In-Tank Fuel Filter
Instructions for installing the BDSB filter, which is designed to replace the Mahle brand KL 97 filter, normally used inside the gas tank on KTM & Husqvarna bikes.
This is what your fuel pump assembly will look like when done. Except for the clear piece of tube, which will still be the same black stock tube.
Unless you messed it up, like we did, after taking the assembly apart many times. If that happens, we have the right length and diameter clear replacement tubes for you, as you can see.
On the right, you can see our filter disassembled and compared to the KL 97, cut apart.
You can see how large our10 micron filter assembly is, compared to the smaller area and less effective 40 micron filter of the KL 97.
You can see how ours fits together, if you need to take apart. All our O rings are the best Viton material.
So to remove your stock pump assembly from the gas tank, first you remove the tank, turn it upside down and pour all the fuel out. Next, you’ll take the fuel fitting and securing nut off of the bottom of the tank.
More gas may come out then from these holes. The nut is a 17mm size, for the securing nut.
Then you’ll remove the 4 8mm head bolts from the back of the tank, where the wire clip plugged into.
The whole assembly comes out through this hole. Like a fuel pump baby . Hopefully I can turn this into some kind of joke in a future video.
So at this point, you need to get the pump assembly out of the bottom part of the tank. If you have an oversize tank, it will probably just fall out and your good.
If you are taking it out of the stock tank, for the first time, it can be a small pain. Honestly it depends on the tank. Some are tighter than others.
Two things will help you. One is spraying some type of lube, like WD 40 through the gas cap opening, down around the pump assembly.
And two, just using something like the nut driver (shown) to bang on and push the assembly out of it’s tight area. Try not to bugger up the threads when doing this
The whole assembly will just pull out through the hole in the back of the tank now. Now the interesting part starts
Now you have to get the clamp off. Probably the easiest way is to use your side cutters and catch each side of the clamps ears.
Get underneath them and squeeze and the side will come up. Then, as you see on the right, just peel it up
and away.
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At this point, you'll wiggle and pull on the hoses and they will come off the filter. Then you'll put the new clamps on the hoses and install the new filter.
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The side of the filter that says "in" will go towards the pump canister.
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The side of the filter that says '"out" will go towards the part of the assembly that the 4 bolts held to the tank and that the wires clip into.
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When it’s time to squeeze the clamps together, it’s best to use these kind of pliers, which are designed for these clamps if possible. If you don’t have them, then you can use your dykes or side snip pliers.
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You can also use safety wire to secure the connection. We used safety wire on our test filter that ran over 2000 miles. The connection just has to be tight all around the plastic tube. If it isn’t, like if you used a clamp that had a gap in it, the fuel pressure will find a way to leak out of the opening and you’ll see the fuel spray come out when you try to start.
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If it leaks, the bike probably won’t even start
Feed the assembly back through the hole in the tank and then aim the pump assembly into this part of the tank, towards the holes in the bottom.
It helps to spray some type of lube on the plastic case, like WD 40, so that it slides in place easier.
It’s very possible too, that if it’s a tight fit, you’ll have to use some type of long poking device, that you put through the gas cap hole, to push the pump case down to where it needs to be.
With the spigots being close to getting through the holes, it helps to use something like a drill bit, which will fit in one of the holes and then you can guide the assembly into the holes.
Now, which ever one of the threads is closest to the center, go ahead and screw the right fitting onto it so you can pull the whole assembly into place. Then you can get the other part in place. You should be pretty good then.
Fill the tank with enough gas to where it doesn’t cover the new filter. When you try to start, you can now see that the connections leak or don’t leak. If no leaking or spraying of fuel, the bike should start easily. If you see spray, it probably won’t even start. You’ll have to take out and fix.
