Topic: '78 550K: Fuel tank/tank filter/petcock questions

[Scott S]

 So, I thought the non-rebuildable factory petcock on my '78 550K was plugged up on the reserve side. I ordered and aftermarket filter and, while it fits, the outlet is different than stock and it's a little larger, physically.

 As I was looking at the old petcock, I noticed that I couldn't see a hole for the reserve side ANYWHERE. So, I pulled out the old, hard rubber grommet and ...whatta ya know! There is a reserve side and it works fine. The grommet had gotten flattened and plugged up the reserve side. Pulled the new grommet from the aftermarket petcock and DONE!

 Now, I want to clean the inside of the tank using The Works method and I'm having a hard time getting the last bit of fuel out. That worried me a little because if I can't get it empty now, I sure don't want to leave cleaner, rinse water, etc, inside.
 I shine a flashlight in and I see the in tank filter. That's what's holding the last little bit of gas from coming out. The filter seems to be in fine shape, but...HOW DO I REMOVE IT?

 I don't see anything at the petcock bung to grab onto. I don't want to push it into the tank for fear that I won't be able to get it out of the gas cap hole. What am I missing here?

[Scott S]

 Here are some crappy pics of the petcock and old grommet. (Sorry, my camera take crap close-ups).
 The crescent shaped area is the opening for the reserve side. The old grommet was plugging up that area.
  What about the pick up tube? It's just plastic....is that stock or has someone replaced it?



I couldn't get a good pic of the fuel bung. The main reason I'm even bothering to remove the in tank filter is that I'm concerned about The Works toilet bowl cleaner damaging it. The main ingredient in The Works is (I believe) phosphoric acid. Will that damage the mesh of the filter? It's plastic, right?

[TommyT]

That looks 100% identical to the petcock on my Cb750K.  Plastic tube and all.  Even the 77 Cb750K tank I have has same plastic tube and petcock, that one the outlet is off the side not the back.

I got a new o ring and installed on mine and it has been working fine, I have also seen a copper washer being used in there with success

[Scott S]

 Yes, it was definitely the old rubber washer that was causing the problem. I used the rubber washer from the aftermarket petcock and I can blow through both the reserve and "normal" sides of the petcock.

 Now...what to do about the filter? I did just talk to the local Honda shop and it's available. But do I push the old one into the tank? Grab it with a pick and pull it out (thus, destroying it in the proccess)?

[Cheffish]

I pried mine out. And it got ruined. But on a tank that old, I'd replace it anyway.

[Scott S]

 Yep...pried it out and ruined it. But that's OK. It was filthy and had a small tear in it anyway. Ordered one from Honda about two minutes ago.

 BTW, one more tank clean as a whistle using "The Works" toilet bowl cleaner method!