TOPIC:

Just looking for every ones opinion. I have purchased a new fuel petcock for the bike which is a vacuum operated one. As you will be aware this wasn't a standard fitment from new. I am now of two minds as to where to take the vacuum take off from. I was going to utilise one of the vacuum outlets used for balancing the carbs which is a quick and easy fix (if I can get a take-off of the appropriate size and thread) or should I drill and tap a new hole in the inlet manifold with a more readily available standard thread for the take-off fitting. Your thoughts please.....

Standard procedure for the XS1100, which was laid out very similar to the KZ1300, was to use one of the ports used for carb syncing. If you still have the nipples attached that ran the emmissions system installed on the US bikes, you're good to go.

I'm with Lucien on this one. Just a thought, what's the vacuum available at wide open throttle? Is it enough to hold the valve open. I just hate running out of gas at 240 kph.

In addition, I wouldn't worry about actually taking it off. If you don't need it anymore, just cap it off (the rubber caps should be available at nearly any hardware store). That was my plan with mine after I removed the emissions system- "thankfully" I had to buy another head, so I just plugged all the vac ports with the provided screws.

Kawboy- I was under the impression that the vacuum rose under acceleration? If you can get the valve to work at idle, full throttle shouldn't be a problem.

I have a '79, found the "proper" brass nipples that screw into the inlets (new old stock), put 3 in, running a vacuum petcock on mine and only using one nipple (closest one), just make sure the line is as short as possible, turned the diaphragm housing around 180 deg so it faced away from the tappet cover, left a bit of length on the vacuum line so I can lift the tank, all is good, runs great.



New petcock

Nipples

Hi kza13, I see you've used silicone tubing for the vacuum takeoff, I used the same stuff for the vacuum takeoff serving the fuel pressure regulator on my ZG1300. It started to discolour as yours is, then eventually it started to 'sweat' & become very sticky on the outside. What is happening is that somehow very small amounts of atomised fuel is finding it's way up inside that vacuum line & as silicone doesn't like petrol it starts to break down. I swapped mine back to rubber. Just thought I'd warn you, even though that silicone pipe is advertised as vacuum piping it doesn't seem to like our bikes