TOPIC:

I have a 79 kz400ltd. I have just discovered that one of the carbs is missing the vacuum cap. (#3 on the picture below).

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how important is this screw? where can i find a replacement for it?

Vacuum caps are usually pretty important. Without them the bike will probably run poorly. Yours is unusual in that it would appear to be a screw rather than a black rubber cap.
I have no idea where you might find a replacement. Is there anything else you could use to plug the hole ?
The vacuum caps on mine are a different style but still homemade in that I use short lenghts of fuel line
and block one end with JB Weld. Whatever you use make sure you can remove it to get access to the hole.

Checking buykawasaki.com, it looks like that IS a "screw,plug" #1 in the carb parts picture. I would take the one off the other carb, go down to my neighborhood friendly hardware store and find one to match it. Get an oring to fit it to make sure it doesn't leak. Most hardware stores have a section with trays full of different hard to find hardware.
What I usually do is find a nut that fits the screw you have to see what thread size it is then find the screw to match. I do that all day long with customers when they bring stuff in like that and hear "gee I never would of thought of that", We have a section like that, from Midwest hardware.
Good luck

Link, click on carb parts.

buykawasaki.com/DefaultFrame.aspx?strCon.../VICHOOSEVEHICLE.ASP

Post edited by: The Milkman, at: 2007/05/12 20:18

That link takes you to the page where you have to enter you bikes info,,, not directly to the carb page.

Post edited by: The Milkman, at: 2007/05/12 20:21

If the vacuum cap is missing, the carb will draw in air and at idle, will race... could actually damage your engine. Most carbs have brass barbs with rubber vacuum caps but yours has the screw with a brass washer. Make sure you use some sort of washer. I honestly don't have any idea what size or thread pitch this fitting is...

I was at the hardware store looking for some other bolts today, and i think i found something that would work. it is a "socket set screw". here is a drawing similar to what i bought?

[img size=150] i have not tried to put this in yet. my only concern is if the head of the old screw worked as a "stop" or if the threads serve as a stop. In other words, since this does not have a head, is there any concern that i may screw it in too far. [img size=135]http://kzrider.com/media/kunena/attachments/legacy/images/socket_set_screw.gif[/img]

sorry. apparently the picture did not post right. let me try again.



my only concern with this setup is whether or not the screw will go in too far, as there will be no head to stop it, or if it will be ok since the threads may only go in so far.

any thoughts?

One more thing to add. The reason that i went with this screw is that i could not find a different bolt that was short enough. the size of the bolt i need is approximately 6mm x6mm and i could not find anything shorter than 12mm that was in a 6mm size.

I just looked at a set of 76 KZ400 carbs here in my office that I just finished rebuilding and they are substantially the same as the 79 as far as the screws that go into the vacuum ports. The missing screw looks like 6mm with 1.0 pitch... It is a brass screw (or maybe bronze?). Take note that the head of the screw has a very flat surface with an aluminum compression washer to seal it. I would try and find a 6mm pan head screw (flat blade screw driver needed to install) and fine a small brass or aluminum washer to seal the fitting. The pan screw will have a flat surface facing the carb body... If you use the allen bolt, put a wrap of telfon tape on the thread to seal it...

Check your PM.