resin systems out there.

#5

Thanks for the help. I’ve looked at the POR15 stuff but the instructions say it is only suitable for steel tanks.

I’ve never thought of tumble polishing the inside. That is a great idea.

Now I just need to find a resin system that can handle ethanol based fuel.

#6

check out this thread:

http://www.compositescentral.com/showthread.php?t=7588

i’m going to try the 3M polysulfide material when i take a stab at a tank. it seems like a product that was made just for the harsh environment, and since its used in the aerospace industry i’m guessing its pretty well proven.
only thoughts i had on it being a problem were applying it and possible weight issues.

#7

I recently redid the inside of the tank on my motorcycle and this is what I used. It worked great and was easy.
It’s called Kreem Kreem I found it here. I however bought it at my local Harley davidson dealer.
https://www.denniskirk.com/3152.sku?utm_source=google&utm_medium=cse&gclid=CIbm3dKLhrQCFQLxOgodphYA3g