Topic: petcock for Cb750 gas tank?

[cb750photog]

Well I picked up my 73 CB750 for really cheap it was missing the fuel tank so I ordered one for it off eBay.  It didn't have the petcock on it witch I knew at the time. And so I ordered one for it. The tank was supposed to be off a 73 but it isn't the thread size is a lot bigger than the petcock I ordered and it is also on the wrong side for a 73. So I guess my question is does anyone know what size it might be? I measured it with my calipers and got just shy of 20mm. But wasn't sure on threads what I was supposed to be measuring.

[754]

Its likely a 75 or 76 tank..

[whitjonw]

The tank was supposed to be off a 73 but it isn't the thread size is a lot bigger than the petcock I ordered and it is also on the wrong side for a 73.

Your petcock is of course supposed to be on the right side of the bike. It is fixed to the tank with 2 screws which are internally fitted through the petcock.

It should look like this:



Screws:




No doubt, you have the wrong tank for a '73. Post a pic or two so we can see what you have for sure.

[cb750photog]

Here is a picture of it on the bike. The petcock on this tank is on the left side and it threads on not screw on like that on a 73.w I'll get more picture of the tank underside tomorrow if needed it's dark out now.

[754]

It is the late tank, threads are same as 400 4, i took the petcock off my 75 750 tank and put it on a 400 4 tank. Your threads should look like the pic i posted below.
 It will be harder to get at your idle adjustment.
 Your aircleaner is called a breadbox, same as mine..aftermarket.

[mrbreeze]

I don't see a bung on that white tank. You can see a bung on Frank's (754) picture. The left side bung is on a 75-76K tank. The 74 & earlier is the right side with the 2 screws to mount to the tank. Either tank will work on 69 to 76 K's but you have to move fuel lines around and like Frank said....it's harder to get to idle adjuster with left side petcock.

[cb750photog]

Yeah it has the bung just like the one in the picture is I will order a 20mm 1.5 thread petcock. Is it better to have the nipple on the side or out the bottom?

[754]

Out the bottom , your tank looked like this before paint..