Accepted Answer

Is it turning 1640 in the water or out of the water? The idle will drop when the pump is submerged and moving the boat forward.
Spark plug gap does not usually affect idle speed, unless it is so far off it causes it to not idle. High idle speed is not a symptom of a spark plug gap related problem. Those usually are indicated by drivability or running problems.

There is an idle screw that pushes on a tab off the pulley for the throttle cable. Here is a link to a parts blow up of your carbs. The idle screw is #31.

http://www.babbittsonline.com/pages/parts/viewbybrand/14/Polaris.aspx
Then go to SELECT, and pick PWC out of the drop down box,
Then click on the drop down box and scroll down the list until you get to the 2000 Genesis. Then once the parts diagrams load, find the page in the parts fieche that shows the carbs. and look for #31, It is above the pivot for the pulley, and towards the engine. Turning that screw in increases RPM and turning it out Reduced RPM.
I wish you well!
RSRBOB

If you can not get a good look at the pulley that the throttle cable attaches to, you might be able to use a mirror to look at the pulley. To help you locate which is the throttle cable, and what it is pulling on, either you pull the throttle trigger repeatedly or have someone pumping the throttle trigger for you so you can see the pulley it is moving. Then just look for the knob to adjust the idle. Screwing it in will increase idle speed, backing it off will slow the engine idle down.
Thanks
RSRBOB

Edited by RSRBOB on 7/9/2009 at 3:13 AM

Expert:	RSRBOB
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Answered:	7/9/2009

Technician

Former Yamaha Factory Service Rep, Dlr Line Tech, Serv Mgr, G/M