"Advancer" on Mikuni's

I was reading about cleaning and lubing the "advancer" in an old thread. After searching the hell out of this I can't find anything anywhere that describes how to do this... like mainly, where is the advancer and what exactly does it do? I've had some ongoing idle problems with my KZ900 and this is about the only thing I haven't tried. The thing is, it's very hard to adjust the idle below 1800 or 2000. I'll warm the bike up, then set the idle using the adjusting knob, to like 1200, then next time I come to a stop light the idle will be way too low, like under 900. So I'll turn the knob and bring it back up to 1200 and next stoplight it'll be up above 2000. After extensive trial and error I can get it to idle around 1500 and stay there for the most part, but a quick snap of the throttle often will bring it below 1000 again. I've gone through checking the return spring, cable routing (turning handlebars doesn't change idle) air leaks, replaced intake boots... Anyway, thought it wouldn't hurt to clean and lube the advancer if I can figure out where it is.

Think points plate.


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Have you checked fuel level and vacuum synced the carbs?

And yes, the advancer is the mechanical advance mechanism under the points plate. You need to break down the assembly and grease everything so it rotates smoothly.

There's a Z1 pdf manual floating around the internet & the KZ900 advancer is probably the same.
Get an engine cover gasket beforehand. I usually keep several on hand. see diagrams at Partzilla.
Separate the rotor from the advancer body for cleaning. Check that the springs aren't stretched or damaged or anything.
Lubricate the advancer & fill the groove w grease. After assembly, operate the rotor by hand to check that it snaps back.
I used a high temp lubricant the last time. white lithium grease & dielectric grease are too thin.

This is the advancer. It sits under the points breaker plate... real easy To lubricate. Not meant for number identifying just as a sample photo...

Nessism wrote: Have you checked fuel level and vacuum synced the carbs?

And yes, the advancer is the mechanical advance mechanism under the points plate. You need to break down the assembly and grease everything so it rotates smoothly.

I bench synced the carbs but didn't put the gages on them. I'll check out the timing advance. Ive done everything else I can think of. Thing is, with a bunch of messing I can get it stable at 1500 for the most part. Does anyone think that's too high? I think the manual call for 1200 to 1500

Idle for the Kz900 should be 800 to 1000. Timing advance starts about 1350, with full advance around 2300.

If and when you get the advancer off your motor to clean and lube it, make sure the small rubber dampers are in place on the arms and that they aren't deteriorated. Also check the advancer springs for good condition while you are in there. Junk likes to collect under the rubber pads so give them a good cleaning and make sure they don't stick to the shaft. Sticking advancer arms can cause absolute fits to how an engine runs. The arms must move freely and smoothly. Should you by chance decide to replace your advancer plate with a new one make sure to clean all the old grease off the new one before installing it.
Rick H.

Do your carbs have a accelerator pump ???
On my bike ( Turbo Kit ) I have one 42 mm Mikuni flat slide and it has a adjustable accelerator pump which can be made to advance at different throttle settings.when it starts working.
Just a thought . Dont know what your 4 carbs have built into them
Dave