vac leaks

ok got the head jb welded ( another thread entirely) boots put back on and sealed ( no leaks) still the idle isnt the same setting on the idle stop screw every time, constantly adjusting it before riding. also when stopped if i disengage the clutch the idle perks up and then if i just let out a little on the clutch then itll drop? any suggestions? is there a way to check the diaphrams individually? had it all apart cleaned blew out and rebuilt. all diaphrams seemed good no visable holes. slides actuated well. :S

i see some 28s in classified section;)

Has ignition timing advancer unit been checked to assure free easy operation and springs in good condition? Might consider removing for cleaning, inspection and lubricating.

Am thinking advancer might not be readily returning to completely closed position at idle speed.

While points cover is off, would double check timing with strobe light. If still using points, clean, check and adjust gap before using strobe light.

If above is no help, would then also perform compression check and assure proper valve clearances.

Good luck!

checking valves is one thing i havent done yet, been putting it off cuz im a newbie. but shes not a runnin so i may as well get er donw at least ill know what i got.

"Checking" is the easy part just using a feeler gauge between cam and shim with cam pointed away from shim.
The "adjustment" via changing shim is more involved.
Should check with cold engine ("sitting overnight" cold).

Would also check compression. If compression is good on a cold engine, but a valve is tight (lacks sufficient clearance), remember that gap clearance decreases further as the engine warms so as to leave zero clearance with valve not completely closing and results in valve leaking and causing loss of compression.

Don't forget about the advancer unit, points gaps and timing (which I would do first).

Good luck.

The 78 KZ1000 came with VM carburetors that don't have diaphragms. What kind of carburetors are we talking about in this thread?

bs34

The air jets and passageways from air jets to main jet and/pilot jet wells needs to be cleaned properly. Some of the 34s have the pilot jets picking up gas from the main jet well and some pick it up directly from the bowl. The ones that pull gas from the main jet well are plugged, and if the plugs are missing and should be there, the bike won't idle well...

Your explanation of the symptoms wasn't as clear as it could be for me... if the idle is erratic; that is, it is stable then zooms up to drop back down; well the choke plunger pads may be leaking. You could try and jiggle the choke rod just a tad when the idle is fluctuating and if the idle comes down right away (at least temporarily), the poor idle may be the plunger pads are shot and need to be replaced.

you could also have a tight throttle cable, air leaks in a variety of different places. Also, check your float levels (wet).

WiredGeorge,

I'm trying to connect the dots between this thread and my problem with rpm's getting stuck when above 3K rpm, and it struck me that your comment about worn or shot choke plunger pads might cause the idle problem.

Here's another observation I have made on my bike: the choke doesn't seem to react or do much when engaged, or than make it even harder to start. Is it possible that my "out-of-control" rpm problem could be caused by leaky choke plunger pads, as much as causing the choke to not be very effective? In other words, my vac leak (sucking air) is actually happening through the choke plunger pads?

I'm assuming the choke plunger pads are the bellow-shaped rubber caps called "starter plunger cap", part number 16012-1010, listed on parts diagram on Kawasaki.com?

Post edited by: Norseman, at: 2007/05/31 00:27

Nope... the caps you speak up seal the plungers from the outside and must be in good shape but the pads themselves seat down inside the carburetor on the end of the plunger and are an integral part of the plunger itself. I replace the pads, if needed, during rebuilds otherwise, there is an air leak which causes the idle to shoot up especially when sitting at a light. The pilot air jet ALWAYS feeds air into the choke plunger well and if the seal is broken, the air gets through and leans the overall air/fuel mixture. Old plungers can have deep indentation or the pads can be very hard and the seal can be poor. You can check your pads by removing the plungers (split carb rack) and pulling them and observing the rubber... if deeply indented, they most likely will leak and you can poke them with a dental probe and if the rubber is hardened (even though not deeply indented), they can leak.

You may also have another problem in that the gas pickups for the choke circuit may also be clogged and need to be cleaned if the choke doesn't have much effect when actuated. The choke on a BS34 is sort of all on or all off... you can set the choke up in a "mid" position as there is a single indent on the choke rod but once they are open, they are open (enrichment circuit actually as opposed to a true choke).

WiredGeorge,

I'm confused - I just completely disassembled my BS34's for cleaning, and there were no pads on the choke plunger or stuck inside the carbs. I checked Kawasaki.com parts diagram for my 1981 KZ1000M1 CSR, and it does not display or list such a component.

Is this something you have designed, or is it factory equipment? Appreciate any guidance here.

The choke plunger is a rod with a barrel type section inside the carb body. On the end of the barrel section is a rubber pad. There is a 1/2" long "needle" that goes into the seat in the middle of the pad. The pads don't show on any parts diagram.