idle kz900 kerker

hello,

after a fresh engine rebuid my idle is eratic.
Look like a air leaking but i recheck all but intake manifolds and exhaust are good. No drop if i use "starter fuid " on the carbs...

the bike was working perfectly with a 4in1 kerker comp large baffle, pods , z1 vm28sc at 17.5 - 117.5 .

The bike was working perfectly with a 4in2 exhaust, air box with single k&n air filter, kz900 vm26 at stock 17.5 115 .

So actually i have the stock kz900, 4in1 kerker large baffle, stock ait box with k&n air filter.

i can't have 1000 rpm. The tacho needle go to 1300 after 1 min and if i try to reduce the idle screw to 1000 the engine drop to 500 and die.

Can its be my carb set up? must i go lean or rich ? i'm surpise to go richer because those carb are rich from factury ...


 

Have you vacuum synced the carbs?

I just did it. It don't resolve the problem.

How old are the intake manifolds? 

Good and sealed. That's was my first search.

Some spray with break cleaner around the intake manifolds tell you the truth....

Spraying junk on the boots is NOT a definitive test.  I'd replace the boots if they are original.  

Have you rebuilt the choke plungers?  If not, you may have a fuel leak through the choke circuit.

Clogged pilot circuits can cause those symptoms. Screwing in the idle adjuster far enough will allow the main jet to start flowing, making up for the clogged pilots, but raising the idle too high. Unscrewing the idle adjuster will finally close the butterflies enough that the mains can no longer flow, causing the carbs to try and run on the clogged pilots, resulting in a really low idle speed.

Maybe I’m missing something. What carbs are you using that give you high idle. You state the bike was running good with Z1-28SC & Kz-26SS. If that’s the case can you put one of those racks back on to rule out some rebuild fault.