Installing a Bulkhead Fitting on an FJR1300

Here's a photo of the tools and supplies I used. The photos were digital shots I took at FJRGoodies.com's shop (but can now be found here on this Website) which I printed to use as disassembly/reassembly guides.

I had already removed the gas tank, the procedure for which is also documented here at this Website with photos.

My first problem was draining out the remaining gas from the tank. As the built-in vacuum petcock won't let the fuel drain out the outlet nozzle, I had to use a length of fuel line to siphon out the remaining fuel. Damn, I hate the taste of pump gas! :-)

SHOP TIP: To drain tanks that have a vacuum operated petcock, get a large syringe from the drug store. Attach a suitable section of vacuum line to the fitting on the tank. Pull a vacuum with the syringe, and lock the plunger in place with a pair of Vice Grips. Liquid will now flow from the out put line.

With the gas tank sitting upside down, the next step was to remove the fuel gauge sending unit and petcock assembly. As always, it pays to make a drawing for yourself indicating what it looked like before you took it apart. Do this, it's worth the effort, even though you have the advantage of using this Web page too. Trust me.

Remove the (6) 3mm Allen bolts, and the aluminum retaining ring.

Getting the fuel gauge sending unit out is tough. You have to wiggle and push and wiggle some more, and when you've done just the right combination, out it comes. Set it carefully aside. It may have some residual fuel in it, so be careful.

With the fuel gauge sending unit removed, I taped the razor-sharp edges of the hole with duct tape, and used a clean, old cotton towel to soak up the remaining fuel from inside the tank. I propped up the tank on its side, with the fuel filler cap open, and let it air dry for 24 hrs, then ran a compressor hose into it for another 5 minutes to evacuate all residual gas fumes.

Note the small US Quarter sized depression in the bottom of the gas tank identified by the red arrow in the photo above. It is conveniently not covered by the silver insulation. That's where I installed my bulkhead fitting.

Here's the bulkhead fitting I used. I found it at the House of Hose, a large industrial hose and fitting supply place in Spokane, WA. Various designs and arrangements will work, but given the small amount of room under the FJR's gas tank, you don't want much more height than this one offers.

It consists of a steel piece with a solid end, threaded for a 90 degree hose fitting, and threaded on the other end. It takes a 3/4" hole. I got mine with two Viton O-rings (gasoline resistant).

SHOP TIP: When using an O-ring -- backing it up with a washer between the O-ring and the nut or shoulder gives less of a chance for the O-ring to twist and distort. The washer spreads the force over the whole area of the O-ring and applies an even squeeze type of pressure.

I drilled the retaining nut, and put a hole through the bulkhead fitting inline with the hose fitting, so that I could safety wire it in place, once installed. I practiced making the hole in this scrap of aluminum, which is approximately the same thickness as the steel bottom of the gas tank. By using this I could also get the holes drilled properly so they'd line up when the fitting was tightened down.

To drill the hole in the gas tank, I used a 3/4" Uni-bit, as shown in the photo above. THIS IS THE TYPE OF BIT YOU NEED TO DRILL THE GAS TANK! I do not advise using anything else -- you'll surely ruin your gas tank if you try to do it with a conventional bit.

Practice with a test hole in a scrap of metal at least once, to insure the hole that counts gets done right. In my case, I lucked out because the maximum diameter of my Uni-bit is exactly the diameter of the hole needed for the bulkhead fitting.

SHOP TIP: When drilling a tank using the Uni-bit -- once the desired hole size has been reached, continue very slowly so the next step on the bit puts a small chamfer on the hole. (Don't go too far!) This will allow the O-ring to have some what of a seat to form in to.

Before drilling I took the plastic end off a container and carefully duct taped it to the inside of the gas tank, directly under the place where I drilled the hole. This, obviously, is to catch the metal chips from the drilling operation. They could be a bitch to get out of the tank, otherwise.

I next carefully punched a dimple in the exact center of the quarter-sized depression where I wanted the hole. Then I drilled a small starter hole, then a slightly larger one, then finally a 1/4" hole. For that, I used conventional bits.

Then I use the Uni-bit to cut a single perfectly round and neat 3/4" hole.

Here's all the metal chips the would have ended up inside the tank if I hadn't used this cup. There were even more chips outside the tank, but they were easy to brush off.

After removing the catch-cup, I carefully felt around inside the tank but couldn't feel any loose metal chips. Being extra cautious, I used a clean, lightly-oiled rag and wiped the inside bottom (really the underside of the top) of the tank, but didn't come out with any metal. Success!

SHOP TIP: To remove steel chips from the tank after drilling, use a magnet on a wand. Then follow with an oiled rag wipe.

There isn't much room to work with inside the tank. In fact, if you have very large hands you may need an assistant with small hands for tightening the bulkhead fitting in place.

I used a Snap-On "stubby" ratchet, with a 1.125" SAE socket and a 3/8ths drive adapter. I'd already verified that this would work, and that I could both get it inside the tank, and had room inside to use it.

After a liberal application of Permatex "Motorcycle" Form-a-Gasket, I tightened the fitting in place. [Aviation-grade Permatex (3d) will also work well, both are gasoline proof, but the motorcycle grade has a wider temp. range (up to 400 degrees F.)].

I tried to safety wire it from inside the tank, but no joy. I ended up threading the safety wire in from the gas filler hole, through the fitting, and back out. Then I twisted it from outside the tank. Took a zillion twists, but eventually I could feel inside the tank that it was snug. I reached in and clipped it off, leaving a small tail.

Note: It may be overkill to safety wire the fitting -- I was just being extra cautious.

Here's how it came out. I had to trim just a tiny bit of the insulation away to clear the fitting.

A view of the bottom of the tank, showing the angle you want for the hose attachment -- namely, pointing at the vent hoses. Note the duct tape still in place which kept my hands and wrists from being shredded.

Be sure to wipe off the residual glue with Goo-Gone after you remove the tape. That surface needs to be completely clean for the fuel gauge assembly to seat properly and without leaking.

Here's a view of the bulkhead fitting with the fuel line attached, just before the gas tank was bolted back down.

Actually, I installed the rear pivot bolt, and left the top two bolts out until after I'd poured in about 3 gallons of fuel to make sure everything was solid and not leaking. I let it sit for a few hours, then rolled the bike out into the driveway (just in case!) and started it up. Let it run for a minute then shut it off and checked again. Still leak free!

The fuzzy photo above shows how I routed the aux tank's fuel line down the side rail. It's easy to see how to route it without needing to cut or drill anything, so I didn't take any more photos of that.

In this photo you can see the BMW-style dry-break hose connector (the white thing pointed to by the red arrow) that allows the aux tank to be easily, quickly and safely removed.

My FJRGoodies.com Top Gun aux fuel cell. The red handle is the fuel "ON" switch, easily reached from the saddle. Takes the FJR's total fuel capacity up to 11.3 gallons. It's gravity feed, no aux fuel pump or wiring to mess with. It doesn't interfere with my Rich's Custom seat either.

I plan to enclose the mounts underneath to create an out-of-visible-sight storage area for tools, flares, first aid kit, etc.