Throttle response issues "87 Suzuki DT-65

[Trackbolt]

We recently acquired a 1987 Suzuki 65 hp two stroke outboard. Compression an even 130 in one, two and three. Installed new water pump kit and resealed lower unit. All three plugs brown but a little oily. After come checks we started it in a tank and it ran well at idle. Once on the boat out on the water things are not as they should be. The motor will bog when you advance the throttle. Sometimes the throttle responds as it should then loses rpms and bogs. Other times it bogs as soon as the throttle advances but with a little feathering it will open up and the boat will hop right up on plane and run as it should. It seems the motor struggles once a significant load is placed it such as getting a skier up on plane. And there were the times (few) it ran like a scalded dog. So far we have done the following.

Disassembled all three carbs soaked in cleaner blown out all passages and jets with compressed air and install new kits in each one.
Using OEM manual set all carb linkages according to specs.
Replaced fuel fileter.
Rebuilt fuel pump.
Installed new fuel lines and connectors from the tank to the motor.
Installed three new spark plugs.
Checked throttle advance switch for continuity according to the Suzuki OEM Manual.

The engine runs smooth in all ranges with no misses and it will respond to the trolling speed switch. When it bogs under throttle it seems as it is starving for fuel. The three new spark plugs are showing that all three cylinders are firing evenly and the fuel reaching each plug is the same for all three. Compression continues to be an even 130 psi in each cylinder with a warm motor. I do not have the OEM test equipment that is outlined in the Suzuki manual. I've got a timing light, multimeter and just enough knowledge to know how to use them, I am an old points and condenser magneto guy from another time. I can see mechanical carb/ignition timing sync. and can follow movement of linkages. I have a lot to learn with the Suzuki's Electronic IC Ignition. Any help would be greatly appreciated.

Thanks
Tony

 

[99yam40]

is timing advancing to spec when problem shows up?
light should also show if a plug is loosing spark by moving it to the different plug wires.

If good spark to all plugs and timing is advancing properly then you are left with fuel problems

Too much or too little will not let a cylinder fire properly

 

[Trackbolt]

Thanks for the response. Here is where we are now. Spark at the plugs is hot at all speeds. We checked the throttle advance/idle switch and at the idle position it shows continuity according to specs. With a timing light check the timing advances at start and then sets back after 15 seconds. The timing responds to the trolling switch. In the tank with the motor in forward the timing advanced with the throttle to about 20 degrees. that was about as much rev as we dared do in the small tank. No sign of bogging but as I said it the problem is intermittent. The fuel system is clean with no signs of gum, varnish, dirt or corrosion, We did remove the throttle/idle switch and advanced the switch with a screw driver. With the ohm meter on the throttle wire the switch showed no continuity below 15 degrees which the manual says is spec. Above 15 degrees the throttle switch showed continuity with a steady whistle and in the mid range the ohm meter began to chirp then as I advanced the switch to wide open throttle the meter whistled steadily. The motor has always started and idled as it should. The bog problem when it happened happened at the low-mid range throttle position. I don't know but I am beginning to suspect the throttle /idle switch.