A rebuild of this unit is probably just a waste of time. I've read where a number of people said that if you spend a little time cleaning the surfaces these kits will work, but I will go on the record saying "Screw That". It's not worth the chance of getting gas in your crankcase. IMHO, just buy a pingel adapter plate and a standard on/off/res petcock and be done with it. (Just remember to turn your fuel off when you turn off the bike).

So, if you still want to try to rebuild the vacuum fuel valve and save $20, then continue on to step #2.

1. Lift seat & remove the metal plate and bolt that secures the back of the tank.

2. Disconnect the electrical connector coming from the bottom of the gas tank. It connects to the fuel gauge assembly.

3. Clamp the fuel line to prevent spilling and pull off the carb side of the fuel line if you can get to it. If you plan to replace the fuel line anyway, just cut it.

4. Drain fuel into a suitable container...like the neighbors yard.

1. There are two 6mm phillips head screws placed 34mm apart on the petcock. Remove those.

2. Gently lift the petcock off of the gas tank and be sure to grab the fuel filter as soon as you can so that it doesn't fall into the tank. (If it does you need to remove the fuel gauge and fish the filter out from that hole.)

1. Now, remove the two small phillips screws that hold the cover on the switch.

2. Directly under this plate is a wave washer, don't lose it, you must re-use it.

3. Pull the switch assembly out. There is supposed to be an o-ring around the circumference of this part. It will probably be all mangled. (Mine was split into three).

4. Below this is a plastic plate with 4 holes in it. You will be replacing this too. 

This part is pretty easy, but if it is going to work you must be careful to clean up all the surfaces inside the valve. Otherwise, this whole exercise will be for nothing.  

Take some very fine sandpaper, like 800 grit or more and polish the surfaces. Then install all the new plate and o-rings with generous use of silicone grease. 

Now that you have the valve repaired you need to fix the diaphragm on the back side of the valve. The problem with these parts are that the replacements aren't exactly like the stock parts. For example, the stock parts have beveled seals and the replacements use a round o-ring. This creates the potential for the post to not seat correctly and let the gasoline have it's way with you.

This part is kind of tricky because you must pull the old diaphragm out and put the new one in EXACTLY in the orientation of the old one. Note, there is a small channel which must be replaced facing the inside of the valve.

There are two layers to the diaphragm. One goes on each side of the plastic block. Just bunch up the corners of the one you want to push through and there ya go.

Then just bolt it all back together. 

Finally, you will need to replace the big o-ring that seals the valve to the tank. It's the most simple part of this project.

Just pop out the old one  and install the new one with some silicone grease and VIOLA!! you now have a rebuilt (but probably still leaking) petcock.