Carb tuning on jet ski...please help!!?

Question

I have an older stand up ski and I'm having some issues tuning it. If I can get it running over roughly 2500 rpms (best guess as there is no rpms gauge), it will run flawlessly until I stop it. However, when I'm idling and give half or more throttle it just dies every time. I have to tap the throttle carefully and get the engine spinning before I can actually take off.

I initially thought the engine was running rich and leaned out the low s***w until it was only half a turn out. I didn't want to close it more than that so I increased the pop off pressure and basically have the same problem. When I changed the pop off pressure I set the low s***w at 2 turns out and the low end response barely changed between 2 turns out all the way to 3/4 turns out.

Is my initial assumption wrong? I'm kind of at a loss here as everything I try doesn't seem to work or change anything. Clearly it's a tuning problem but I can't figure out which way to go.

Answer 1

Ok, before you go any further we need to know what you got? What model, year and it it is a Kawasaki or Yamaha?

Answer 2

An engine that is too lean will loose power under load.  Try to make the fuel richer.  Your engine is under the most load when you are taking off.  Make it richer and your power may come back.

Answer 3

have the carbs. been cleaned and kitted?  do you have good compression?  does it have a rotary valve?  it doesn't take much wear there to cause problems.