“This fuel filter is designed to fit into the 3/4 opening of your fuel tank. It helps prevent dirt and debris from entering in your fuel system. This filter will help prolong the life of the rest of the fuel system and is highly recommended for EFI bikes.”
Since the introduction of Husaberg and KTM fuel injected bikes, it has been the accepted wisdom that adding the in-tank filter sock was a good idea. It would be a first step to guard against dirt infiltration into the EFI system. Dirt will ultimately lead to a clogged injector and that is a problem.
Of course the sock is only one of the filters in the system. There is one in the fuel pump itself inside the tank. In 2012 KTM decided to add a second filter to the fuel line. In 2013 this in-line filter was moved to have easy access at the quick disconnect coupler. I have always suggested adding the sock for those who ride in Baja where the gas has a reputation for being dirty.
When I installed the 13 litre tank on the 2013 350exc last year I decided to go ahead and add the sock. It fits right into the filler neck on the OEM and KTM Hard Equipment tanks. The fuel cap holds it in place and it stays very secure that way. When fueling the bike, the sock slows down the flow just a bit. It requires a careful hand on the pump to make sure it does not splash fuel around. But once you learn the technique, it is not a real bother. The sock does not fit properly in the aftermarket Acerbis tank.
The sock has now been in place on the 350 for at least 60 hours. I decided it was time to take it out for an inspection. It must be full of all kinds of stuff. How often have you looked down into the clear tank of a bike to see all manner of debris sitting at the bottom? I have not been particular about the fuel I run either. I buy the cheapest gas, use Pemex Magna and even get fuel from gallon jugs along the highway in Mexico.
I pulled the filter out and let it air dry overnight. The next day I carefully put down a clean white paper towel and proceeded to turn the filter inside out. That would give me a good view of the contents. Guess what I found? Absolutely nothing, nada, zip! Other than some slight discoloration, it is as clean as the day I put it in.
I am baffled. How can this possibly be? There is no way that all the fuel I used was this clean. I am still stumped. There must be some logic here that I am overlooking. Has everything rattled around enough to disintegrate into particles small enough to pass through the mesh? I don’t know the exact mesh size, but it must be similar the 20 micron in-line filter.
So there you go. I don’t have an answer to the situation or a recommendation as to the effectiveness of the filter. It certainly isn’t doing any harm, but is there any benefit to it? If you have any insight on this, please share it with us.