Help with general carb stuff for '80 kz750 ltd-4

Ok so I am just getting into this and already having issues. I am out of my element when it comes to carbs. I have lots of questions so bare with me.

So finally after lots of grunting and sweat I got the carbs off the bike. They are currently in my kitchen. LOL. The carb kits have been ordered and will be in Wednesday.

So when I bough this bike from the guy he told me that the exhaust baffles had been removed and the carbs may need to be re-jetted. The bike did run before I pulled it apart but it had trouble with idle and would stall out unless I opened up the throttle. The previous owner told me that the carbs did need to be cleaned and the bike has been sitting for 2 years. If I do need to replace the jets (if i screw them up while cleaning them), do I need a different size since the baffles have been removed?

Ok, so the guy told me that he removed one of the fuel hoses and now the bike would only run with the petcock on "PRI." Nothing is connected to the "ON" side of the petcock. there is a hose that looks it goes into the second carb into a vacuum hole. Is this hose suppose to go to the "ON" side of the petcock. If not, where is the hose that goes to that "ON" spot?

Alright. I got the float bowls off and cleaned them up. I tried to remove the pilot jet on the first carb I was working on and it may have stripped out. Not the threads it screws into but the top where the flat head goes. I know that the jets are soft and can deform easily but this thing would not budge. Any idea on how to get this jet out since it is stuck?

The caps on the top 2 outside carbs have rusted screws and they won't budge either. I am afraid to round them out if I put anymore force on them. Has anyone come across this and had a better way of dealing with it? Am i gonna have to tap the screws out of the caps?

Ugh, I feel dumb right now. I had someone offer to rebuild this for me but I said no because my theory was this was gonna be my bike and I need to know how to work with the carbs and adjust them to what I want/need. Now I am having issues. If any of my descriptions are not technically correct I can get some pics up to assist in my amateur descriptions. Any help would be so much appreciated. Thanks guys. Safe riding.

Hi there,

Dont sweat it, you can do it.

If the bike was sitting for a few years then they could probably do with a good cleaning to get rid of the gum left when gas evaporated. The best way to do this is to take then completely apart. Get 4 little bowls labelled 1 - 4 and put pieces from carb 1 in bowl 1 etc. Soaking the bodies in carb cleaner and run nylon bristle or fine wire through every passage you can find. Finally blow everything out with compressed air. I use the airline at the local gas station.

You may not need to rejet for the missing baffle. You will only be able to tell once you get the bike running again. If you do need to rejet it will not be a major job and the jets are only about $2 each from Z1Enterprises.

You have problems taking the carbs apart. When you open them up you should see something like in the picture below - I think your carbs are very similar to mine - assuming they are stock. In the pic at 12 and 6 there are the primary main and secondary main brass jets. At 3 there is a plastic plug and the pilot jet is underneath. The pilot jet is easy to gum up. If the head of one of the brass jets at 12 or 6 is mushed up then I would suggest using something like a Grabit screw extractor www.aldn.com/grabit/ after first soaking over night with PB Blaster. Worked for me. The same tool and PB Blaster might come in handy for the rusted and stuck screws on top. If you dont have a manual try to get one. For parts diagrams go to kawasaki.com -> owner info -> parts diagrams etc. You might have to select 1982 for the year.

The petcocks are usually vacuum activated and the narrow vacuum hose from the nipple on the #2 carb should connect to the corresponding nipple on the petcock. Sometimes an owner will have problems with the petcock and just use Prime but you have to remember to switch to Pri before running and switch off when stopped. Also, if the bike is only running on Prime and the vacuum line disconnected then the vacuum nipple on the carb should be capped with a rubber cap or the vacuum line plugged with a bolt or something.

Hopefully this will help get you started and others much more knowledgeable than I will be along soon with more.

It will be worth it in the end and like you say you will have a much better understanding of how it works.
Good Luck.

Ok so I got the cap screws off. Destroyed 2 in the process but they are off. Kits should have the jets in them that I mushed up. It's the "12 O'clock" one (primary main jet, I believe) on the pic. (Thanks for that by the way). I will either have to pull it out with pliers or get the ez-out set. Got a mechanic from work that has a set and he is willing to let me borrow them. Everything else is coming along. Goal is to have this bike running by June 1 so I can ride it to my new apartment. Decided i am just gonna cap off the vacuum hose from the petcock and use it in the "PRI" position until I can fuss with it later. Hope that won't cause any damage. I know I have to shut it off if I use it that way so it doesn't leak fuel. I do have a manual for the bike by Clymer. It is helpful until you run into a major issue. Thanks for the help. Will update later.

greasechick557 wrote:

...Ok, so the guy told me that he removed one of the fuel hoses and now the bike would only run with the petcock on "PRI." Nothing is connected to the "ON" side of the petcock. there is a hose that looks it goes into the second carb into a vacuum hole. Is this hose suppose to go to the "ON" side of the petcock. If not, where is the hose that goes to that "ON" spot?....

The guy probably removed the smaller vacuum hose from the petcock vacuum nipple, which would prevent fuel flow except on PRI. This vacuum hose is supposed to connect the petcock vacuum nipple to a vacuum nipple on the carbs.

The other (larger) petcock nipple is for the fuel line.

Petcock positions ON and RES (reserve) require vacuum to flow fuel. Designed to prevent fuel flow when the engine isn't running.


Petcock position PRI (prime) flows fuel regardless of vacuum.

Good Fortune!

With pliers or EZ out just go easy. The brass is pretty soft. Before you dig into them though can you see what numbers are stamped on them ..or on one of the good condition ones ? You might need a magnifying glass. This will tell yu what you need to order www.z1enterprises.com/SearchResult.aspx?...True&KeyWords=keihin
Z1 Enterprises dont list the smaller one but I have gotten them here in to past. You just need to call or email.
Good luck

Ok so I got the screws out of the cap. I will have to replace 2 of the screws but the carb bodies are fine. As far as the jet that is mushed up...I can't see the number on it. I'll have to check the good ones. The manual lists stock numbers and it's suppose to be stock.

I know that the PRI position on the petcock does not require the ecgine suction. I am just wondering if I run it on "PRI", as long as I remember to shut it off when I turn the bike off, will there be any permanent damage?

Orders come in tomorrow. Can't wait to get back to work on it. I'll let you guys know what happens.

greasechick557 wrote:

...wondering if I run it on "PRI", as long as I remember to shut it off when I turn the bike off, will there be any permanent damage?....

Nope, won't hurt the bike.
But without a reserve, more likely to "run out of gas."
Late at night, of course, and at least 15 miles from an open pump. :pinch:

Good Fortune!

Petcocks get crud and grit inside, and sometimes can be rejuvenated by disassembly, cleaning, and reassembling.

Pay particular attention to the diaphram, spring, o-ring, and selector gasket.

If needed, petcock rebuild kits are likely available at Z1E.

A parts diagram is available at kawasaki.com under "Fuel Tank."

Good Fortune!

[Click on image to enhance view.]

Links to Z1E listings:

www.z1enterprises.com/detail.aspx?ID=305

www.z1enterprises.com/detail.aspx?ID=307

Thanks for all the helpful replies. I am leaving the petcock be for now. Will probably end up getting the rebuild kit for it. Z1 helped me with the carb jets. Carb is all set and back in the bike. Bike runs much better. Still may need some adjusting. My next project is the seat. Thanks for the help with the carbs. I will have to post some pics when I finish everything.

greasechick557 wrote:

...am leaving the petcock be for now. Will probably end up getting the rebuild kit for it....

Meanwhile . . . :pinch:

[Click on image to hear "Damnit! My memory's awful!"]