TOPIC:

So I have a 78 kz1000 a2 I have been restoring for the past few months and for the most part every problem I have ran into has had a solution on this forum, until now. So after all proper maintenance per the kawasaki service manual I am now at syncing the carbs, but I am at a wall! So at idle, when I twist the throttle to rev it up, the RPMs stay there for at least 45 seconds (about 3k RPM) My first thought was the cables, but I have checked their tightness and have now even watched the pulley return to "closed" So I decided to re-clean the carbs (vm26s with no accelerator pump and a vacuum nipple on #3) but it is still giving me the same problem. Vacuum nipple is plugged. Any thoughts or experience with this issue?

Three of the most common causes are--

1- Air leaks, particularly the intake manifolds (boots). If they are hard, have surface cracks or the carbs are not fully seated, additional air is introduced causing the mixture to go crazy lean.

2- Frayed, dirty, dry (not properly lubricated) or improperly adjusted throttle cables. You seem to have eliminated this, but it would not hurt to double check.

3- Sticking ignition advancer. Carefully clean and lubricate and insure smooth operation.

Classic vacuum leak.

Check your carb boots (official name; Carburetor Holder) to make sure they are tight to the head and the carbs. I like using type 2 sealant on the boots at the heads others don't. If everything is tight and such you can pray carb cleaner around the boots while the engine is running, if the revs dip or the engine dies you know where the leak is.

Otherwise something is out of adjustment or you have jetting issues.

You should check the carb holders for leaks. They will eventually develop tiny cracks in the mating surfaces between the holders and the cylinder head that can cause them to leak. These cracks cannot be seen with the carb holders in place. I suggest you try the following. Get the engine warmed up and temporarily set the idle as low as possible without killing the engine (lower than 900 rpm if possible). The lower the better because with the idle very low the slides are nearly shut and the vacuum inside the carb holders is at its highest. Then spray carb cleaner around the carb holders, especially where they mate with the cylinder head and where the carbs attach to them. Carb cleaner works best for this test as it doesn't leave an oily mess with WD40 or evaporate so quickly that it is not drawn into the leaks as can happen with propane or starting fluid (ether). If the engine dies or reacts to the carb cleaner, you need to replace the carb holders. Carb holder leak related problems are noticeable at idle but generally don't have much impact when riding because the throttle is open. If you find you need to replace the carb holders soak the screws with Kroil for a couple days before attempting to remove them, and use JIS standard, NOT Phillips, screwdriver bits, and this will greatly improve the odds that you will not break or strip a carb holder fastener as so many have done. Let me know if you need info on JIS bits, I have a good link for making your own at no cost. Ed

Spraying junk on the boots only finds large leaks. Smaller leaks don't show up.

I'd just replace the boots. They are cheap enough and it's time if you are using the originals.

Problem solved!!!
They are new boots, I didn't think vacuum leak... sprayed some carb fluid at idle and she bogged way down!!! When taking the boots off I did notice the inner two were not very tight, inspected the boots and could not see or feel any damage, put the boots back on, nice and tight this time, she now has normal throttle response and just got the sync done! Now all she needs is some new tires and I can start fine tuning!
As always, you gentlemen are an unparalleled resource! Thank yall!