1981 KZ650H Carburetor Question

I am having troubles with my bike not running. It will idle right now but it will not transition into throttle at all. I am completely lost with this carburetor crap, so be ready for questions galore.
First: On the bottom of the number 2 carb, there is a Triangle mount (part of acc. pump?) that has nothing there, no cap, diaphragm, nothing.I have heard somewhere that the '81 CSR did not come with this feature? Can someone chime in?
Second: I have had the carbs. rebuilt by my father-in-law who has rebuild many many snowmobile carbs, so I am confident that they are rebuilt well. My main question is what the heck can cause the bike to idle okay, it needs a touch of choke (barely any) to idle well, but it refuses to even think about transitioning to throttle.

ANY help at all would be great! I finally have a garage so I can really dive into it now.

Howdy. I have the same bike. The triangular vacuum sensor on our bikes is disabled, so the tri-cover isn't needed.

The #2 carb has an accelerator pump: twisting the throttle squirts fuel into the carb bore via the nozzles that project into the opening of each carb. You can check its function by actuating the throttle pulley vigorously: fuel should squirt straight back without hitting the sides.

You should have to use the choke to start the bike & the amount of choke is dependent upon the temperature. The colder it is, the more choke that is needed. The owner's manual has some guidelines in the Starting the Engine section. If the bike is cold & starts without the choke, then it kinda sounds like maybe the throttle slide gap is too great.
(FYI: the bike doesn't really have a choke - it's a starter circuit which allows the uptake of more fuel).

Troubleshooting isn't my forte, so I just check and set everything as per the factory manual, then try to figure out what's wrong. So you should verify how stuff is set: fuel level, throttle slide gap, carburetor synchronization, accelerator pump functionality. You'll have to figure out the air screw setting: there isn't a factory spec for that. ~2 turns out would be a starting point.

Is the airbox & filter installed? Stock exhaust?

PS: I have a factory manual for sale in the classifieds here.

ShouterVW wrote:

... will idle...will not transition into throttle at all...what the heck can cause the bike to idle okay, it needs a touch of choke (barely any) to idle well, but it refuses to even think about transitioning to throttle....

In an earlier related thread, ShouterVW wrote:

...this past summer I picked up a 1981 CSR650...did not run well, flooding out of number 2 carb...had the carburetors rebuilt, that got the bike idling ok, but instantly dieing under throttle....

Perhaps pilot circuit is too lean.

Could experiment with different settings of air screws, starting much richer at say 1/2 turn out counter-clockwise from lightly seated.

Does richer air screw setting make any noticeable effect, or does the engine still die when cracking the throttle?

Fuel level inside the float bowls may be too low, causing too lean mixture.
Have levels been checked using the clear tube method?

Good Fortune!

Once I get around to buying more kerosene for the garage heater I am going to dive right into it. I have heard of checking the float levels using the clear tube method, but am unsure on the procedure involved in the method. Can anyone send a link or explain how this works? Thanks. I posted pictures in my "new member" thread if you guys wanna take a look.

ShouterVW wrote:

...have heard of checking the float levels using the clear tube method, but am unsure on the procedure involved in the method. Can anyone send a link or explain how this works?...

[Click on image to enlarge view.]



3 mm is ideal.
Best to set all carbs at the same level.

All of this and so much more is covered and well-explained in the official Kawasaki Service Manual, which is superior to after-market manuals.

Good Fortune!

JMKZHI wrote:

...I have a factory manual for sale in the classifieds here.[/i]

This manual is imo reasonably priced.

It's listed under "Motorcycle Parts."

It's not listed under Manuals.

Good Fortune!

ShouterVW wrote:

Once I get around to buying more kerosene for the garage heater I am going to dive right into it. I have heard of checking the float levels using the clear tube method, but am unsure on the procedure involved in the method. Can anyone send a link or explain how this works? Thanks. I posted pictures in my "new member" thread if you guys wanna take a look.

On the 81 650-CSR checking the fuel level is easy (Service Fuel Level Check). Simply attach clear tubing to the nipple on the bottom of the carb, hold it up high against the carb body, then open the drain screw. Fuel should flow into the tubing. Continue holding the tubing up high & note the level of the fuel in relation to the lowest point of the carb body. Then lower the tubing a little to see if the fuel returns to that level. If you lower the tubing then raise it, start over. Factory spec is 3mm +/- 1mm below the carb body.

Note: the #2 carb has two ports - one is for the overflow, while the other one is for doing the Service Fuel Level Check. On the other carbs each nipple on them serves both purposes.

Edit: you don't need the special tool to do the Service Fuel Level Check.