1992 115 hp V4 2 stroke had carbs done last year ran great all summer but this spring (as the fish are in the river) it will not Idle. It will run great at high RPM's

have the throttle properly adjusted at the carbys and have the advance for the timing checked

Thermostat faulty or blockage in block not allowing water to flow thru block.remove cylinder head and side water jacket

I Sujest You Clean The Carbs Again ,Standing For One Year Often
Leaves The Carbs Dry And Full Of Deposits
Cheers
Gordon

Ignition module is failing

The "L" drive was a total pain. It threw exhaust boots on a regular basis. To get it to adjust for idle, you need to put it in the water and run it up to 1500 rpm in gear and get it to smooth out using the idle mixture adjustments. It would almost always be to lean when it ran right, so for idle you would need to run the "jackrabbit" starts until you have adjusted it to do that smoothy. Then your done. If it will not then do all those thing smoothly (idle, run, jackrabbit start) you will need to take the emulsion tubs out of the carbs and clean them.

When they are set properly, you can shine your timing light down the throat of each carb and the spray pattern inside the carb should be identical.

sure its not running on autochoke ,sounds like it to but if you have done a nice job on the engine then you may need to adjust the mixture on idle which for the inspection must be less than 2% it will idle well if this higher as its burning more fuel on idle but this is not allowed for the test ,once it leaves the test station ? This has one of them fish type carbs and havent done one for many a year but the mixture idle is on the base of the carb and they normally have a spring on the screw shank to hold them

this sounds like the high idle circuit of carberetor has debri in the needle. I would consider cleaning carb and try again. If still continues then this would make me look at fuel pump. These 2 things are where you need to start.

Possibly yes; also may be a coil issue too. I had seen this same issue some time back with an older KZ650, in the end it was a coil. By stroke of luck working with the carbs put the wires back as required.
I hope this may have helped,
Tom

While at the river try to adjust the fuel air mixture. When you are on the water it puts the engine under a load and if that dont work then dont be afraid to bump up the idle stop screw slightly.

Reving in neutral does not mean the same thing as under load. If you need to pull 4500rpm under load and for an instant the load was gone, you would probably overrev to 6500. With the cover off and motor not running move the throttle to full forward. Look at your carbs and see if the throttle plates are wide open. If they are not all wide open take it back to the dealer. The throttle adjustment is off. You need the full range of travel from idle to topend.